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Engineering › Aerospace Engineering

Calibration and Measurement Techniques

Works Count: 54420

Description

This cluster of papers focuses on the radiometric calibration and performance monitoring of satellite sensors, particularly in relation to reflective solar bands and emissivity measurements. It also covers topics such as on-orbit performance, thermometry, and absolute radiometric calibration for climate monitoring purposes.

Keywords

Radiometric Calibration; On-Orbit Performance; Satellite Sensors; Reflective Solar Bands; Calibration Stability; Emissivity Measurements; Thermometry; Absolute Radiometric Calibration; Spectral Irradiance; Climate Monitoring

COLORIMETRIC DETERMINATION OF UREA

1945-02-01
Reginald M. Archibald

Theory of Reflectance and Emittance Spectroscopy

1993-09-24
Bruce Hapke
This book is aimed at students and researchers who wish to use reflectance and emittance as quantitative tools to measure the properties of surfaces and materials. It is intended primarily … This book is aimed at students and researchers who wish to use reflectance and emittance as quantitative tools to measure the properties of surfaces and materials. It is intended primarily for use in the interpretation of remote observations of the surfaces of the Earth and other planets, and it will also be useful to chemists, physicists, geologists, engineers and others who deal with particulate media. Topics include propagation and absorption of light in continuous media, reflection by smooth surfaces, scattering by spheres and irregular particles, reflectances and emissivities of particulate media, reflectance and emittance spectroscopy, and the polarization of light scattered by particulate media. Many examples of applications are given.
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Infrared optical properties of water and ice spheres

1968-01-01
William M. Irvine , James B. Pollack

SOLAR AND TERRESTRIAL RADIATION.<sup>19</sup>

1924-08-01
A. ÅGNSTRÖM

Proposed reference irradiance spectra for solar energy systems testing

2002-12-01
Christian A. Gueymard , D. Myers , Keith Emery

The absorption and dissociative or ionizing effect of monochromatic radiation in an atmosphere on a rotating earth

1931-01-01
S. C. Chapman
The absorption of monochromatic radiation from the sun in an atmosphere of which the density varies exponentially with height is considered; the energy of the radiation, or a definite fraction … The absorption of monochromatic radiation from the sun in an atmosphere of which the density varies exponentially with height is considered; the energy of the radiation, or a definite fraction of it, is supposed to dissociate or ionize the air, and the dissociation products are supposed to recombine with one another only, and not to diffuse away from the element in which they were formed. The resulting distribution of density of the dissociation products is determined, a constant recombination coefficient being assumed, while account is taken of the variation in rate of dissociation due to the earth's rotation. The results are illustrated by numerous diagrams, showing the density of the dissociation-products as a function of height, time, latitude and season.

MODIS: advanced facility instrument for studies of the Earth as a system

1989-03-01
V. V. Salomonson , William L. Barnes , Peter W. Maymon +2 more
The moderate resolution imaging spectrometer (MODIS) is discussed as an Earth-viewing sensor that is planned as a facility instrument for the Earth Observing System (Eos) scheduled to begin functioning in … The moderate resolution imaging spectrometer (MODIS) is discussed as an Earth-viewing sensor that is planned as a facility instrument for the Earth Observing System (Eos) scheduled to begin functioning in the mid-1990s. The MODIS is composed of two mutually supporting sensors that cover a swath width sufficient to provide nearly complete two-day global coverage from a polar-orbiting, sun-synchronous, serviceable platform. High signal-to-noise ratios are to be provided, e.g. 500 to 1 or greater with 10-12-bit quantization over the dynamic ranges of the spectral bands. MODIS' lifetime is expected to be about ten years. One of the MODIS sensors is termed MODIS-N, where N signifies nadir-viewing. The companion to MODIS-N is MODIS-T, where T signifies a tiltable field-of-view. The development of the MODIS facility from conceptual design studies (Phase-A) into detailed design studies (Phase-B) is discussed.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Analysis of Bi-Metal Thermostats

