Earth and Planetary Sciences › Atmospheric Science

Atmospheric Ozone and Climate

Works Count: 92374

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Description

This cluster of papers focuses on the study of stratospheric chemistry, with a particular emphasis on the impacts of ozone depletion, changes in stratospheric water vapor, and the influence of the Brewer-Dobson circulation on climate. It also covers the role of remote sensing instruments and chemical transport models in understanding atmospheric composition and climate impact. The cluster highlights the significance of the Montreal Protocol in protecting the ozone layer and addresses the influence of solar cycle variations on stratospheric chemistry.

Keywords

Stratospheric Water Vapor; Ozone Depletion; Tropopause Layer; Climate Impact; Brewer-Dobson Circulation; Atmospheric Composition; Remote Sensing Instruments; Chemical Transport Model; Solar Cycle Influence; Montreal Protocol

On the depletion of Antarctic ozone

1986-06-01

Susan Solomon , Rolando R. García , F. S. Rowland +1 more

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Tropospheric ozone: Seasonal behavior, trends, and anthropogenic influence

1985-10-20

Jennifer A. Logan

We present an analysis of data for tropospheric ozone with a focus on spatial and temporal variations. Surface ozone at mid‐latitudes displays two modes of seasonal behavior: a broad summer … We present an analysis of data for tropospheric ozone with a focus on spatial and temporal variations. Surface ozone at mid‐latitudes displays two modes of seasonal behavior: a broad summer maximum within a few hundred kilometers of populated and industrialized regions in Europe and the United States and a minimum in summer or autumn in sparsely populated regions remote from industrial activity‐in Tasmania and Canada for example. The current data base for different regions, in combination with limited historical data, indicates that summertime concentrations of ozone near the surface in rural areas of Europe and the central and eastern United States may have increased by approximately 6–22 ppb (20%–100%) since the 1940's. The seasonal cycle of ozone in the middle troposphere over Europe, the United States, and northern Japan is very similar to that at the surface with a summer maximum, but it is quite different from that at 300 mbar, which is characterized by a maximum in spring. There is good evidence for an increase in ozone in the middle troposphere over Europe during the past 15 years and weaker evidence for a similar increase over North America and Japan. The increase in tropospheric ozone contributes significantly to the trend in the column of ozone and may compensate for 20%–30% of the decrease in ozone in the stratosphere over middle and high latitudes of the northern hemisphere. We argue that the summer maximum in ozone and the observed trends are due to photochemical production associated with anthropogenic emissions of NO x , hydrocarbons, and CO from combustion of fossil fuels. A strong seasonal variation in ozone observed at Natal, Brazil (6°S), may also result from emissions of NO x and hydrocarbons, in this case from agricultural burning. Maximum concentrations at Natal are similar to values found at mid‐latitudes in summer. Tropical ozone exhibits strong spatial and temporal variability.

A Dynamical Model of the Stratospheric Sudden Warming

1971-11-01

Taroh Matsuno

The dynamics of the stratosphere sudden warming phenomenon is discussed in terms of the interaction of vertically propagating planetary waves with zonal winds. If global-scale disturbances are generated in the … The dynamics of the stratosphere sudden warming phenomenon is discussed in terms of the interaction of vertically propagating planetary waves with zonal winds. If global-scale disturbances are generated in the troposphere, they propagate upward into the stratosphere, where the waves act to decelerate the polar night jet through the induction of a meridional circulation. Thus, the distortion and the break-down of the polar vortex occur. If the disturbance is intense and persists, the westerly jet may eventually disappear and an easterly wind may replace it. Then “critical layer interaction” takes place. Further intensification of the easterly wind and rapid warming of the polar air are expected to occur as well as weakening of the disturbance. The model is verified by numerical integrations of the adiabatic-geostrophic potential vorticity equation. Computed results possess features similar to those observed in sudden warming phenomena.

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The influence of nitrogen oxides on the atmospheric ozone content

1970-04-01

Paul J. Crutzen

Abstract The probable importance of NO and NO 2 in controlling the ozone concentrations and production rates in the stratosphere is pointed out. Observations on and determinations of nitric acid … Abstract The probable importance of NO and NO 2 in controlling the ozone concentrations and production rates in the stratosphere is pointed out. Observations on and determinations of nitric acid concentrations in the stratosphere by Murcray, Kyle, Murcray and Williams (1968) and Rhine, Tubbs and Dudley Williams (1969) support the high NO and NO 2 concentrations indicated by Bates and Hays (1967). Some processes which may lead to production of nitric acid are discussed. The importance of O ( 1 S), possibly produced in the ozone photolysis below 2340 Å, on the ozone photochemistry is mentioned.

SCIAMACHY: Mission Objectives and Measurement Modes

1999-01-01

H. Bovensmann , John P. Burrows , Michael Buchwitz +5 more

SCIAMACHY (Scanning Imaging Absorption Spectrometer for Atmospheric Chartography) is a spectrometer designed to measure sunlight transmitted, reflected, and scattered by the earth’s atmosphere or surface in the ultraviolet, visible, and … SCIAMACHY (Scanning Imaging Absorption Spectrometer for Atmospheric Chartography) is a spectrometer designed to measure sunlight transmitted, reflected, and scattered by the earth’s atmosphere or surface in the ultraviolet, visible, and near-infrared wavelength region (240–2380 nm) at moderate spectral resolution (0.2–1.5 nm, λ/Δλ ≈ 1000–10 000). SCIAMACHY will measure the earthshine radiance in limb and nadir viewing geometries and solar or lunar light transmitted through the atmosphere observed in occultation. The extraterrestrial solar irradiance and lunar radiance will be determined from observations of the sun and the moon above the atmosphere. The absorption, reflection, and scattering behavior of the atmosphere and the earth’s surface is determined from comparison of earthshine radiance and solar irradiance. Inversion of the ratio of earthshine radiance and solar irradiance yields information about the amounts and distribution of important atmospheric constituents and the spectral reflectance (or albedo) of the earth’s surface. SCIAMACHY was conceived to improve our knowledge and understanding of a variety of issues of importance for the chemistry and physics of the earth’s atmosphere (troposphere, stratosphere, and mesosphere) and potential changes resulting from either increasing anthropogenic activity or the variability of natural phenomena. Topics of relevance for SCIAMACHY are tropospheric pollution arising from industrial activity and biomass burning, troposphere–stratosphere exchange processes, stratospheric ozone chemistry focusing on the understanding of the ozone depletion in polar regions as well as in midlatitudes, and solar variability and special events such as volcanic eruptions, and related regional and global phenomena. Inversion of the SCIAMACHY measurements enables the amounts and distribution of the atmospheric constituents O3, O2, O2(1Δ), O4, BrO, OClO, ClO, SO2, H2CO, NO, NO2, NO3, CO, CO2, CH4, H2O, N2O, and aerosol, as well as knowledge about the parameters pressure p, temperature T, radiation field, cloud cover, cloud-top height, and surface spectral reflectance to be determined. A special feature of SCIAMACHY is the combined limb–nadir measurement mode. The inversion of the combination of limb and nadir measurements will enable tropospheric column amounts of O3, NO2, BrO, CO, CH4, H2O, N2O, SO2, and H2CO to be determined.

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Ozone destruction and photochemical reactions at polar sunrise in the lower Arctic atmosphere

1988-07-01

Leonard A. Barrie , J. W. Bottenheim , R. C. Schnell +2 more

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Evidence for a world circulation provided by the measurements of helium and water vapour distribution in the stratosphere

1949-10-01

A. W. Brewer

Abstract Information is now available regarding the vertical distribution of water vapour and helium in the lower stratosphere over southern England. The helium content of the air is found to … Abstract Information is now available regarding the vertical distribution of water vapour and helium in the lower stratosphere over southern England. The helium content of the air is found to be remarkably constant up to 20 km but the water content is found to fall very rapidly just above the tropopause, and in the lowest 1 km of the stratosphere the humidity mixing ratio falls through a ratio of 10—1. The helium distribution is not compatible with the view of a quiescent stratosphere free from turbulence or vertical motions. The water‐vapour distribution is incompatible with a turbulent stratosphere unless some dynamic process maintains the dryness of the stratosphere. In view of the large wind shear which is normally found just above the tropopause it is unlikely that this region is free from turbulence. The observed distributions can be explained by the existence of a circulation in which air enters the stratosphere at the equator, where it is dried by condensation, travels in the stratosphere to temperate and polar regions, and sinks into the troposphere. The sinking, however, will warm the air unless it is being cooled by radiation and the idea of a stratosphere in radiative equilibrium must be abandoned. The cooling rate must lie between about 0.1 and 1.1°C per day but a value near 0.5°C per day seems most probable. At the equator the ascending air must be subject to heating by radiation. The circulation is quite reasonable on energy considerations. It is consistent with the existence of lower temperatures in the equatorial stratosphere than in polar and temperate regions, and if the flow can carry ozone from the equator to the poles then it gives a reasonable explanation of the high ozone values observed at high latitudes. The dynamic consequences of the circulation are not considered. It should however be noted that there is considerable difficulty to account for the smallness of the westerly winds in the stratosphere, as the rotation of the earth should convert the slow poleward movement into strong westerly winds.

Stratosphere‐troposphere exchange

1995-11-01

James R. Holton , Peter Haynes , M. E. McIntyre +3 more

In the past, studies of stratosphere‐troposphere exchange of mass and chemical species have mainly emphasized the synoptic‐ and small‐scale mechanisms of exchange. This review, however, includes also the global‐scale aspects … In the past, studies of stratosphere‐troposphere exchange of mass and chemical species have mainly emphasized the synoptic‐ and small‐scale mechanisms of exchange. This review, however, includes also the global‐scale aspects of exchange, such as the transport across an isentropic surface (potential temperature about 380 K) that in the tropics lies just above the tropopause, near the 100‐hPa pressure level. Such a surface divides the stratosphere into an “overworld” and an extratropical “lowermost stratosphere” that for transport purposes need to be sharply distinguished. This approach places stratosphere‐troposphere exchange in the framework of the general circulation and helps to clarify the roles of the different mechanisms involved and the interplay between large and small scales. The role of waves and eddies in the extratropical overworld is emphasized. There, wave‐induced forces drive a kind of global‐scale extratropical “fluid‐dynamical suction pump,” which withdraws air upward and poleward from the tropical lower stratosphere and pushes it poleward and downward into the extratropical troposphere. The resulting global‐scale circulation drives the stratosphere away from radiative equilibrium conditions. Wave‐induced forces may be considered to exert a nonlocal control, mainly downward in the extratropics but reaching laterally into the tropics, over the transport of mass across lower stratospheric isentropic surfaces. This mass transport is for many purposes a useful measure of global‐scale stratosphere‐troposphere exchange, especially on seasonal or longer timescales. Because the strongest wave‐induced forces occur in the northern hemisphere winter season, the exchange rate is also a maximum at that season. The global exchange rate is not determined by details of near‐tropopause phenomena such as penetrative cumulus convection or small‐scale mixing associated with upper level fronts and cyclones. These smaller‐scale processes must be considered, however, in order to understand the finer details of exchange. Moist convection appears to play an important role in the tropics in accounting for the extreme dehydration of air entering the stratosphere. Stratospheric air finds its way back into the troposphere through a vast variety of irreversible eddy exchange phenomena, including tropopause folding and the formation of so‐called tropical upper tropospheric troughs and consequent irreversible exchange. General circulation models are able to simulate the mean global‐scale mass exchange and its seasonal cycle but are not able to properly resolve the tropical dehydration process. Two‐dimensional (height‐latitude) models commonly used for assessment of human impact on the ozone layer include representation of stratosphere‐troposphere exchange that is adequate to allow reasonable simulation of photochemical processes occurring in the overworld. However, for assessing changes in the lowermost stratosphere, the strong longitudinal asymmetries in stratosphere‐troposphere exchange render current two‐dimensional models inadequate. Either current transport parameterizations must be improved, or else, more likely, such changes can be adequately assessed only by three‐dimensional models.