1925-09-01
S. Timoshenko
Get PDF Email Share Share with Facebook Tweet This Post on reddit Share with LinkedIn Add to CiteULike Add to Mendeley Add to BibSonomy Get Citation Copy Citation Text S. … Get PDF Email Share Share with Facebook Tweet This Post on reddit Share with LinkedIn Add to CiteULike Add to Mendeley Add to BibSonomy Get Citation Copy Citation Text S. Timoshenko, "Analysis of Bi-Metal Thermostats," J. Opt. Soc. Am. 11, 233-255 (1925) Export Citation BibTex Endnote (RIS) HTML Plain Text Citation alert Save article

Power Vectors: An Application of Fourier Analysis to the Description and Statistical Analysis of Refractive Error

1997-06-01
Larry N. Thibos , William Henry Wheeler , Douglas G. Horner
The description of sphero-cylinder lenses is approached from the viewpoint of Fourier analysis of the power profile. It is shown that the familiar sine-squared law leads naturally to a Fourier … The description of sphero-cylinder lenses is approached from the viewpoint of Fourier analysis of the power profile. It is shown that the familiar sine-squared law leads naturally to a Fourier series representation with exactly three Fourier coefficients, representing the natural parameters of a thin lens. The constant term corresponds to the mean spherical equivalent (MSE) power, whereas the amplitude and phase of the harmonic correspond to the power and axis of a Jackson cross-cylinder (JCC) lens, respectively. Expressing the Fourier series in rectangular form leads to the representation of an arbitrary sphero-cylinder lens as the sum of a spherical lens and two cross-cylinders, one at axis 0° and the other at axis 45°. The power of these three component lenses may be interpreted as (x,y,z) coordinates of a vector representation of the power profile. Advantages of this power vector representation of a sphero-cylinder lens for numerical and graphical analysis of optometric data are described for problems involving lens combinations, comparison of different lenses, and the statistical distribution of refractive errors.

The Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER): Data products for the high spatial resolution imager on NASA's Terra platform

2000-01-01
Michael J. Abrams
The Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) is a high spatial resolution, multispectral imager with along-track stereo capabilities scheduled for launch on the first NASA spacecraft of the … The Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) is a high spatial resolution, multispectral imager with along-track stereo capabilities scheduled for launch on the first NASA spacecraft of the Earth Observing System (Terra) in 1999. Data will be obtained in 14 spectral bands covering the visible through the thermal infrared wavelength region. A number of standard data products will be available to requesters through an on-line archival and processing system. Particular, user-specified data acquisitions will be possible through a Data Acquisition Request system.

Review of temperature measurement

2000-08-01
Peter Childs , J.R. Greenwood , Christopher Long
A variety of techniques are available enabling both invasive measurement, where the monitoring device is installed in the medium of interest, and noninvasive measurement where the monitoring system observes the … A variety of techniques are available enabling both invasive measurement, where the monitoring device is installed in the medium of interest, and noninvasive measurement where the monitoring system observes the medium of interest remotely. In this article we review the general techniques available, as well as specific instruments for particular applications. The issues of measurement criteria including accuracy, thermal disturbance and calibration are described. Based on the relative merits of different techniques, a guide for their selection is provided.
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Diffuse reflectance measurements by infrared Fourier transform spectrometry

1978-11-01
Michael P. Fuller , Peter R. Griffiths
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTDiffuse reflectance measurements by infrared Fourier transform spectrometryMichael P. Fuller and Peter R. GriffithsCite this: Anal. Chem. 1978, 50, 13, 1906–1910Publication Date (Print):November 1, 1978Publication History Published … ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTDiffuse reflectance measurements by infrared Fourier transform spectrometryMichael P. Fuller and Peter R. GriffithsCite this: Anal. Chem. 1978, 50, 13, 1906–1910Publication Date (Print):November 1, 1978Publication History Published online1 May 2002Published inissue 1 November 1978https://pubs.acs.org/doi/10.1021/ac50035a045https://doi.org/10.1021/ac50035a045research-articleACS PublicationsRequest reuse permissionsArticle Views4286Altmetric-Citations511LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InRedditEmail Other access optionsGet e-Alertsclose Get e-Alerts

Radiometric rectification: Toward a common radiometric response among multidate, multisensor images

1991-01-01
F. G. HALL , D. E. STREBEL , Jaime Nickeson +1 more

The Multiband Imaging Photometer for <i>Spitzer</i> (MIPS)

2004-09-01
G. H. Rieke , Erick T. Young , C. W. Engelbracht +7 more
The Multiband Imaging Photometer for Spitzer (MIPS) provides long-wavelength capability for the mission in imaging bands at 24, 70, and 160 μm and measurements of spectral energy distributions between 52 … The Multiband Imaging Photometer for Spitzer (MIPS) provides long-wavelength capability for the mission in imaging bands at 24, 70, and 160 μm and measurements of spectral energy distributions between 52 and 100 μm at a spectral resolution of about 7%. By using true detector arrays in each band, it provides both critical sampling of the Spitzer point-spread function and relatively large imaging fields of view, allowing for substantial advances in sensitivity, angular resolution, and efficiency of areal coverage compared with previous space far-infrared capabilities. The 24 μm array has excellent photometric properties, and measurements with rms relative errors of about 1% can be obtained. The two longer-wavelength arrays use detectors with poor photometric stability, but a system of onboard stimulators used for relative calibration, combined with a unique data pipeline, produce good photometry with rms relative errors of less than 10%.
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The analysis of apparent optical depth profiles for interstellar absorption lines

1991-09-01
Blair D. Savage , Kenneth R. Sembach
view Abstract Citations (633) References (21) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS The Analysis of Apparent Optical Depth Profiles for Interstellar Absorption Lines Savage, Blair D. … view Abstract Citations (633) References (21) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS The Analysis of Apparent Optical Depth Profiles for Interstellar Absorption Lines Savage, Blair D. ; Sembach, Kenneth R. Abstract Attention is given to the apparent optical depth method, a procedure for analyzing interstellar absorption lines. Observed absorption-line profiles are converted into profiles of apparent optical depth, and apparent column density per unit velocity. By comparing the latter for a given interstellar species having two or more absorption lines which differ in the product, the presence or absence of unresolved saturated structure in the profiles can be directly inferred. The method is illustrated using absorption-line data from the IUE satellite for the highly ionized gas toward HD 64760. Additional illustrations and a study of the method's accuracy are provided through a series of numerical simulations of multicomponent interstellar absorption situations. The method is compared to the standard growth curve method for deriving interstellar column densities. The principal value of the apparent optical depth method is that the absorption-line data are directly converted into a form that provides for direct scientific interpretations of the physical conditions in the interstellar absorbing medium as a function of velocity. Publication: The Astrophysical Journal Pub Date: September 1991 DOI: 10.1086/170498 Bibcode: 1991ApJ...379..245S Keywords: Absorption Spectra; Interstellar Extinction; Interstellar Matter; Line Spectra; Optical Thickness; Ultraviolet Spectra; Computerized Simulation; Error Analysis; Iue; Spectrum Analysis; Astrophysics; INTERSTELLAR: MATTER; LINE PROFILES; ULTRAVIOLET: SPECTRA full text sources ADS | data products SIMBAD (1) MAST (1) INES (1)