The determination of an accurate isotope dependent potential energy surface for water from extensive ab initio calculations and experimental data

1997-03-15

Harry Partridge , David W. Schwenke

We report on the determination of a high quality ab initio potential energy surface (PES) and dipole moment function for water. This PES is empirically adjusted to improve the agreement … We report on the determination of a high quality ab initio potential energy surface (PES) and dipole moment function for water. This PES is empirically adjusted to improve the agreement between the computed line positions and those from the HITRAN 92 data base with J⩽5 for H216O. The changes in the PES are small, nonetheless including an estimate of core (oxygen 1s) electron correlation greatly improves the agreement with the experiment. Using this adjusted PES, we can match 30 092 of the 30 117 transitions in the HITRAN 96 data base for H216O with theoretical lines. The 10, 25, 50, 75, and 90 percentiles of the difference between the calculated and tabulated line positions are −0.11, −0.04, −0.01, 0.02, and 0.07 cm−1. Nonadiabatic effects are not explicitly included. About 3% of the tabulated line positions appear to be incorrect. Similar agreement using this adjusted PES is obtained for the 17O and 18O isotopes. For HD16O, the agreement is not as good, with a root-mean-square error of 0.25 cm−1 for lines with J⩽5. This error is reduced to 0.02 cm−1 by including a small asymmetric correction to the PES, which is parameterized by simultaneously fitting to HD16O and D216O data. Scaling this correction by mass factors yields good results for T2O and HTO. The intensities summed over vibrational bands are usually in good agreement between the calculations and the tabulated results, but individual line strengths can differ greatly. A high-temperature list consisting of 307 721 352 lines is generated for H216O using our PES and dipole moment function.

Global distribution of UV‐absorbing aerosols from Nimbus 7/TOMS data

1997-07-01

J. R. Herman , P. K. Bhartia , Omar Torres +3 more

Global distributions of UV‐absorbing aerosols are obtained using measured differences between the 340 and the 380 nm radiances from the Nimbus 7 Total Ozone Mapping Spectrometer (TOMS) for the years … Global distributions of UV‐absorbing aerosols are obtained using measured differences between the 340 and the 380 nm radiances from the Nimbus 7 Total Ozone Mapping Spectrometer (TOMS) for the years 1979–1993. Time series are shown for major sources of biomass burning and desert dust giving the frequency of occurrence and areal coverage over land and oceans. Minor sources of UV‐absorbing aerosols in the atmosphere are also discussed (volcanic ash and oil fires). Relative values of year‐to‐year variability of UV‐absorbing aerosol amounts are shown for major aerosol source regions: (1) central South America (Brazil) near 10°S latitude; (2) Africa near 0°–20°S and 0° to 10°N latitude; (3) Saharan Desert and sub‐Saharan region (Sahel), Arabian Peninsula, and the northern border region of India; (4) agricultural burning in Indonesia, Eastern China, and Indochina, and near the mouth of the Amazon River; and (5) coal burning and dust in northeastern China. The first three of these regions dominate the injection of UV‐absorbing aerosols into the atmosphere each year and cover areas far outside of their source regions from advection of UV‐absorbing particulates by atmospheric wind systems. During the peak months, smoke and dust from these sources are transported at altitudes above 1 km with an optical depth of at least 0.1 and can cover about 10% of the Earth's surface. Boundary layer absorbing aerosols are not readily seen by TOMS because the small amount of underlying Rayleigh scattering leads to a small signal. Significant portions of the observed dust originate from agricultural regions frequently within arid areas, such as in the Sahel region of Africa, especially from the dry lake‐bed near Lake Chad (13.5°N, 14°E), and intermittently dry drainage areas and streams. In addition to drought cycle effects, this suggests there may be an anthropogenic component to the amount of dust injected into the atmosphere each year. Detection of absorbing aerosols and calculation of optical depths are affected by the presence of large‐scale and subpixel clouds in the TOMS field of view.

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A Parameterization for the Absorption of Solar Radiation in the Earth's Atmosphere

1974-01-01

Andrew A. Lacis , James E. Hansen

A method is described for rapidly computing the amount of solar energy absorbed at the earth's surface and in the atmosphere as a function of altitude. The method is a … A method is described for rapidly computing the amount of solar energy absorbed at the earth's surface and in the atmosphere as a function of altitude. The method is a parametric treatment, but the form of the solution and the coefficients involved are based on accurate multiple-scattering computations. In this treatment the absorption varies with the amount and type of clouds, the humidity, the zenith angle of the sun, and the albedo of the earth's surface. Within the stratosphere the absorption also depends on the vertical distribution of ozone. This parameterization for solar radiation is being used in current versions of the global atmospheric circulation model developed at the Goddard Institute for Space Studies.

A survey of interstellar H I from L-alpha absorption measurements. II

1978-08-01

R. C. Bohlin , Blair D. Savage , J. F. Drake

view Abstract Citations (3019) References (37) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS A survey of interstellar H I from Lalpha absorption measurements. II. Bohlin, R. C. … view Abstract Citations (3019) References (37) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS A survey of interstellar H I from Lalpha absorption measurements. II. Bohlin, R. C. ; Savage, B. D. ; Drake, J. F. Abstract This paper presents interstellar H I column densities, mean H I space densities, total neutral hydrogen column densities, and total mean hydrogen space densities toward 100 stars surveyed in the L-alpha region with the U2 detector of the Copernicus satellite. The data for 47 stars are compared with OAO 2 results, and ratios of gas to E(B-V) color excess are computed for 30 'intercloud' stars, 45 'cloud' stars, and the combined sample of 75 stars. A definitive value of 5.8 x 10 to the 21st power atoms/sq cm per mag is obtained for the mean ratio of total neutral hydrogen to color excess, indicating that this ratio seems to be a constant, independent of location in the sky, except possibly toward stars with anomalous extinction. The anomalous ratio determined for Rho Oph is examined, and the galactic distribution of neutral hydrogen is evaluated. The following values are estimated for matter in the galactic plane within 500 pc of the sun: a total mean hydrogen space density of 1.15 atoms/cu cm, a mean H2 space density of 0.143 molecule/cu cm (possibly a lower limit), and a mean H I space density of 0.86 atom/cu cm (a possible overestimate). Publication: The Astrophysical Journal Pub Date: August 1978 DOI: 10.1086/156357 Bibcode: 1978ApJ...224..132B Keywords: Hydrogen Clouds; Interstellar Gas; Lyman Alpha Radiation; Molecular Absorption; Ultraviolet Spectra; Abundance; Hydrogen Atoms; Interstellar Extinction; Neutral Particles; Oao 2; Satellite Observation; Astrophysics; Interstellar Matter:Molecules; Interstellar Matter:Neutral Hydrogen full text sources ADS | data products SIMBAD (101)

Model atmospheres for G, F, A, B, and O stars

1979-05-01

R. L. Kurucz

view Abstract Citations (3777) References (38) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Model atmospheres for G, F, A, B, and O stars. Kurucz, R. L. Abstract … view Abstract Citations (3777) References (38) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Model atmospheres for G, F, A, B, and O stars. Kurucz, R. L. Abstract A grid of LTE model atmospheres is presented for effective temperatures ranging from 5500 to 50,000 K, gravities from the main sequence down to the radiation-pressure limit, and abundances solar, 1/10 solar, and 1/100 solar. The models were computed by use of a statistical distribution-function representation of the opacity of almost a million atomic lines. For each model the temperature structure, fluxes, UBV and uvby colors, bolometric correction, and Balmer line profiles are tabulated. The solar-abundance models are compared with narrow-, intermediate-, and wide-band photometry and found to be in good agreement with the observations for effective temperatures above 8000 K. Excellent agreement exists with the spectrophotometry and Balmer line profiles of Vega. A small systematic error in the colors of late A and F stars is probably due to an overstimate of convection in weakly convective models. This error does not seem to affect greatly the use of the predicted colors for differential studies. The solar model has approximately a 2% error in the V flux because molecular lines were not included. Publication: The Astrophysical Journal Supplement Series Pub Date: May 1979 DOI: 10.1086/190589 Bibcode: 1979ApJS...40....1K Keywords: Atmospheric Models; Early Stars; F Stars; G Stars; Line Spectra; Stellar Atmospheres; Stellar Models; A Stars; Abundance; B Stars; Balmer Series; Distribution Functions; Error Analysis; O Stars; Opacity; Radiation Pressure; Solar Atmosphere; Solar Simulation; Spectrophotometry; Statistical Analysis; Tables (Data); Temperature Effects; Astrophysics; A Stars:Atmospheres; Atmospheres:B Stars; Atmospheres:F Stars; Atmospheres:G Stars; Atmospheres:O Stars; Early-Type Stars:Spectrophotometry; Stellar Atmospheres:Models full text sources ADS | data products CDS (2) SIMBAD (1) Related Materials (1) Catalog: 1993yCat.6039....0K

The quasi‐biennial oscillation

2001-05-01

Mark Baldwin , Lesley J. Gray , Timothy J. Dunkerton +7 more

The quasi‐biennial oscillation (QBO) dominates the variability of the equatorial stratosphere (∼16–50 km) and is easily seen as downward propagating easterly and westerly wind regimes, with a variable period averaging … The quasi‐biennial oscillation (QBO) dominates the variability of the equatorial stratosphere (∼16–50 km) and is easily seen as downward propagating easterly and westerly wind regimes, with a variable period averaging approximately 28 months. From a fluid dynamical perspective, the QBO is a fascinating example of a coherent, oscillating mean flow that is driven by propagating waves with periods unrelated to that of the resulting oscillation. Although the QBO is a tropical phenomenon, it affects the stratospheric flow from pole to pole by modulating the effects of extratropical waves. Indeed, study of the QBO is inseparable from the study of atmospheric wave motions that drive it and are modulated by it. The QBO affects variability in the mesosphere near 85 km by selectively filtering waves that propagate upward through the equatorial stratosphere, and may also affect the strength of Atlantic hurricanes. The effects of the QBO are not confined to atmospheric dynamics. Chemical constituents, such as ozone, water vapor, and methane, are affected by circulation changes induced by the QBO. There are also substantial QBO signals in many of the shorter‐lived chemical constituents. Through modulation of extratropical wave propagation, the QBO has an effect on the breakdown of the wintertime stratospheric polar vortices and the severity of high‐latitude ozone depletion. The polar vortex in the stratosphere affects surface weather patterns, providing a mechanism for the QBO to have an effect at the Earth's surface. As more data sources (e.g., wind and temperature measurements from both ground‐based systems and satellites) become available, the effects of the QBO can be more precisely assessed. This review covers the current state of knowledge of the tropical QBO, its extratropical dynamical effects, chemical constituent transport, and effects of the QBO in the troposphere (∼0–16 km) and mesosphere (∼50–100 km). It is intended to provide a broad overview of the QBO and its effects to researchers outside the field, as well as a source of information and references for specialists. The history of research on the QBO is discussed only briefly, and the reader is referred to several historical review papers. The basic theory of the QBO is summarized, and tutorial references are provided.