Radiometric scene normalization using pseudoinvariant features

1988-10-01
John R. Schott , Carl Salvaggio , William J. Volchok

The POLDER mission: instrument characteristics and scientific objectives

1994-05-01
Pierre Deschamps , François‐Marie Bréon , M. Leroy +4 more
This paper introduces the new Polarization and Directionality of the Earth's Reflectances (POLDER) instrument. The spaceborne POLDER sensor, which is selected to fly aboard the Japanese ADEOS satellite scheduled for … This paper introduces the new Polarization and Directionality of the Earth's Reflectances (POLDER) instrument. The spaceborne POLDER sensor, which is selected to fly aboard the Japanese ADEOS satellite scheduled for launch in early 1996, has nearly completed phase C of its development at the Centre National d'Etudes Spatiales, the French space agency. To prepare for the 1996 space mission, airborne prototypes are being tested and evaluated in the framework of various measurement campaigns. The POLDER sensor is designed to collect global observations of polarized and directional solar radiation reflected by the Earth-atmosphere system for climate and global change studies. Aboard the ADEOS platform, the POLDER mission will provide near-daily coverage of the Earth at 6/spl times/7 km/sup 2/ resolution. The POLDER system will offer unprecedented opportunities to observe biophysical parameters over the oceans and land surfaces. The sensor's unique features, when compared to current and planned spaceborne instruments, include its ability to: 1) measure polarized reflectance in the visible and near-infrared spectral regions; 2) observe Earth target reflectance from 12 directions during a single satellite pass; and 3) operate in two dynamic modes in order to achieve both high signal to noise ratio and wide dynamic range. Six of POLDER's eight channels are optimized for observing atmospheric aerosols, clouds, ocean color, and land surfaces. The other two are centered on the H/sub 2/O and O/sub 2/ absorption bands for retrieving atmospheric water vapor amount and cloud top altitude, respectively. POLDER data will be subject to the high calibration standards defined by the POLDER mission team, with absolute calibration accuracies of 2% for the shorter wavelength channels (/spl lambda//spl les/565 nm) and 3% for the longer wavelengths. A 1% accuracy is the goal for the intercalibration between the spectral channels. The POLDER instrument aboard ADEOS will contribute significantly to climate-related research on aerosol cycling, cloud-radiation interactions, the Earth radiation budget, ocean primary productivity, and continental biosphere dynamics. POLDER mission's scientific objectives will be to: 1) map atmospheric aerosols, including their sources and transport, and study their influence on the Earth radiation budget; 2) assess cloud properties, namely their height, phase and type; 3) estimate total integrated water vapor amount; 4) improve Earth radiation budget estimates; 5) estimate chlorophyll-like pigment content in the ocean surface layer and its role in the carbon cycle; and 6) characterize land surface properties and vegetation cover.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Optical Properties of the Atmosphere

1979-04-01
Linda J. Cox
"Optical Properties of the Atmosphere." Optica Acta: International Journal of Optics, 26(4), pp. 420–421 "Optical Properties of the Atmosphere." Optica Acta: International Journal of Optics, 26(4), pp. 420–421

Temperature measurement with a sonic anemometer and its application to heat and moisture fluxes

1983-05-01
P. Schotanus , F. T. M. Nieuwstadt , H.A.R. de Bruin

The sun’s total and spectral irradiance for solar energy applications and solar radiation models

2003-11-07
Christian A. Gueymard

Bidirectional reflectance spectroscopy: 1. Theory

1981-04-10
Bruce Hapke
An approximate analytic solution to the radiative transfer equation describing the scattering of light from particulate surfaces is derived. Multiple scattering and mutual shadowing are taken into account. Analytic expressions … An approximate analytic solution to the radiative transfer equation describing the scattering of light from particulate surfaces is derived. Multiple scattering and mutual shadowing are taken into account. Analytic expressions for the following quantities are found: bidirectional reflectance, radiance factor, radiance coefficient, normal, hemispherical, Bond, and physical albedos, integral phase function, phase integral, and limb‐darkening profile. Scattering functions for mixtures can be calculated, as well as corrections for comparing experimental laboratory transmission or reflection spectra with observational planetary spectra. An expression for the scattering efficiency of an irregular particle large compared with the wavelength is derived. For closely spaced, nonopaque particles this efficiency is approximated by (1 + α D e ) −l , where α is the true absorption coefficient and D e is an effective particle diameter of the order of twice the mean particle size. For monomineralic surfaces it is shown that α = ( 1 − w )/ w D e , where w is the single‐scattering albedo and can be determined from reflectance measurements of a powder, so that α may be calculated from reflectance. This theory should be useful for interpretations of reflectance spectroscopy of laboratory surfaces and photometry of solar system objects. From photometric observations of a body the following may be estimated: average single‐scattering albedo, average particle phase function, average macroscopic slope, and porosity.
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The importance of atmospheric differential refraction in spectrophotometry

1982-08-01
A. V. Filippenko
The effects of atmospheric differential refraction on astronomical measurements are much more important than is generally assumed. In particular, it is shown that relative line and continuum intensities in spectrophotometric … The effects of atmospheric differential refraction on astronomical measurements are much more important than is generally assumed. In particular, it is shown that relative line and continuum intensities in spectrophotometric work may be erroneous if this phenomenon is neglected. To help observers minimize these errors, the relation between object position and optimal slit or aperture orientation is derived, and practical tables and graphs are presented for use at the telescope.
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Retrieval of atmospheric temperature and composition from remote measurements of thermal radiation

1976-11-01
C. D. Rodgers
This paper reviews the methods which may be used to estimate the state of the atmosphere, i.e., the distribution of temperature and composition, from measurements of emitted thermal radiation such … This paper reviews the methods which may be used to estimate the state of the atmosphere, i.e., the distribution of temperature and composition, from measurements of emitted thermal radiation such as are made by remote sounding instruments on satellites. The principles of estimation theory are applied to a linear version of the problem, and it is shown that many of the apparently different methods to be found in the literature are particular cases of the same general method. As an aid to understanding, the optimum linear solution is described in terms of the geometry of n dimensions, with n = 3 for illustration. In generalizing the approach to the nonlinear problem there are two stages: (1) finding any member of the infinite family of possible solutions, which may be done by any convenient iterative method, and (2) finding the optimum solution by satisfying appropriate constraints.

Atmospheric correction of MODIS data in the visible to middle infrared: first results

2002-11-01
Éric Vermote , Nazmi Saleous , Christopher O. Justice

The Photometric Performance and Calibration of WFPC2

1995-11-01
Jon A. Holtzman , Christopher J. Burrows , Stefano Casertano +4 more
We discuss the photometric performance and calibration of the Wide Field Planetary Camera 2 (WFPC2) on the Hubble Space Telesopce (HST). The stability and accuracy of WFPC2 photometric measurements is … We discuss the photometric performance and calibration of the Wide Field Planetary Camera 2 (WFPC2) on the Hubble Space Telesopce (HST). The stability and accuracy of WFPC2 photometric measurements is discussed, with particular attention given to charge transfer efficiency (CTE) effects, contamination effects in the ultraviolet (UV), and flat field accuracy and normalization. Observational data are presented from both WFPC2 observations and ground observations using a system similar to that flown. WFPC2 photometric systems are defined both for the ground and flight systems. Transformations between these systems and the Landolt UBVRI system are presented. These transformations are sensitive to details in the spectra being transformed, and these sensitivities are quantified and discussed. On-orbit observations are used to revise the prelaunch estimates of response curves to best match synthetic photometry results with observations, and the accuracy of the resulting synthetic photometry is discussed. Synthetic photometry is used to determine zeropoints and transformations for all of the fight filters, and also to derive interstellar extinction values for the WFPC2 system. Using stellar interior and atmosphere models, isochrones in the WFPC2 system are calculated and compared with several observations.
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Optical properties of the metals Al, Co, Cu, Au, Fe, Pb, Ni, Pd, Pt, Ag, Ti, and W in the infrared and far infrared

1983-04-01
Mark A. Ordal , Larry L. Long , R. J. Bell +4 more
Infrared optical constants collected from the literature are tabulated. The data for the noble metals and Al, Pb, and W can be reasonably fit using the Drude model. It is … Infrared optical constants collected from the literature are tabulated. The data for the noble metals and Al, Pb, and W can be reasonably fit using the Drude model. It is shown that -epsilon1(omega) = epsilon2(omega) approximately omega(2)(p)/(2omega(2)(tau)) at the damping frequency omega = omega(tau). Also -epsilon1(omega(tau)) approximately - (1/2) epsilon1(0), where the plasma frequency is omega(p).

Multi-angle Imaging SpectroRadiometer (MISR) instrument description and experiment overview

1998-07-01
David J. Diner , J.C. Beckert , T. H. Reilly +7 more
The Multi-angle Imaging SpectroRadiometer (MISR) instrument is scheduled for launch aboard the first of the Earth Observing System (EOS) spacecraft, EOS-AM1. MISR will provide global, radiometrically calibrated, georectified, and spatially … The Multi-angle Imaging SpectroRadiometer (MISR) instrument is scheduled for launch aboard the first of the Earth Observing System (EOS) spacecraft, EOS-AM1. MISR will provide global, radiometrically calibrated, georectified, and spatially coregistered imagery at nine discrete viewing angles and four visible/near-infrared spectral bands. Algorithms specifically developed to capitalize on this measurement strategy will be used to retrieve geophysical products for studies of clouds, aerosols, and surface radiation. This paper provides an overview of the as-built instrument characteristics and the application of MISR to remote sensing of the Earth.