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TROPOMI on the ESA Sentinel-5 Precursor: A GMES mission for global observations of the atmospheric composition for climate, air quality and ozone layer applications

2012-02-20

Pepijn Veefkind , Ilse Aben , Kevin McMullan +7 more

Photoelectric heating of interstellar gas

1978-04-01

B. T. Draine

view Abstract Citations (1244) References (78) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Photoelectric heating of interstellar gas. Draine, B. T. Abstract Photoelectric emission from interstellar grains … view Abstract Citations (1244) References (78) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Photoelectric heating of interstellar gas. Draine, B. T. Abstract Photoelectric emission from interstellar grains and its consequences for the heating and cooling of interstellar gas are reexamined. The physics of photoemission is briefly reviewed, the photoemissive properties of interstellar grains are examined, and the absorption efficiency and total geometric cross section of the grains are estimated. Some aspects of gas-grain interactions are considered, the interstellar UV energy density is discussed, and the grain potential and heating rate are evaluated for the interstellar UV background as well as for a wide range of electron densities and temperatures. Steady-state solutions for the gas are obtained, and their relevance to the interstellar medium is briefly assessed. The time-dependent cooling of a fossil H II region is analyzed, and it is suggested that fossil H II in the wakes of runaway O stars can produce significant amounts of intermediate-temperature (about 500 to 3000 K) H I. It is concluded that: (1) interstellar grains are likely to have effective photoelectric thresholds of approximately 8 eV and (2) photoemission from grains is a major contributor to the heating of the cool phase of the interstellar medium. Publication: The Astrophysical Journal Supplement Series Pub Date: April 1978 DOI: 10.1086/190513 Bibcode: 1978ApJS...36..595D Keywords: Gas Heating; Interstellar Gas; Photoelectric Emission; Radiant Cooling; Cations; Gas Ionization; Gas Temperature; H Ii Regions; Scaling Laws; Spiral Galaxies; Steady State; Time Dependence; Ultraviolet Radiation; Astrophysics; Grains:Interstellar Matter; Interstellar Gas: Heating full text sources ADS |

Light scattering in planetary atmospheres

1974-10-01

James E. Hansen , Larry D. Travis

THE HITRAN MOLECULAR SPECTROSCOPIC DATABASE AND HAWKS (HITRAN ATMOSPHERIC WORKSTATION): 1996 EDITION

1998-11-01

Laurence S. Rothman , C. P. Rinsland , Alan S. Goldman +7 more

Annular Modes in the Extratropical Circulation. Part II: Trends

2000-03-01

David W. J. Thompson , John M. Wallace , Gabriele C. Hegerl

The authors exploit the remarkable similarity between recent climate trends and the structure of the “annular modes” in the month-to-month variability (as described in a companion paper) to partition the … The authors exploit the remarkable similarity between recent climate trends and the structure of the “annular modes” in the month-to-month variability (as described in a companion paper) to partition the trends into components linearly congruent with and linearly independent of the annular modes. The index of the Northern Hemisphere (NH) annular mode, referred to as the Arctic Oscillation (AO), has exhibited a trend toward the high index polarity over the past few decades. The largest and most significant trends are observed during the “active season” for stratospheric planetary wave–mean flow interaction, January–March (JFM), when fluctuations in the AO amplify with height into the lower stratosphere. For the periods of record considered, virtually all of the JFM geopotential height falls over the polar cap region and the strengthening of the subpolar westerlies from the surface to the lower stratosphere, ∼50% of the JFM warming over the Eurasian continent, ∼30% of the JFM warming over the NH as a whole, ∼40% of the JFM stratospheric cooling over the polar cap region, and ∼40% of the March total column ozone losses poleward of 40°N are linearly congruent with month-to-month variations in the AO index. Summertime sea level pressure falls over the Arctic basin are suggestive of a year-round drift toward the positive polarity of the AO, but the evidence is less conclusive. Owing to the photochemical memory inherent in the ozone distribution, roughly half the ozone depletion during the NH summer months is linearly dependent on AO-related ozone losses incurred during the previous active season. Lower-tropospheric geopotential height falls over the Antarctic polar cap region are indicative of a drift toward the high index polarity of the Southern Hemisphere (SH) annular mode with no apparent seasonality. In contrast, the trend toward a cooling and strengthening of the SH stratospheric polar vortex peaks sharply during the stratosphere’s relatively short active season centered in November. The most pronounced SH ozone losses have occurred in September–October, one or two months prior to this active season. In both hemispheres, positive feedbacks involving ozone destruction, cooling, and a weakening of the wave-driven meridional circulation may be contributing to a delayed breakdown of the polar vortex and enhanced ozone losses during spring.

Propagation of planetary-scale disturbances from the lower into the upper atmosphere

1961-01-01

J. G. Charney , P. G. Drazin

Large losses of total ozone in Antarctica reveal seasonal ClOx/NOx interaction

1985-05-01

J. C. Farman , B. G. Gardiner , J. D. Shanklin

Stratospheric sink for chlorofluoromethanes: chlorine atom-catalysed destruction of ozone

1974-06-01

Mario J. Molina , F. S. Rowland

Tropical tropopause layer

2009-02-16

S. Fueglistaler , A. E. Dessler , Timothy J. Dunkerton +3 more

Observations of temperature, winds, and atmospheric trace gases suggest that the transition from troposphere to stratosphere occurs in a layer, rather than at a sharp “tropopause.” In the tropics, this … Observations of temperature, winds, and atmospheric trace gases suggest that the transition from troposphere to stratosphere occurs in a layer, rather than at a sharp “tropopause.” In the tropics, this layer is often called the “tropical tropopause layer” (TTL). We present an overview of observations in the TTL and discuss the radiative, dynamical, and chemical processes that lead to its time‐varying, three‐dimensional structure. We present a synthesis definition with a bottom at 150 hPa, 355 K, 14 km (pressure, potential temperature, and altitude) and a top at 70 hPa, 425 K, 18.5 km. Laterally, the TTL is bounded by the position of the subtropical jets. We highlight recent progress in understanding of the TTL but emphasize that a number of processes, notably deep, possibly overshooting convection, remain not well understood. The TTL acts in many ways as a “gate” to the stratosphere, and understanding all relevant processes is of great importance for reliable predictions of future stratospheric ozone and climate.

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Chemical kinetics and photochemical data for use in stratospheric modeling

1992-08-15

W. B. DeMore , J. J. Margitan , Mario J. Molina +6 more

As part of a series of evaluated sets, rate constants and photochemical cross sections compiled by the NASA Panel for Data Evaluation are provided. The primary application of the data … As part of a series of evaluated sets, rate constants and photochemical cross sections compiled by the NASA Panel for Data Evaluation are provided. The primary application of the data is in the modeling of stratospheric processes, with particular emphasis on the ozone layer and its possible perturbation by anthropogenic and natural phenomena. Copies of this evaluation are available from the Jet Propulsion Laboratory.

MSIS‐86 Thermospheric Model

1987-05-01

Alan E. Hedin

The MSIS‐86 empirical model of thermospheric temperature, density and composition uses new temperature and composition data from the Dynamics Explorer satellite to improve the representation of polar region morphology over … The MSIS‐86 empirical model of thermospheric temperature, density and composition uses new temperature and composition data from the Dynamics Explorer satellite to improve the representation of polar region morphology over that in the MSIS‐83 model. Terms were added or changed to better represent seasonal variations in the polar regions under both quiet and magnetically disturbed conditions. Local time variations in the magnetic activity effect were added. In addition a new species, atomic nitrogen, was added to the previous list of N 2 , O 2 , He, O, H, and Ar covered by the model.

Changes in biologically active ultraviolet radiation reaching the Earth's surface

1998-10-01

S. Madronich , Richard McKenzie , Lars Olof Björn +1 more

Radiative transfer for inhomogeneous atmospheres: RRTM, a validated correlated‐k model for the longwave

1997-07-01

E. J. Mlawer , Steven J. Taubman , P. Brown +2 more

A rapid and accurate radiative transfer model (RRTM) for climate applications has been developed and the results extensively evaluated. The current version of RRTM calculates fluxes and cooling rates for … A rapid and accurate radiative transfer model (RRTM) for climate applications has been developed and the results extensively evaluated. The current version of RRTM calculates fluxes and cooling rates for the longwave spectral region (10–3000 cm −1 ) for an arbitrary clear atmosphere. The molecular species treated in the model are water vapor, carbon dioxide, ozone, methane, nitrous oxide, and the common halocarbons. The radiative transfer in RRTM is performed using the correlated‐ k method: the k distributions are attained directly from the LBLRTM line‐by‐line model, which connects the absorption coefficients used by RRTM to high‐resolution radiance validations done with observations. Refined methods have been developed for treating bands containing gases with overlapping absorption, for the determination of values of the Planck function appropriate for use in the correlated‐ k approach, and for the inclusion of minor absorbing species in a band. The flux and cooling rate results of RRTM are linked to measurement through the use of LBLRTM, which has been substantially validated with observations. Validations of RRTM using LBLRTM have been performed for the midlatitude summer, tropical, midlatitude winter, subarctic winter, and four atmospheres from the Spectral Radiance Experiment campaign. On the basis of these validations the longwave accuracy of RRTM for any atmosphere is as follows: 0.6 W m −2 (relative to LBLRTM) for net flux in each band at all altitudes, with a total (10–3000 cm −1 ) error of less than 1.0 W m −2 at any altitude; 0.07 K d −1 for total cooling rate error in the troposphere and lower stratosphere, and 0.75 K d −1 in the upper stratosphere and above. Other comparisons have been performed on RRTM using LBLRTM to gauge its sensitivity to changes in the abundance of specific species, including the halocarbons and carbon dioxide. The radiative forcing due to doubling the concentration of carbon dioxide is attained with an accuracy of 0.24 W m −2 , an error of less than 5%. The speed of execution of RRTM compares favorably with that of other rapid radiation models, indicating that the model is suitable for use in general circulation models.

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Stratospheric ozone depletion: A review of concepts and history

1999-08-01

Susan Solomon

Stratospheric ozone depletion through catalytic chemistry involving man‐made chlorofluorocarbons is an area of focus in the study of geophysics and one of the global environmental issues of the twentieth century. … Stratospheric ozone depletion through catalytic chemistry involving man‐made chlorofluorocarbons is an area of focus in the study of geophysics and one of the global environmental issues of the twentieth century. This review presents a brief history of the science of ozone depletion and describes a conceptual framework to explain the key processes involved, with a focus on chemistry. Observations that may be considered as evidence (fingerprints) of ozone depletion due to chlorofluorocarbons are explored, and the related gas phase and surface chemistry is described. Observations of ozone and of chlorine‐related trace gases near 40 km provide evidence that gas phase chemistry has indeed currently depleted about 10% of the stratospheric ozone there as predicted, and the vertical and horizontal structures of this depletion are fingerprints for that process. More striking changes are observed each austral spring in Antarctica, where about half of the total ozone column is depleted each September, forming the Antarctic ozone hole. Measurements of large amounts of ClO, a key ozone destruction catalyst, are among the fingerprints showing that human releases of chlorofluorocarbons are the primary cause of this change. Enhanced ozone depletion in the Antarctic and Arctic regions is linked to heterogeneous chlorine chemistry that occurs on the surfaces of polar stratospheric clouds at cold temperatures. Observations also show that some of the same heterogeneous chemistry occurs on the surfaces of particles present at midlatitudes as well, and the abundances of these particles are enhanced following explosive volcanic eruptions. The partitioning of chlorine between active forms that destroy ozone and inert reservoirs that sequester it is a central part of the framework for our understanding of the 40‐km ozone decline, the Antarctic ozone hole, the recent Arctic ozone losses in particularly cold years, and the observation of record midlatitude ozone depletion after the major eruption of Mount Pinatubo in the early 1990s. As human use of chlorofluorocarbons continues to decrease, these changes throughout the ozone layer are expected to gradually reverse during the twenty‐first century.

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A New Look at Stratospheric Sudden Warmings. Part I: Climatology and Modeling Benchmarks

2007-02-01

Andrew Charlton‐Perez , Lorenzo M. Polvani

Abstract Stratospheric sudden warmings are the clearest and strongest manifestation of dynamical coupling in the stratosphere–troposphere system. While many sudden warmings have been individually documented in the literature, this study … Abstract Stratospheric sudden warmings are the clearest and strongest manifestation of dynamical coupling in the stratosphere–troposphere system. While many sudden warmings have been individually documented in the literature, this study aims at constructing a comprehensive climatology: all major midwinter warming events are identified and classified, in both the NCEP–NCAR and 40-yr ECMWF Re-Analysis (ERA-40) datasets. To accomplish this a new, objective identification algorithm is developed. This algorithm identifies sudden warmings based on the zonal mean zonal wind at 60°N and 10 hPa, and classifies them into events that do and do not split the stratospheric polar vortex. Major midwinter stratospheric sudden warmings are found to occur with a frequency of approximately six events per decade, and 46% of warming events lead to a splitting of the stratospheric polar vortex. The dynamics of vortex splitting events is contrasted to that of events where the vortex is merely displaced off the pole. In the stratosphere, the two types of events are found to be dynamically distinct: vortex splitting events occur after a clear preconditioning of the polar vortex, and their influence on middle-stratospheric temperatures lasts for up to 20 days longer than vortex displacement events. In contrast, the influence of sudden warmings on the tropospheric state is found to be largely insensitive to the event type. Finally, a table of dynamical benchmarks for major stratospheric sudden warming events is compiled. These benchmarks are used in a companion study to evaluate current numerical model simulations of the stratosphere.