Atmospheric correction of visible to middle‐infrared EOS‐MODIS data over land surfaces: Background, operational algorithm and validation

1997-07-01
Éric Vermote , Nazmi Saleous , Chris Justice +5 more
The NASA moderate resolution imaging spectroradiometer (MODIS) instrument will provide a global and improved source of information for the study of land surfaces with a spatial resolution of up to … The NASA moderate resolution imaging spectroradiometer (MODIS) instrument will provide a global and improved source of information for the study of land surfaces with a spatial resolution of up to 250 m. Prior to the derivation of various biophysical parameters based on surface reflectances, the top of the atmosphere signals need to be radiometrically calibrated and corrected for atmospheric effects. The present paper describes in detail the state of the art techniques that will be used for atmospheric correction of MODIS bands 1 through 7, centered at 648, 858, 470, 555, 1240, 1640, and 2130 nm, respectively. Previous operational correction schemes have assumed a standard atmosphere with zero or constant aerosol loading and a uniform, Lambertian surface. The MODIS operational atmospheric correction algorithm, reported here, uses aerosol and water vapor information derived from the MODIS data, corrects for adjacency effects and takes into account the directional properties of the observed surface. This paper also describes the operational implementation of these techniques and its optimization. The techniques are applied to remote sensing data from the Landsat Thematic Mapper (TM), the NOAA advanced very high resolution radiometer (AVHRR), and the MODIS airborne simulator (MAS) and validated against ground‐based measurements from the Aerosol Robotic Network (AERONET).
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Characterization and error analysis of profiles retrieved from remote sounding measurements

1990-04-20
Clive D. Rodgers
The characterization and error analysis of profiles retrieved from remote measurements present conceptual problems, particularly concerning interlevel correlations between errors, the smoothing effect of remote sounding and the contribution of … The characterization and error analysis of profiles retrieved from remote measurements present conceptual problems, particularly concerning interlevel correlations between errors, the smoothing effect of remote sounding and the contribution of a priori information to profile. A formal analysis for profile retrieval is developed which is independent of the nature of the retrieval method, provided that the measurement process can be characterized adequately. The relationship between the retrieved and true profiles is expressed in terms of a smoothing function which can be straightforwardly calculated. The retrieval error separates naturally into three components, (1) random error due to measurement noise, (2) systematic error due to uncertain model parameters and inverse model bias, and (3) null‐space error due to the inherent finite vertical resolution of the observing system. A recipe is given for evaluating each of the components in any particular case. Most of the error terms appear as covariance matrices, rather than simple error variances. These matrices can be interpreted in terms of “error patterns”, which are statistically independent contributions to the total error. They are the multidimensional equivalent of “error bars”. An approach is described which clarifies the relation of a priori data to the retrieved profile, and identifies a priori in cases where it is not an explicit part of the retrieval.

Revised landsat-5 tm radiometric calibration procedures and postcalibration dynamic ranges

2003-11-01
Gyanesh Chander , Brian L. Markham
Effective May 5, 2003, Landsat-5 (L5) Thematic Mapper (TM) data processed and distributed by the U.S. Geological Survey (USGS) Earth Resources Observation System (EROS) Data Center (EDC) will be radiometrically … Effective May 5, 2003, Landsat-5 (L5) Thematic Mapper (TM) data processed and distributed by the U.S. Geological Survey (USGS) Earth Resources Observation System (EROS) Data Center (EDC) will be radiometrically calibrated using a new procedure and revised calibration parameters. This change will improve absolute calibration accuracy, consistency over time, and consistency with Landsat-7 (L7) Enhanced Thematic Mapper Plus (ETM+) data. Users will need to use new parameters to convert the calibrated data products to radiance. The new procedure for the reflective bands (1-5,7) is based on a lifetime radiometric calibration curve for the instrument derived from the instrument's internal calibrator, cross-calibration with the ETM+, and vicarious measurements. The thermal band will continue to be calibrated using the internal calibrator. Further updates to improve the relative detector-to-detector calibration and thermal band calibration are being investigated, as is the calibration of the Landsat-4 (L4) TM.
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Summary of current radiometric calibration coefficients for Landsat MSS, TM, ETM+, and EO-1 ALI sensors