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The Earth observing system microwave limb sounder (EOS MLS) on the aura Satellite

2006-04-28

J. W. Waters , L. Froidevaux , R. S. Harwood +7 more

The Earth Observing System Microwave Limb Sounder measures several atmospheric chemical species (OH, HO/sub 2/, H/sub 2/O, O/sub 3/, HCl, ClO, HOCl, BrO, HNO/sub 3/, N/sub 2/O, CO, HCN, CH/sub … The Earth Observing System Microwave Limb Sounder measures several atmospheric chemical species (OH, HO/sub 2/, H/sub 2/O, O/sub 3/, HCl, ClO, HOCl, BrO, HNO/sub 3/, N/sub 2/O, CO, HCN, CH/sub 3/CN, volcanic SO/sub 2/), cloud ice, temperature, and geopotential height to improve our understanding of stratospheric ozone chemistry, the interaction of composition and climate, and pollution in the upper troposphere. All measurements are made simultaneously and continuously, during both day and night. The instrument uses heterodyne radiometers that observe thermal emission from the atmospheric limb in broad spectral regions centered near 118, 190, 240, and 640 GHz, and 2.5 THz. It was launched July 15, 2004 on the National Aeronautics and Space Administration's Aura satellite and started full-up science operations on August 13, 2004. An atmospheric limb scan and radiometric calibration for all bands are performed routinely every 25 s. Vertical profiles are retrieved every 165 km along the suborbital track, covering 82/spl deg/S to 82/spl deg/N latitudes on each orbit. Instrument performance to date has been excellent; data have been made publicly available; and initial science results have been obtained.

Atmospheric Chemistry Experiment (ACE): Mission overview

2005-06-02

P. F. Bernath , C. T. McElroy , M. C. Abrams +7 more

SCISAT‐1, also known as the Atmospheric Chemistry Experiment (ACE), is a Canadian satellite mission for remote sensing of the Earth's atmosphere. It was launched into low Earth circular orbit (altitude … SCISAT‐1, also known as the Atmospheric Chemistry Experiment (ACE), is a Canadian satellite mission for remote sensing of the Earth's atmosphere. It was launched into low Earth circular orbit (altitude 650 km, inclination 74°) on 12 Aug. 2003. The primary ACE instrument is a high spectral resolution (0.02 cm −1 ) Fourier Transform Spectrometer (FTS) operating from 2.2 to 13.3 μm (750–4400 cm −1 ). The satellite also features a dual spectrophotometer known as MAESTRO with wavelength coverage of 285–1030 nm and spectral resolution of 1–2 nm. A pair of filtered CMOS detector arrays records images of the Sun at 0.525 and 1.02 μm. Working primarily in solar occultation, the satellite provides altitude profile information (typically 10–100 km) for temperature, pressure, and the volume mixing ratios for several dozen molecules of atmospheric interest, as well as atmospheric extinction profiles over the latitudes 85°N to 85°S. This paper presents a mission overview and some of the first scientific results.

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Annular Modes in the Extratropical Circulation. Part I: Month-to-Month Variability*

2000-03-01

David W. J. Thompson , John M. Wallace

The leading modes of variability of the extratropical circulation in both hemispheres are characterized by deep, zonally symmetric or “annular” structures, with geopotential height perturbations of opposing signs in the … The leading modes of variability of the extratropical circulation in both hemispheres are characterized by deep, zonally symmetric or “annular” structures, with geopotential height perturbations of opposing signs in the polar cap region and in the surrounding zonal ring centered near 45° latitude. The structure and dynamics of the Southern Hemisphere (SH) annular mode have been extensively documented, whereas the existence of a Northern Hemisphere (NH) mode, herein referred to as the Arctic Oscillation (AO), has only recently been recognized. Like the SH mode, the AO can be defined as the leading empirical orthogonal function of the sea level pressure field or of the zonally symmetric geopotential height or zonal wind fields. In this paper the structure and seasonality of the NH and SH modes are compared based on data from the National Centers for Environmental Prediction–National Center for Atmospheric Research reanalysis and supplementary datasets. The structures of the NH and SH annular modes are shown to be remarkably similar, not only in the zonally averaged geopotential height and zonal wind fields, but in the mean meridional circulations as well. Both exist year-round in the troposphere, but they amplify with height upward into the stratosphere during those seasons in which the strength of the zonal flow is conducive to strong planetary wave–mean flow interaction: midwinter in the NH and late spring in the SH. During these “active seasons,” the annular modes modulate the strength of the Lagrangian mean circulation in the lower stratosphere, total column ozone and tropopause height over mid- and high latitudes, and the strength of the trade winds of their respective hemispheres. The NH mode also contains an embedded planetary wave signature with expressions in surface air temperature, precipitation, total column ozone, and tropopause height. It is argued that the horizontal temperature advection by the perturbed zonal-mean zonal wind field in the lower troposphere is instrumental in forcing this pattern. A companion paper documents the striking resemblance between the structure of the annular modes and observed climate trends over the past few decades.

Climate Change from 1850 to 2005 Simulated in CESM1(WACCM)

2013-05-09

D. R. Marsh , Michael Mills , Douglas E. Kinnison +3 more

Abstract The NCAR Community Earth System Model (CESM) now includes an atmospheric component that extends in altitude to the lower thermosphere. This atmospheric model, known as the Whole Atmosphere Community … Abstract The NCAR Community Earth System Model (CESM) now includes an atmospheric component that extends in altitude to the lower thermosphere. This atmospheric model, known as the Whole Atmosphere Community Climate Model (WACCM), includes fully interactive chemistry, allowing, for example, a self-consistent representation of the development and recovery of the stratospheric ozone hole and its effect on the troposphere. This paper focuses on analysis of an ensemble of transient simulations using CESM1(WACCM), covering the period from the preindustrial era to present day, conducted as part of phase 5 of the Coupled Model Intercomparison Project. Variability in the stratosphere, such as that associated with stratospheric sudden warmings and the development of the ozone hole, is in good agreement with observations. The signals of these phenomena propagate into the troposphere, influencing near-surface winds, precipitation rates, and the extent of sea ice. In comparison of tropospheric climate change predictions with those from a version of CESM that does not fully resolve the stratosphere, the global-mean temperature trends are indistinguishable. However, systematic differences do exist in other climate variables, particularly in the extratropics. The magnitude of the difference can be as large as the climate change response itself. This indicates that the representation of stratosphere–troposphere coupling could be a major source of uncertainty in climate change projections in CESM.

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The HITRAN2016 molecular spectroscopic database

2017-07-05

Iouli E. Gordon , Laurence S. Rothman , C. Hill +7 more

This paper describes the contents of the 2016 edition of the HITRAN molecular spectroscopic compilation. The new edition replaces the previous HITRAN edition of 2012 and its updates during the … This paper describes the contents of the 2016 edition of the HITRAN molecular spectroscopic compilation. The new edition replaces the previous HITRAN edition of 2012 and its updates during the intervening years. The HITRAN molecular absorption compilation is composed of five major components: the traditional line-by-line spectroscopic parameters required for high-resolution radiative-transfer codes, infrared absorption cross-sections for molecules not yet amenable to representation in a line-by-line form, collision-induced absorption data, aerosol indices of refraction, and general tables such as partition sums that apply globally to the data. The new HITRAN is greatly extended in terms of accuracy, spectral coverage, additional absorption phenomena, added line-shape formalisms, and validity. Moreover, molecules, isotopologues, and perturbing gases have been added that address the issues of atmospheres beyond the Earth. Of considerable note, experimental IR cross-sections for almost 300 additional molecules important in different areas of atmospheric science have been added to the database. The compilation can be accessed through www.hitran.org. Most of the HITRAN data have now been cast into an underlying relational database structure that offers many advantages over the long-standing sequential text-based structure. The new structure empowers the user in many ways. It enables the incorporation of an extended set of fundamental parameters per transition, sophisticated line-shape formalisms, easy user-defined output formats, and very convenient searching, filtering, and plotting of data. A powerful application programming interface making use of structured query language (SQL) features for higher-level applications of HITRAN is also provided.

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Nitrous Oxide (N 2 O): The Dominant Ozone-Depleting Substance Emitted in the 21st Century

2009-08-28

A. R. Ravishankara , J. S. Daniel , R. W. Portmann

By comparing the ozone depletion potential-weighted anthropogenic emissions of N2O with those of other ozone-depleting substances, we show that N2O emission currently is the single most important ozone-depleting emission and … By comparing the ozone depletion potential-weighted anthropogenic emissions of N2O with those of other ozone-depleting substances, we show that N2O emission currently is the single most important ozone-depleting emission and is expected to remain the largest throughout the 21st century. N2O is unregulated by the Montreal Protocol. Limiting future N2O emissions would enhance the recovery of the ozone layer from its depleted state and would also reduce the anthropogenic forcing of the climate system, representing a win-win for both ozone and climate.

The ozone monitoring instrument

2006-04-28

P. F. Levelt , G. H. J. van den Oord , Marcel Dobber +6 more

The Ozone Monitoring Instrument (OMI) flies on the National Aeronautics and Space Administration's Earth Observing System Aura satellite launched in July 2004. OMI is a ultraviolet/visible (UV/VIS) nadir solar backscatter … The Ozone Monitoring Instrument (OMI) flies on the National Aeronautics and Space Administration's Earth Observing System Aura satellite launched in July 2004. OMI is a ultraviolet/visible (UV/VIS) nadir solar backscatter spectrometer, which provides nearly global coverage in one day with a spatial resolution of 13 km/spl times/24 km. Trace gases measured include O/sub 3/, NO/sub 2/, SO/sub 2/, HCHO, BrO, and OClO. In addition, OMI will measure aerosol characteristics, cloud top heights, and UV irradiance at the surface. OMI's unique capabilities for measuring important trace gases with a small footprint and daily global coverage will be a major contribution to our understanding of stratospheric and tropospheric chemistry and climate change. OMI's high spatial resolution is unprecedented and will enable detection of air pollution on urban scale resolution. In this paper, the instrument and its performance will be discussed.

Increase in tropospheric nitrogen dioxide over China observed from space

2005-08-31

Andreas Richter , John P. Burrows , Hendrik Nüß +2 more

The HITRAN molecular spectroscopic database: edition of 2000 including updates through 2001

2003-05-13

Laurence S. Rothman , A. Barbe , D. Chris Benner +7 more

The Global Ozone Monitoring Experiment (GOME): Mission Concept and First Scientific Results

1999-01-01

John P. Burrows , Mark Weber , Michael Buchwitz +7 more

The Global Ozone Monitoring Experiment (GOME) is a new instrument aboard the European Space Agency’s (ESA) Second European Remote Sensing Satellite (ERS-2), which was launched in April 1995. The main … The Global Ozone Monitoring Experiment (GOME) is a new instrument aboard the European Space Agency’s (ESA) Second European Remote Sensing Satellite (ERS-2), which was launched in April 1995. The main scientific objective of the GOME mission is to determine the global distribution of ozone and several other trace gases, which play an important role in the ozone chemistry of the earth’s stratosphere and troposphere. GOME measures the sunlight scattered from the earth’s atmosphere and/or reflected by the surface in nadir viewing mode in the spectral region 240–790 nm at a moderate spectral resolution of between 0.2 and 0.4 nm. Using the maximum 960-km across-track swath width, the spatial resolution of a GOME ground pixel is 40 × 320 km2 for the majority of the orbit and global coverage is achieved in three days after 43 orbits. Operational data products of GOME as generated by DLR-DFD, the German Data Processing and Archiving Facility (D-PAF) for GOME, comprise absolute radiometrically calibrated earthshine radiance and solar irradiance spectra (level 1 products) and global distributions of total column amounts of ozone and NO2 (level 2 products), which are derived using the DOAS approach (Differential Optical Absorption Spectroscopy). (Under certain conditions and some restrictions, the operational data products are publically available from the European Space Agency via the ERS Helpdesk.) In addition to the operational data products, GOME has delivered important information about other minor trace gases such as OClO, volcanic SO2, H2CO from biomass burning, and tropospheric BrO. Using an iterative optimal estimation retrieval scheme, ozone vertical profiles can be derived from the inversion of the UV/VIS spectra. This paper reports on the GOME instrument, its operation mode, and the retrieval techniques, the latter with particular emphasis on DOAS (total column retrieval) and advanced optimal estimation (ozone profile retrieval). Observation of ozone depletion in the recent polar spring seasons in both hemispheres are presented. OClO observed by GOME under twilight conditions provides valuable information on the chlorine activation inside the polar vortex, which is believed to be responsible for the rapid catalytic destruction of ozone. Episodes of enhanced BrO in the Arctic, most likely contained in the marine boundary layer, were observed in early and late spring. Excess tropospheric nitrogen dioxide and ozone have been observed during the recent Indonesian fire in fall 1997. Formaldehyde could also clearly be identified by GOME and is known to be a by-product resulting from biomass burning.

Correcting for the Effects of Interstellar Extinction

1999-01-01

E. L. Fitzpatrick

This paper addresses the issue of how best to correct astronomical data for the wavelength-dependent effects of Galactic interstellar extinction. The main general features of extinction from the IR through … This paper addresses the issue of how best to correct astronomical data for the wavelength-dependent effects of Galactic interstellar extinction. The main general features of extinction from the IR through the UV are reviewed, along with the nature of observed spatial variations. The enormous range of extinction properties found in the Galaxy, particularly in the UV spectral region, is illustrated. Fortunately, there are some tight constraints on the wavelength dependence of extinction and some general correlations between extinction curve shape and interstellar environment. These relationships provide some guidance for correcting data for the effects of extinction. Several strategies for dereddening are discussed along with estimates of the uncertainties inherent in each method. In the Appendix, a new derivation of the wavelength dependence of an average Galactic extinction curve from the IR through the UV is presented, along with a new estimate of how this extinction law varies with the parameter R = A(V)/E(B-V). These curves represent the true monochromatic wavelength dependence of extinction and, as such, are suitable for dereddening IR--UV spectrophotometric data of any resolution, and can be used to derive extinction relations for any photometry system.

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The chemistry of the atmosphere and oceans

1979-01-01

Duncan F. Sibley

The HITRAN2020 molecular spectroscopic database

2021-09-27

Iouli E. Gordon , Laurence S. Rothman , Robert J. Hargreaves +7 more

The HITRAN database is a compilation of molecular spectroscopic parameters. It was established in the early 1970s and is used by various computer codes to predict and simulate the transmission … The HITRAN database is a compilation of molecular spectroscopic parameters. It was established in the early 1970s and is used by various computer codes to predict and simulate the transmission and emission of light in gaseous media (with an emphasis on terrestrial and planetary atmospheres). The HITRAN compilation is composed of five major components: the line-by-line spectroscopic parameters required for high-resolution radiative-transfer codes, experimental infrared absorption cross-sections (for molecules where it is not yet feasible for representation in a line-by-line form), collision-induced absorption data, aerosol indices of refraction, and general tables (including partition sums) that apply globally to the data. This paper describes the contents of the 2020 quadrennial edition of HITRAN. The HITRAN2020 edition takes advantage of recent experimental and theoretical data that were meticulously validated, in particular, against laboratory and atmospheric spectra. The new edition replaces the previous HITRAN edition of 2016 (including its updates during the intervening years). All five components of HITRAN have undergone major updates. In particular, the extent of the updates in the HITRAN2020 edition range from updating a few lines of specific molecules to complete replacements of the lists, and also the introduction of additional isotopologues and new (to HITRAN) molecules: SO, CH3F, GeH4, CS2, CH3I and NF3. Many new vibrational bands were added, extending the spectral coverage and completeness of the line lists. Also, the accuracy of the parameters for major atmospheric absorbers has been increased substantially, often featuring sub-percent uncertainties. Broadening parameters associated with the ambient pressure of water vapor were introduced to HITRAN for the first time and are now available for several molecules. The HITRAN2020 edition continues to take advantage of the relational structure and efficient interface available at www.hitran.org and the HITRAN Application Programming Interface (HAPI). The functionality of both tools has been extended for the new edition.

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The HITRAN 2008 molecular spectroscopic database

2009-02-27

Laurence S. Rothman , Iouli E. Gordon , A. Barbé +7 more

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The HITRAN2012 molecular spectroscopic database

2013-07-12

Laurence S. Rothman , Iouli E. Gordon , Yurii L. Babikov +7 more

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Climate Change 2021—The Physical Science Basis

2021-10-01

Abstract The Intergovernmental Panel on Climate Change (IPCC) is the United Nations body responsible for assessing the science related to climate change. The Sixth Report from IPCC Working Group 1 … Abstract The Intergovernmental Panel on Climate Change (IPCC) is the United Nations body responsible for assessing the science related to climate change. The Sixth Report from IPCC Working Group 1 published in August 2021 paints a very sombre picture for the future. This report was commented on in a news item by the International Science Council (ISC) on behalf of its members, of which IUPAC is a founding member.

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Chemistry of the Upper and Lower Atmosphere

2000-01-01

Triple oxygen isotope composition of CO2 in the upper troposphere and stratosphere

2025-06-25

Getachew Agmuas Adnew , Gerbrand Koren , Neha Mehendale +3 more | Atmospheric measurement techniques

Abstract. High-precision measurements of the triple oxygen isotope composition of CO2 (Δ′17O) can be used to estimate biosphere–atmosphere exchange of CO2, the residence time of tropospheric CO2, and stratosphere–troposphere exchange. … Abstract. High-precision measurements of the triple oxygen isotope composition of CO2 (Δ′17O) can be used to estimate biosphere–atmosphere exchange of CO2, the residence time of tropospheric CO2, and stratosphere–troposphere exchange. In this study, we report measurements of the Δ′17O(CO2) from air samples collected during two aircraft-based programmes, CARIBIC and StratoClim. CARIBIC (Civil Aircraft for the Regular Investigation of the atmosphere Based on an Instrument Container) provided air samples from numerous transcontinental flights in the upper troposphere–lower stratosphere region. StratoClim (Stratospheric and upper tropospheric processes for better climate predictions) conducted intensive campaigns with the high-altitude aircraft M55 Geophysica during the Asian summer monsoon anticyclone (ASMA), providing air samples from altitudes up to 21 km. Using high-precision Δ′17O measurements of the CARIBIC samples, we show that the N2O–Δ′17O correlation, previously observed in the stratosphere, extends to the upper troposphere. Moreover, we found no significant spatial or hemispheric differences in Δ′17O(CO2) for the upper-tropospheric samples collected during the CARIBIC programme. However, in many of the StratoClim samples, with significant stratospheric contributions, we observed a much lower N2O–Δ′17O slope compared to CARIBIC samples and previous publications. This deviation is attributed to change in eddy diffusion above the tropopause within the ASMA, confirming previously published model calculations. These samples provide the first experimental evidence that differences in vertical mixing/transport can lead to significantly different N2O–Δ′17O slopes. High-precision Δ′17O measurements can identify ejections of tropospheric air into the stratosphere based on the slope of the N2O–Δ′17O correlation, as both tracers have chemical lifetimes longer than their transport times. Furthermore, we use the Δ′17O measurements from the lower stratosphere and the upper troposphere to estimate global stratospheric production and surface removal of the isotope tracer Δ′17O. The removal estimate is then used to derive an independent estimate of global vegetation exchange of CO2, confirming earlier estimates based on surface level Δ′17O measurements.

Assimilation of volcanic sulfur dioxide products from IASI and TROPOMI into the chemical transport model MOCAGE: case study of the 2021 La Soufrière Saint Vincent eruption with the March 2022 version of MOCAGE

2025-06-24

Mickaël Bacles , Jonathan Améric , Vincent Guidard | Atmospheric measurement techniques

Abstract. Sulfur dioxide emitted during volcanic eruptions can be hazardous for aviation safety. As part of their activities, the Volcanic Ash Advisory Centres (VAACs) are therefore interested in the real-time … Abstract. Sulfur dioxide emitted during volcanic eruptions can be hazardous for aviation safety. As part of their activities, the Volcanic Ash Advisory Centres (VAACs) are therefore interested in the real-time atmospheric monitoring of this gas. A recent development aims at improving the forecasts of volcanic sulfur dioxide quantities made by the MOCAGE (Modèle de Chimie Atmosphérique à Grande Échelle) chemistry transport model. For this purpose, observations from both TROPOMI (Tropospheric Monitoring Instrument) and IASI (Infrared Atmospheric Sounding Interferometer; B and C) located on separate polar-orbiting satellites are assimilated into the model. These sulfur dioxide measurements are based on the eruption event of the La Soufrière Saint Vincent volcano in April 2021. Observations from OMI (Ozone Monitoring Instrument) are considered validation data. The resulting assimilation experiments show that the combined assimilation of IASI and TROPOMI observations always leads to a better forecast compared to the independent assimilation of data from each instrument. Sulfur dioxide atmospheric field forecasts are better when the available observations are numerous and cover a long time window.

Assessing Total and Tropospheric Ozone via IKFS-2 Infrared Measurements on Meteor-M No. 2

2025-06-24

A. V. Polyakov , Ya. A. Virolainen , G. M. Nerobelov +4 more | Atmosphere

Stratospheric ozone shields life on Earth from harmful ultraviolet radiation and plays a crucial role in climate formation, while tropospheric ozone is a pollutant and greenhouse gas. Satellite methods based … Stratospheric ozone shields life on Earth from harmful ultraviolet radiation and plays a crucial role in climate formation, while tropospheric ozone is a pollutant and greenhouse gas. Satellite methods based on measurements of outgoing thermal radiation are the only methods that provide information on global ozone distribution, independent of solar illumination. Since about 90% of atmospheric ozone is concentrated in the stratosphere, ozone total column measurements can be used as stratospheric ozone measurements. We present techniques for deriving information on total ozone columns (TOCs) and tropospheric ozone columns (TrOCs) from spectra of outgoing thermal radiation measured by the IKFS-2 instrument aboard the Meteor-M No. 2 satellite. The techniques are based on principal component analysis and the artificial neural network approach, providing high accuracy in TOC (less than 3%) and TrOC (within 2–4 DU) retrieval in accordance with the WMO requirements for the quality of satellite measurements.

Comment on “Unveiling the Atmospheric Oxidation of Hexafluoroisobutylene, (CF3)2C═CH2, with Cl Atom, NO3 Radical, and O3 Molecule”

2025-06-24

Claus J. Nielsen | The Journal of Physical Chemistry A

Variability of satellite-based tropospheric nitrogen dioxide column abundance in the last 20 years over ten Mexican metropolitan areas measured by the Ozone Monitoring Instrument

2025-06-23

Claudia Rivera , Karel Aldrin Sánchez Hernández | Discover Atmosphere

Persistent emissions of ozone-depleting carbon tetrachloride from China during 2011–2021

2025-06-23

Minde An , Bo Yao , Luke M. Western +7 more | Nature Geoscience

UV photodissociation of H_2^+ in interstellar radiation fields: Shape resonances and astrophysical implications

2025-06-23

Yu Kun Yang , Yu Tang , Xing Guang Su +7 more | Astronomy and Astrophysics

Prior investigations into the photodissociation dynamics of the hydrogen molecular ion (H_ ) have frequently neglected the impact of shape resonances, which could potentially lead to inaccuracies in astrophysical modeling. … Prior investigations into the photodissociation dynamics of the hydrogen molecular ion (H_ ) have frequently neglected the impact of shape resonances, which could potentially lead to inaccuracies in astrophysical modeling. This study systematically explores the photodissociation cross sections of H_ with a rigorous consideration of shape resonances. We aim to elucidate comprehensively the photodissociation mechanisms by accurately accounting for transitions from the electronic ground state $1^2Σ_ g $ to multiple electronically excited states. Our results provide updated, precise cross-sectional data essential for refining chemical evolution models of interstellar environments and for rectifying previous methodological oversights. We employed high-level ab initio calculations based on the multireference single- and double-excitation configuration interaction (MRDCI) method to determine the electronic structure of the H_ ion accurately. The photodissociation cross sections were calculated under the assumption of local thermodynamic equilibrium (LTE) across photon wavelengths ranging from $25$ nm to the dissociation threshold, incorporating contributions from the majority of rovibrational states of the ground electronic state. Particular attention was given to analyzing the effects of shape resonances, especially the significant role played by the 1^2Π_ state near the spectral region of the Lyman α line. Our computed cross sections clearly demonstrate that shape resonances substantially influence the photodissociation dynamics of H_ near the Lyman α line. The contribution from the 1^2Π_ excited state prominently shapes the spectral absorption features around the Lyman α region. These refined theoretical results offer substantial improvements over previous datasets, delivering the precise spectral information necessary for astrophysical simulations, modeling ultraviolet-driven chemical processes in interstellar media, and enhancing our understanding of photochemical dynamics in the early universe.

WITHDRAWN: Comprehensive assessment of atmospheric interactions between Criegee intermediate and simplest Imine (CH2NH) in gas and aqueous phase environments

2025-06-23

Manas Ranjan Dash , Naga Venkateswara , Mohamad Akbar Ali | Research Square (Research Square)

<title>Abstract</title> The full text of this preprint has been withdrawn by the authors due to author disagreement with the posting of the preprint. Therefore, the authors do not wish this … <title>Abstract</title> The full text of this preprint has been withdrawn by the authors due to author disagreement with the posting of the preprint. Therefore, the authors do not wish this work to be cited as a reference. Questions should be directed to the corresponding author.

An Integrated Analysis of Ozone and Carbon Monoxide Over the Western Pacific Using Satellite and Aircraft Measurements During the ACCLIP Summer Campaign 2022

2025-06-21

Juseon Bak , Joowan Kim , Ja‐Ho Koo +7 more | Journal of Geophysical Research Atmospheres

Abstract The western Pacific exhibited a complex interplay of monsoonal dynamics and transport during the Asian Summer Monsoon Chemical & Climate Impact Project (ACCLIP) airborne field campaign in summer 2022. … Abstract The western Pacific exhibited a complex interplay of monsoonal dynamics and transport during the Asian Summer Monsoon Chemical & Climate Impact Project (ACCLIP) airborne field campaign in summer 2022. We analyze in situ observations of ozone (O 3 ) and carbon monoxide (CO) from 29 research flights—profiling over South Korea and cruising over the western Pacific —and balloon soundings in South Korea and Taiwan. In the upper troposphere (UT), a twofold enhancement in CO was observed across the mid‐latitudes of the western Pacific, driven by large‐scale uplift and outflow associated with the Asian Summer Monsoon (ASM) system. Observational evidence of enhanced UT O 3 in conjunction with its primary precursor, nitrogen dioxide (NO 2 ), was also presented. Satellite observations from the TROPOspheric Monitoring Instrument (TROPOMI) and Microwave Limb Sounder (MLS) were integrated with two selected flight cases to explore transport events and to provide broader spatial context. On July 31, the ASM anticyclone manifested in two distinct modes, South Asia High (SAH) and Western Pacific High (WPH). The SAH was filled with polluted air masses uplifted from the Asian boundary layer while the WPH was sustained by deep maritime convection. Both flight and satellite data captured polluted air parcels over the tropical western Pacific that had detached from the “main” anticyclonic eddy. By examining the case on August 6, we observed that the western Pacific was strongly modulated by low‐level westerlies and the eastward extension of the ASM anticyclone and isentropic mixing near the tropopause.

Atmospheric Boundary Layer and Tropopause Retrievals from FY-3/GNOS-II Radio Occultation Profiles

2025-06-21

Shaocheng Zhang , Youlin He , Sheng Guo +1 more | Remote Sensing

The atmospheric boundary layer (ABL) and tropopause play critical roles in weather formation and climate change. This study initially focuses on the ABL height (ABLH), tropopause height (TPH), and temperature … The atmospheric boundary layer (ABL) and tropopause play critical roles in weather formation and climate change. This study initially focuses on the ABL height (ABLH), tropopause height (TPH), and temperature (TPT) retrieved from the integrated radio occultation (RO) profiles from FY-3E, FY-3F, and FY-3G satellites during September 2022 to August 2024. All three FY-3 series satellites are equipped with the RO payload of Global Navigation Satellite System Radio Occultation Sounder-II (GNOS-II), which includes open-loop tracking RO observations from the BeiDou navigation satellite system (BDS) and the Global Positioning System (GPS). The wavelet covariance transform method was used to determine the ABL top, and the temperature lapse rate was applied to judge the tropopause. Results show that the maximum ABL detection rate of FY-3/GNOS-II RO can reach up to 76% in the subtropical eastern Pacific, southern hemisphere Atlantic, and eastern Indian Ocean. The ABLH is highly consistent with the collocated radiosonde observations and presents distinct seasonal variations. The TPH retrieved from FY-3/GNOS-II RO profiles is in agreement with the radiosonde-derived TPH, and both TPH and TPT from RO profiles display well-defined spatial structures. From 45°S to 45°N and south of 55°S, the annual cycle of the TPT is negatively correlated with the TPH. This study substantiates the promising performance of FY-3/GNOS-II RO measurements in observing the ABL and tropopause, which can be incorporated into the weather and climate systems.

Zonal Asymmetry in Ozone Variations Over Antarctic Stations During the Life Cycle of Sudden Stratospheric Warmings

2025-06-21

Ruixian Yu , Asen Grytsai , Gennadi Milinevsky +6 more | Journal of Geophysical Research Atmospheres

Abstract The zonal asymmetry in the Antarctic total ozone column (TOC) has been widely studied in recent decades. However, little is known about how spatially dependent the TOC response is … Abstract The zonal asymmetry in the Antarctic total ozone column (TOC) has been widely studied in recent decades. However, little is known about how spatially dependent the TOC response is to sudden stratospheric warmings (SSWs). This paper analyzes the connection of zonally asymmetric variations of TOC with SSWs in September 1988, 2002, and 2019. The analysis is based on time series for 16 Antarctic research stations, gridded fields (MSR‐2 TOC data), and the amplitude of zonal waves 1 and 2 in geopotential height (MERRA‐2 reanalysis). We use a superposed epoch analysis for ±60‐day time lags relative to the SSW central date to capture the main stages of the SSW life cycle. According to the TOC asymmetry pattern, a division between the Eastern Hemisphere (EH) and Western Hemisphere (WH) stations is used. The main results are zonally asymmetric variations in TOC anomalies near the SSW onset with the stronger (weaker) maximum in EH (WH), statistically significant at the 95% (89%) confidence level; precursor properties of the persistently growing positive anomalies in EH, and difference in timing of response maxima at day 0 in EH and day 7 in WH. These are previously unknown regional manifestations of Antarctic TOC anomalies. The results reveal statistically significant indicators of the possible SSW onset with a 1–2 weeks lead time. The dominant role of wave 1 and the zonally asymmetric Brewer–Dobson circulation in the observed EH–WH asymmetry is discussed.

Chlorinated very short-lived substances offset the long-term reduction of inorganic stratospheric chlorine

2025-06-20

Kimberlee Dubé , Susann Tegtmeier , Adam Bourassa +6 more | Communications Earth & Environment

Springtime UTLS Ozone Variability in East Asia: Insights From 16 Years of IASI Observations (2008–2023)

2025-06-20

C. H. Kim , Joowan Kim , Jae‐Heung Park +7 more | Journal of Geophysical Research Atmospheres

Abstract We investigated the springtime variability of ozone in the upper troposphere and lower stratosphere (UTLS) over East Asia using data from the Infrared Atmospheric Sounding Interferometer (IASI) onboard the … Abstract We investigated the springtime variability of ozone in the upper troposphere and lower stratosphere (UTLS) over East Asia using data from the Infrared Atmospheric Sounding Interferometer (IASI) onboard the Metop satellite series (Metop‐A, Metop‐B, and Metop‐C), complemented with ozonesonde observations and MERRA‐2 reanalysis data. The accuracy of the IASI ozone profiles was confirmed through validation against ozonesonde measurements, demonstrating their reliability for monitoring UTLS ozone dynamics. An empirical orthogonal function analysis revealed that the first principal component explained more than half of the variance in UTLS ozone during springtime, with strong positive correlations in regions influenced by the East Asian jet stream (EAJS). The analysis showed that the strengthening of the jet stream was associated with increased ozone concentrations, likely driven by enhanced baroclinic wave activity and stratospheric intrusion. Moreover, the intensification of the EAJS was associated with strengthening of the local Hadley Cells and the meridional temperature gradient over the upstream region even during springtime.

Multiscale Dynamical Processes Shaping a Mixing Line

2025-06-20

Andreas Dörnbrack , Hans‐Christoph Lachnitt , Peter Hoor +1 more | Journal of Geophysical Research Atmospheres

Abstract The paper discusses multiscale dynamical processes shaping a mixing line in the upper troposphere/lower stratosphere (UTLS). It focuses on aircraft observations above southern Scandinavia during a mountain wave event … Abstract The paper discusses multiscale dynamical processes shaping a mixing line in the upper troposphere/lower stratosphere (UTLS). It focuses on aircraft observations above southern Scandinavia during a mountain wave event and how they can be analyzed based on dynamic variables and the trace gases O and CO. This study aims to identify the irreversible component of the stratosphere‐troposphere exchange. It was shown that the overall shape of the mixing line is determined by the large‐scale and mesoscale atmospheric conditions in the UTLS. Especially, the wide range of values along the flight tracks causes a compact, almost linear tracer‐tracer relation between O and CO. Only motion components with scales less than 4 km lead to the observed scatter around the mixing line. The anisotropic and patchy nature of the observed turbulence is responsible for this scatter in O and CO. The turbulence analysis reveals different scaling laws for the power spectra upstream, over the ridge and downstream of the mountains that lead to energy dissipation and irreversible mixing. The study suggests that turbulence dynamics may follow a cycle starting with 3D homogeneous isotropic turbulence upstream, transitioning to anisotropic turbulence over the ridge and further downstream. This transition is attributed to an interplay between turbulent eddies and internal gravity waves.

Modern Earth-like Chemical Disequilibrium Biosignatures are Challenging to Constrain through Spectroscopic Retrievals

2025-06-19

Amber V. Young , Tyler D. Robinson , Joshua Krissansen‐Totton +4 more | The Astrophysical Journal

Abstract Robust exoplanet characterization studies are underway, and the community is looking ahead toward developing observational strategies to search for life beyond our solar system. With the development of life … Abstract Robust exoplanet characterization studies are underway, and the community is looking ahead toward developing observational strategies to search for life beyond our solar system. With the development of life detection approaches like searching for atmospheric chemical species indicative of life, chemical disequilibrium has also been proposed as a potentially key signature for life. Chemical disequilibrium can arise from the production of waste gases due to biological processes and can be quantified using a metric known as the available Gibbs free energy. The main goal of this study was to explore the detectability of chemical disequilibrium for a modern Earth-like analog. Atmospheric retrievals coupled to a thermodynamics model were used to determine posterior distributions for the available Gibbs free energy given simulated observations at various noise levels. In reflected light, chemical disequilibrium signals were difficult to detect and limited by the constraints on the CH 4 abundance, which was challenging to constrain for a modern Earth case with simulated observations spanning ultraviolet through near-infrared wavelengths with V band signal-to-noise ratios of 10, 20, and 40. For a modern Earth analog orbiting a late-type M dwarf, we simulated transit observations with the James Webb Space Telescope Mid-Infrared Instrument and found that tight constraints on the available Gibbs free energy can be achieved, but only at extremely low noise on the order of several parts per million. This study serves as further proof of concept for remotely inferring chemical disequilibrium biosignatures and should be included in continuing to build life detection strategies for future exoplanet characterization missions.

Clouds Can Enhance Direct-imaging Detection of O2 and O3 on Terrestrial Exoplanets

2025-06-18

Huanzhou Yang , Maoxu Hu , Dorian S. Abbot | The Astrophysical Journal

Abstract Clouds are often considered a highly uncertain barrier for detecting biosignatures on exoplanets, especially given intuition gained from transit surveys. However, for direct-imaging reflected light observations, clouds could increase … Abstract Clouds are often considered a highly uncertain barrier for detecting biosignatures on exoplanets, especially given intuition gained from transit surveys. However, for direct-imaging reflected light observations, clouds could increase the observational signal by increasing reflected light. Here we constrain the impact of clouds on the detection of O 2 and O 3 by a direct-imaging telescope such as the Habitable Worlds Observatory (HWO) using observations simulated with the Planetary Spectrum Generator (PSG). We first perform sensitivity tests to show that low clouds enhance O 2 and O 3 detectability while high clouds diminish it, and the effect is greater when cloud particles are smaller. We next apply clouds produced by the cloud microphysics model Community Aerosol and Radiation Model for Atmospheres with varied planetary parameters and clouds drawn from observations of different types of clouds on Earth to PSG. We find that clouds are likely to increase the signal-to-noise ratio of O 2 and O 3 for terrestrial exoplanets under a wide range of scenarios. This work provides important constraints on the impact of clouds on observations by telescopes including HWO.

Stratospheric Aerosol Intervention experiment for the Chemistry–Climate Model Initiative

2025-06-18

Simone Tilmes , Ewa Bednarz , Andrin Jörimann +4 more | Atmospheric chemistry and physics

Abstract. A new Stratospheric Aerosol Intervention (SAI) experiment has been designed for the Chemistry–Climate Model Initiative (CCMI-2022) to assess the impacts of SAI on stratospheric chemistry and dynamical responses and … Abstract. A new Stratospheric Aerosol Intervention (SAI) experiment has been designed for the Chemistry–Climate Model Initiative (CCMI-2022) to assess the impacts of SAI on stratospheric chemistry and dynamical responses and inter-model differences using a constrained setup with a prescribed stratospheric aerosol distribution and fixed sea surface temperatures and sea ice. This paper serves a dual purpose: first, it describes the details of the experimental setup and the prescribed aerosol distribution and demonstrates the suitability of the simplified setup to study SAI impacts in the stratosphere in a multi-model framework. The experiment allows attributing inter-model differences to the resulting impacts on atmospheric chemistry, radiation, and dynamics rather than the model uncertainty arising from differences in aerosol forcing and feedbacks from the ocean and sea ice under SAI. Second, we use the Whole Atmosphere Community Climate Model (WACCM6) to compare the interactive stratospheric aerosol configuration with coupling to land, ocean, and sea ice used to produce the stratospheric aerosol distribution with the results of the constrained SAI experiment. With this, we identify and isolate the stratosphere-controlled SAI-induced impacts from those influenced by the coupling with the ocean. Overall, this comparison facilitates an advanced process-level understanding of the drivers of SAI-induced atmospheric responses. For example, we confirm earlier suggestions that the SAI-induced positive phase of the North Atlantic Oscillation in winter, with the corresponding winter warming over Eurasia and related changes, is driven by stratosphere–troposphere coupling. Future multi-model comparisons will thus provide an important contribution to upcoming scientific assessments of ozone depletion.

Fine-structure excitation of C_2O by He: Rate coefficients and astrophysical modeling

2025-06-18

A. Veselinova , F. Lique , Cheikh T Bop +2 more | Astronomy and Astrophysics

C(_2)O molecules are very good probes of oxygen chemistry in interstellar molecular clouds. The accurate derivation of their abundance requires non-local thermodynamic equilibrium (LTE) modeling of their emission spectra. This … C(_2)O molecules are very good probes of oxygen chemistry in interstellar molecular clouds. The accurate derivation of their abundance requires non-local thermodynamic equilibrium (LTE) modeling of their emission spectra. This study aims to provide highly accurate fine-structure resolved excitation rate coefficients of C(_2)O induced by collisions with He, enabling the improvement of the modeling of C(_2)O emission spectra in (cold) molecular clouds. A new potential energy surface for the C(_2)O--He system was calculated using the spin-restricted coupled-cluster method together with a complete atomic basis set extrapolation. Quantum scattering calculations were performed using the exact close-coupling approach, explicitly accounting for the fine structure of C(_2)O. Excitation calculations using a radiative transfer model were conducted in order to interpret observations of C(_2)O in TMC-1. Rate coefficients for transitions up to the rotational state (N = 20) and temperatures up to 70 K were obtained. The analysis of the excitation calculations revealed non-LTE effects of C_2O emission lines at typical densities of TMC-1 ((n( H _2) ∼ 10^4 cm )), reflecting a balance between collisional excitation and radiative relaxation. These effects significantly influence the derived physical conditions. The column density of C(_2)O in TMC-1 was estimated to be C_2O ≈ 9 ⋅ 10^ cm ). This refined value, derived using the newly calculated rate coefficients, highlights the limitations of previous LTE-based estimates and underscores the importance of non-LTE modeling. The new accurate collisional data enable a more confident modeling of C(_2)O excitation in interstellar clouds and improve the interpretation of C(_2)O emission spectra in molecular clouds, highlighting again the necessity of having accurate molecular data in astrochemical studies.

Ionization of CF3CH2F by Protons and Photons

2025-06-18

CÉSAR AUGUSTO COSTA DE CASTRO FERREIRA , J A Souza-Corrêa , Alexandre B. Rocha +1 more | Atoms

(1) Background: Ionizing radiation in the Earth’s atmosphere drives key chemical transformations affecting atmospheric composition. Despite their environmental relevance, experimental data on proton collisions with hydrofluorocarbons remain limited, and theoretical … (1) Background: Ionizing radiation in the Earth’s atmosphere drives key chemical transformations affecting atmospheric composition. Despite their environmental relevance, experimental data on proton collisions with hydrofluorocarbons remain limited, and theoretical models for total cross-sections and stopping power are still underdeveloped. (2) Methods: This study applies Rudd’s semiempirical model to calculate proton impact ionization cross-sections for the CF3CH2F molecule, considering contributions from both outer and inner electron shells. The model enables the estimation of differential cross-sections and the average energy of secondary electrons. In addition, we calculate the photoionization cross-sections using a discretized representation of the continuum—the so-called pseudo-spectrum—obtained through TDDFT with PBE0 as an exchange–correlation functional and compare it with the cross-section obtained for proton impact in the high-energy limit. (3) Results: The Rudd model proves highly adaptable and suitable for numerical applications. However, its validation is hindered by the scarcity of experimental data. Existing models, such as SRIM and Bethe–Bloch, show significant discrepancies due to their limited applicability at intermediate energies and lack of molecular structure consideration. (4) Conclusions: A comparison between the Rudd and BEB models reveals strong agreement in the analyzed energy range. This consistency stems from both models accounting for the molecular structure of the target, as well as from the fact that protons and electrons possess charges of the same magnitude, supporting a coherent description of ionization processes at these energies.

Muted Radiative Feedback of Stratospheric Water Vapor Found in a Multimodel Assessment

2025-06-17

R. He , Yi Huang | Journal of Geophysical Research Atmospheres

Abstract The strength of stratospheric water vapor (SWV) radiative feedback has been debated, primarily due to the compensating radiative effects of the associated stratospheric and tropospheric temperature adjustments, which are … Abstract The strength of stratospheric water vapor (SWV) radiative feedback has been debated, primarily due to the compensating radiative effects of the associated stratospheric and tropospheric temperature adjustments, which are primarily triggered by radiation process. In this study, we calculate the SWV radiative feedback in the CMIP6 model ensemble in a quadrupling CO 2 experiment. Specifically, we compare the results of two quantifications: one accounting for the radiatively driven temperature adjustment in the stratosphere only and the other in the entire atmospheric column including both the stratosphere and the troposphere. The stratosphere‐adjusted feedback is found to be , but it reduces to with the full atmosphere adjustment, indicating the radiation process alone may lead to a muted overall SWV radiative effect, due to the stratospheric cooling and tropospheric warming simultaneously driven by the SWV radiative perturbation. This suggests that the radiative forcing of SWV is subject to an intrinsic and robust limiting effect. In addition, we analyze the intermodel spreads in the temperature adjustment and its radiative effect, and find the spreads primarily arise from the differences in SWV responses projected by GCMs, rather than the differences in their climatological states.

Overview of the Dependence of Atmospheric Tide Amplitudes on the Phases of Natural Tropical Oscillations based on MUAM simulations

2025-06-17

Andrey V. Koval , Ksenia A. Didenko , Tatiana S. Ermakova +3 more | Research Square (Research Square)

<title>Abstract</title> The dependence of atmospheric tide amplitudes on the phases of long-period tropical oscillations, specifically the Quasi-Biennial Oscillation (QBO) of zonal wind in the equatorial stratosphere and the El Niño–Southern … <title>Abstract</title> The dependence of atmospheric tide amplitudes on the phases of long-period tropical oscillations, specifically the Quasi-Biennial Oscillation (QBO) of zonal wind in the equatorial stratosphere and the El Niño–Southern Oscillation (ENSO), is examined. Numerical simulations of global atmospheric circulation are conducted using the MUAM nonlinear mechanistic atmospheric model under various scenarios incorporating different combinations of QBO/ENSO phases. The structures of migrating diurnal and semidiurnal tides with zonal wave numbers 1 and 2, respectively, as well as non-migrating diurnal and semidiurnal tides with zonal wave numbers 2 and 1, respectively, are calculated. The analysis is focused on the boreal winter season (January - February), the period of peak wave activity for planetary waves (PWs) that are involved in the nonlinear generation of non-migrating tides. The results demonstrate, in particular, that the migrating diurnal tide (DT1) is amplified during the westerly QBO phase (wQBO) and under La Niña conditions. For the semidiurnal migrating tide (SDT2), ENSO effects are found to be more pronounced than those of the QBO. During El Niño, the tide’s amplitude decreases in the equatorial region while increasing to the North and South of it, regardless of the QBO phase. Changes in non-migrating tides differ from those of migrating tides with similar periods, which is attributed to the altered wave activity of the stationary PW with zonal wave number 1 (SPW1). Nonlinear interactions between primary migrating tides and this wave generate non-migrating tides. The effect of strengthening/weakening of non-migrating diurnal tide (DT2) generation for different combinations of QBO/ENSO is demonstrated explicitly by considering the terms responsible for the nonlinear interaction of PW1 and DT1 in the balance equation of perturbed potential enstrophy. The numerical simulations performed under “idealized” conditions, isolating the effects of QBO and ENSO, allowed for the differentiation of the influences of these two oscillations. Such separation is challenging with observational data due to limited time series, which restricts sample size and thereby limits the statistical capacity needed to distinguish between these phenomena having close periods.

Spatiotemporal Variations of Ultraviolet Radiation Over the Xizang-Tibet Plateau Based on Stations Observations and Satellite Datasets

2025-06-16

Huangjie Kong , Jianguo Wang , Caiting Li +3 more | Atmospheric Environment

Lille spectroscopic database for astrophysically and atmospherically relevant molecules

2025-06-16

R. A. Motiyenko , L. Margulès | Astronomy and Astrophysics

Over past 15 years, we have accumulated a significant amount of data on rotational spectra of astrophysically and atmospherically relevant molecules. These data were mostly absent from main spectroscopic databases, … Over past 15 years, we have accumulated a significant amount of data on rotational spectra of astrophysically and atmospherically relevant molecules. These data were mostly absent from main spectroscopic databases, such as CDMS and the JPL catalog, and dispersed across the supplementary sections of various publications. The aim of the Lille Spectroscopic Database (LSD) is to consolidate the accumulated data from the PhLAM laboratory into a single accessible location, enhancing its availability to the scientific community, and to introduce several additional features that facilitate data utilization. The LSD is based on a relational database accessible via a Java application that provides front- and back-end features. The application provides data access through a standard web interface and via a set of simple application programming interface (API) functions primarily intended for queries from external tools. The LSD provides access to molecular spectral predictions with options for frequency units, intensity units, temperature, and frequency range limitations. The output also contains partition function values for a set of temperatures. We also present several challenges in the conversion of intensity units inherent to the data output format and in connection with statistical weights and partition function calculation.

Seasonal and Interannual Variation of the Interhemispheric Coupling During the Austral Winter in WACCM6

2025-06-14

Dai Koshin , N. M. Pedatella , Anne K. Smith | Journal of Geophysical Research Atmospheres

Abstract We investigate interhemispheric coupling (IHC) during the austral winter by examining global characteristics of the dynamical fields initiated by stratospheric warming in the Southern Hemisphere using output of the … Abstract We investigate interhemispheric coupling (IHC) during the austral winter by examining global characteristics of the dynamical fields initiated by stratospheric warming in the Southern Hemisphere using output of the Whole Atmosphere Community Climate Model version 6 covering 195 simulation years. About 100 events were extracted and analyzed, focusing on the seasonal and interannual variation of the IHC response in the Northern Hemisphere. The seasonal variation can be explained by differences in the background atmosphere. The upward shift and weakening of the gravity wave forcing during the IHC in September are opposite to the characteristics of July and August. However, the mean zonal wind and the momentum deposition of gravity waves in the northern middle atmosphere in September are also opposite to those in July and August. Together, these result in the same sign of the anomaly. Additionally, an interannual variation in the altitude of the warming in the northern polar region is also observed, with warmings split at 100 km. A warming that appears above 100 km is explained by an additional mechanism of gravity wave modulation, which drives the winter‐to‐summer circulation in the lower thermosphere, while a warming below 100 km corresponds to the weakening of the summer‐to‐winter circulation in the upper mesosphere. Correspondingly, no warming is observed near 100 km, where the circulation and its modulation are absent. This interannual variation of the IHC is influenced by the intraseasonal oscillation, which represents a similar meridional temperature structure in the global middle atmosphere.

Geostationary Satellites Total Ozone Observations: First Results on Ground‐Based Networks Validation Efforts for TEMPO and GEMS

2025-06-14

Xiaoyi Zhao , Debora Griffin , Vitali Fioletov +7 more | Geophysical Research Letters

Abstract The Tropospheric Emissions: Monitoring of Pollution (TEMPO) instrument, launched in April 2023, is North America's first geostationary air pollution monitoring satellite mission. Together with Asia's Geostationary Environment Monitoring Spectrometer … Abstract The Tropospheric Emissions: Monitoring of Pollution (TEMPO) instrument, launched in April 2023, is North America's first geostationary air pollution monitoring satellite mission. Together with Asia's Geostationary Environment Monitoring Spectrometer (GEMS) launched in 2020 and Europe's upcoming Sentinel‐4, TEMPO contributes to nearly global coverage provided by geostationary satellite constellation. TEMPO and GEMS offer hourly, high‐resolution data of ozone surpassing the once‐daily observations of instruments like the TROPOspheric Monitoring Instrument (TROPOMI) in temporal resolution. This study presents TEMPO's total ozone data, demonstrating TEMPO's ability to observe sudden changes in ozone and UV index. Furthermore, TEMPO and GEMS measurements are validated using ground‐based monitoring networks (Brewer, Dobson, and Pandora). Results show good agreement but also highlight latitude‐dependent discrepancies between the satellite and ground‐based data sets (−2% to 2% for TEMPO, −1% to −3% for GEMS). Findings are further validated using TROPOMI data and reanalysis models.

Coupled planetary wave dynamics in the polar stratosphere analyzed with potential enstrophy and eddy energy budgets

2025-06-13

Philip Rupp , Peter B. Hitchcock , Thomas Birner | Journal of the Atmospheric Sciences

Abstract Anomalies in the stratospheric polar vortex (SPV), such as sudden stratospheric warming (SSW) events, significantly impact surface weather patterns. While the influence of SSWs on the troposphere is robust … Abstract Anomalies in the stratospheric polar vortex (SPV), such as sudden stratospheric warming (SSW) events, significantly impact surface weather patterns. While the influence of SSWs on the troposphere is robust on average, individual events exhibit large variability, partly due to the substantial difference in dynamics and SPV evolution across events. Understanding the physical processes driving SSWs is therefore important. In this study, we investigate SPV dynamics, focusing on non-linear coupling between planetary wave modes. We use potential enstrophy and eddy total energy budget analyses to quantify the contributions of different physical processes to SPV evolution. These budget analysis frameworks are unique in being able to study the contribution of non-linear wave–wave interactions to the dynamical evolution of the SPV. When applying this framework to both an idealized simulation and re-analysis data of the 2003 SSW, we find that non-linear wave–wave interactions can play a crucial role during SSWs. In the idealized simulation, wave-2 structures emerge in the stratosphere without a prescribed wave-2 source, attributed to non-linear transfer of enstrophy and energy from wave-1 to wave-2. In the 2003 case study, interactions between wave-1 and wave-2 contribute to a displacement-to-split transition. We also find indications of quasi-linear coupling and upscale enstrophy transfer from wave-2 to wave-1 during this period. The use of the enstrophy budget analyses highlights the significant impact of non-linear wave–wave interactions in SPV transitions. These complex interactions contribute to the uniqueness of each SSW event and may help explain the variability observed across different SSWs.

The Impact of Stratospheric Intrusion on Surface Ozone in Urban Areas of the Northeastern Tibetan Plateau

2025-06-12

Mingge Li , Yawen Kong , Meng Fan +5 more | Atmosphere

In recent years, high-altitude cities with low emissions in western China have exhibited an upward trend in surface ozone (O3). Based on observations and reanalysis data, this study analyzed the … In recent years, high-altitude cities with low emissions in western China have exhibited an upward trend in surface ozone (O3). Based on observations and reanalysis data, this study analyzed the evolutionary characteristics and pollution mechanisms of ozone in Xining and quantified the impact of stratospheric intrusion. The results indicated that an upward trend in summer O3 was observed in Xining. A total of 29 ozone exceedance days were found. Potential exceedance days (>150 and >140 μg/m3) showed substantial increases from 2022 to 2023. Using a stratospheric intrusion to surface (SITS) event identification algorithm, 42 events were found in Xining, with an average duration of 8.4 h. Spring exhibited the highest event frequency (13 events) and longest average duration. SITS events contributed an average of 19.7% to surface ozone, significantly exacerbating local exceedance risks. A typical ozone pollution episode from 25 July to 3 August 2021 was analyzed. The peak O3 reached 170 μg/m3. Elevated temperature, intensified radiation, and unfavorable meteorological conditions synergistically promoted local photochemical ozone production and accumulation. Notably, a SITS event was simultaneously detected, elevating surface ozone by 24%, which confirmed that stratospheric intrusion was the main cause of pollution.

Systematic Evidence Map for the Per- and Polyfluoroalkyl Substances (PFAS) Universe

2025-06-12

Avanti V. Shirke , Elizabeth G. Radke , Ryan Jones +7 more | Environmental Health Perspectives

Per- and polyfluoroalkyl substances (PFAS) are a research priority for the U.S. Environmental Protection Agency (EPA). Because PFAS include thousands of structurally diverse chemicals, there is a pressing need for … Per- and polyfluoroalkyl substances (PFAS) are a research priority for the U.S. Environmental Protection Agency (EPA). Because PFAS include thousands of structurally diverse chemicals, there is a pressing need for identifying what data are available to assess the human health hazard of these compounds. We used systematic evidence map (SEM) methods to summarize the available epidemiological and mammalian bioassay evidence for ∿14,735 chemicals identified as PFAS by EPA's Center for Computational Toxicology and Exposure (CCTE). This work is a continuation of our previous 2022 and 2024 SEMs that inventoried evidence on a separate set of ∿500 PFAS. The Comprehensive PFAS Dashboard includes evidence identified from our past SEMs and completed EPA assessments. We conducted literature searches from peer-reviewed and gray literature sources to identify, screen, and inventory mammalian bioassay and epidemiological literature. A combination of manual review and machine learning software were utilized. A diverse array of potentially relevant supplemental content was also tracked, including mechanistic data, exposure-only studies, and studies informing chemical toxicokinetics and clearance. For each study meeting predefined population, exposure, comparator, and outcome (PECO) criteria, experimental design details and health endpoints evaluated were summarized in interactive web-based literature inventory visuals. Epidemiology studies and animal bioassay studies with ≥21-day exposure duration or reproductive/developmental study design proceeded to undergo a study evaluation for risk of bias and sensitivity, as well as detailed extraction of health endpoint data. Underlying data are publicly available and can be downloaded. Scientific database searches retrieved 152,205 references. After full-text screening, there were 347 mammalian bioassay and 44 epidemiological studies that met PECO criteria. The mammalian bioassay and epidemiological evidence assessed 99 and 30 individual PFAS, respectively (n = 18 PFAS with both). The epidemiological evidence assessed 15 health systems and the mammalian bioassay evidence assessed 16 health systems. Results from our 2022 and 2024 SEMs and completed EPA assessments are compiled into Comprehensive PFAS Dashboard. This dashboard is a resource for better understanding the currently available PFAS human health hazard data. It can be used as a tool for researchers and regulators interested in PFAS data gaps and research needs. Across all the data sources compiled into the Comprehensive PFAS Dashboard, only 1.4% (214/14,735) of PFAS had any mammalian bioassay or epidemiological data available. The vast majority of PFAS lack publicly available information about the potential human health effects of exposure to these chemicals.. https://doi.org/10.1289/EHP16952.

Is ozone a reliable proxy for molecular oxygen? II. The impact of N_2O on the O2-O3 relationship for Earth-like atmospheres

2025-06-10

Thea Kozakis , Michael Mendonca , A. Lars Buchhave +1 more | Astronomy and Astrophysics

Molecular oxygen ( will be an important molecule in the search for biosignatures in terrestrial planetary atmospheres in the coming decades. In particular combined with a reducing gas (e.g., methane) … Molecular oxygen ( will be an important molecule in the search for biosignatures in terrestrial planetary atmospheres in the coming decades. In particular combined with a reducing gas (e.g., methane) is considered strong evidence for disequilibrium caused by surface life. However, there are circumstances where it would be very difficult or impossible to detect in which case it has been suggested that ozone ( the photochemical product of could be used instead. Unfortunately, the relationship is highly nonlinear and dependent on the host star, as shown in detail in the first paper of this series. This paper further explores the relationship around G0V-M5V host stars, using climate and photochemistry modeling to simulate atmospheres while varying abundances of and nitrous oxide ( Nitrous oxide is of particular importance to the relationship not only because it is produced biologically, but because it is the primary source of nitrogen oxides ( which fuel the catalytic cycle, which destroys and the smog mechanism that produces In our models we varied the mixing ratio from 0.01-150% of the present atmospheric level (PAL) and abundances of 10% and 1000% PAL. We find that varying impacts the relationship differently depending strongly on both the host star and the amount of atmospheric Planets orbiting hotter hosts with strong UV fluxes efficiently convert into often depleting a significant amount of via faster catalytic cycles. However, for cooler hosts and low levels we find that increasing can lead to an increase in overall due to the smog mechanism producing in the lower atmosphere. Variations in result in significant changes in the amount of harmful UV reaching the surfaces of the model planets as well as the strength of the 9.6 μm emission spectral feature, demonstrating potential impacts on habitability and future observations.

Construction of Temperature Climate Data Records in the Upper Troposphere and Lower Stratosphere Using Multiple RO Missions From September 2006 to July 2023 at NESDIS/STAR

2025-06-09

Jun Zhou , Shu‐peng Ho , Xinjia Zhou +5 more | Journal of Geophysical Research Atmospheres

Abstract We develop a new monthly zonal mean climatology (MMC) in the upper troposphere and lower stratosphere from September 2006 to July 2023 using the dry temperature profiles from multiple … Abstract We develop a new monthly zonal mean climatology (MMC) in the upper troposphere and lower stratosphere from September 2006 to July 2023 using the dry temperature profiles from multiple global navigation satellite system (GNSS) radio occultation (RO) missions processed by the GNSS RO Science and Data Center (SDC) at the NOAA Center for Satellite Applications and Research (STAR). The multiple RO missions include Formosa Satellite Mission 3/Constellation Observing System for Meteorology, Ionosphere, and Climate (COSMIC‐1), SPIRE, and Meteorological Operational satellite (MetOp)‐A, ‐B, ‐C. We compare collocated profiles from multiple STAR‐processed RO missions to ensure the consistency of the data used in the construction of STAR MMC. Because the Constellation Observing System for Meteorology, Ionosphere, and Climate‐2 (COSMIC‐2) contains a noticeable temperature difference compared with other RO missions, we decided not to include it. We validate the robustness of the sampling error correction method through three reanalyses: ERA‐5, MERRA‐2, and JRA‐55. The result shows the uncertainty caused by using different reanalyses is negligible. This STAR MMC is then compared with the ROM SAF MMC and the MMC derived from these three reanalyses, exhibiting general consistency. Various climate signals, including quasi‐biennial oscillation (QBO) and El Niño–Southern Oscillation (ENSO), can be identified from STAR MMC. The global temperature trends from STAR MMC show a prominent warming of 0.310 ± 0.128 K/Decade in the upper troposphere and a robust cooling of −0.295 ± 0.145 K/Decade in the mid‐stratosphere. These results demonstrate that STAR MMC can capture climate signals and monitor long‐term climate change.

Scientific equipment for the space experiment “Sun-Terahertz”: methods for increasing the frequency selectivity of detectors

2025-06-06

Maxim Philippov | Izmeritel`naya Tekhnika

The future space experiment «Sun-Terahertz» is aimed at studying the Sun in the unexplored terahertz range, obtaining new data on the terahertz radiation of the Sun, solar active regions and … The future space experiment «Sun-Terahertz» is aimed at studying the Sun in the unexplored terahertz range, obtaining new data on the terahertz radiation of the Sun, solar active regions and solar fl ares. The scientific equipment being developed is a set of eight detectors sensitive to radiation of various frequencies in the range 0.4–12.0 THz. In this paper, we consider the expected spectral characteristics of scientific equipment and briefl y describe the method of their experimental verification by installing an additional cutoff filter. Two methods for increasing the frequency selectivity of detectors are considered. To assess the sensitivity of the detectors, an experiment was conducted to measure solar radiation using a single-channel model, which is a complete analogue of the detector of scientific equipment with the ability to replace bandpass terahertz filters. Also, a two-axis rotating platform and a cloud sensor were made for the single-channel model. Based on the results of the experimental verification, conclusions were made about the sensitivity of the detectors of scientific equipment and the possibility of improving the characteristics in terms of frequency selectivity. This article may be useful to experimenters involved in spectrometric scientific devices based on optoacoustic converters (Golay cell) and other sensitive elements.