2009-02-27
Gyanesh Chander , Brian L. Markham , Dennis Helder
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Geo-atmospheric processing of airborne imaging spectrometry data. Part 2: Atmospheric/topographic correction

2002-01-01
Rudolf Richter , Daniel Schläpfer
A method for the radiometric correction of wide field-of-view airborne imagery has been developed that accounts for the angular dependence of the path radiance and atmospheric transmittance functions to remove … A method for the radiometric correction of wide field-of-view airborne imagery has been developed that accounts for the angular dependence of the path radiance and atmospheric transmittance functions to remove atmospheric and topographic effects. The first part of processing is the parametric geocoding of the scene to obtain a geocoded, orthorectified image and the view geometry (scan and azimuth angles) for each pixel as described in part 1 of this jointly submitted paper. The second part of the processing performs the combined atmospheric/ topographic correction. It uses a database of look-up tables of the atmospheric correction functions (path radiance, atmospheric transmittance, direct and diffuse solar flux) calculated with a radiative transfer code. Additionally, the terrain shape obtained from a digital elevation model is taken into account. The issues of the database size and accuracy requirements are critically discussed. The method supports all common types of imaging airborne optical instruments: panchromatic, multispectral and hyperspectral, including fore/aft tilt sensors covering the wavelength range 0.35-2.55 w m and 8-14 w m. The processor is designed and optimized for imaging spectrometer data. Examples of processing of hyperspectral imagery in flat and rugged terrain are presented. A comparison of ground reflectance measurements with surface reflectance spectra derived from airborne imagery demonstrates that an accuracy of 1-3% reflectance units can be achieved.

The Refractive Index of Air

1966-04-01
Bengt Edlén
Present knowledge of the refractive index of air is reviewed. Regarding the absolute values there are as yet no definite indications that the standard adopted in 1953 on the basis … Present knowledge of the refractive index of air is reviewed. Regarding the absolute values there are as yet no definite indications that the standard adopted in 1953 on the basis of Barrell and Sears' measurements should be changed, but new experiments aiming at reducing the present uncertainty of about ± 5 × 10-8 would be desirable.

Landsat-8: Science and product vision for terrestrial global change research

2014-03-04
David P. Roy , Michael A. Wulder , Thomas R. Loveland +7 more
Landsat 8, a NASA and USGS collaboration, acquires global moderate-resolution measurements of the Earth's terrestrial and polar regions in the visible, near-infrared, short wave, and thermal infrared. Landsat 8 extends … Landsat 8, a NASA and USGS collaboration, acquires global moderate-resolution measurements of the Earth's terrestrial and polar regions in the visible, near-infrared, short wave, and thermal infrared. Landsat 8 extends the remarkable 40 year Landsat record and has enhanced capabilities including new spectral bands in the blue and cirrus cloud-detection portion of the spectrum, two thermal bands, improved sensor signal-to-noise performance and associated improvements in radiometric resolution, and an improved duty cycle that allows collection of a significantly greater number of images per day. This paper introduces the current (2012–2017) Landsat Science Team's efforts to establish an initial understanding of Landsat 8 capabilities and the steps ahead in support of priorities identified by the team. Preliminary evaluation of Landsat 8 capabilities and identification of new science and applications opportunities are described with respect to calibration and radiometric characterization; surface reflectance; surface albedo; surface temperature, evapotranspiration and drought; agriculture; land cover, condition, disturbance and change; fresh and coastal water; and snow and ice. Insights into the development of derived 'higher-level' Landsat products are provided in recognition of the growing need for consistently processed, moderate spatial resolution, large area, long-term terrestrial data records for resource management and for climate and global change studies. The paper concludes with future prospects, emphasizing the opportunities for land imaging constellations by combining Landsat data with data collected from other international sensing systems, and consideration of successor Landsat mission requirements.

Calculation of absorption corrections for camera and diffractometer data

1965-06-01
P. Coppens , Leslie Leiserowitz , D. Rabinovich
Since, on applying the limits the first term in the righthand side of (C-5) vanishes, we have k2pl l; Since, on applying the limits the first term in the righthand side of (C-5) vanishes, we have k2pl l;
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Prelaunch characteristics of the Moderate Resolution Imaging Spectroradiometer (MODIS) on EOS-AM1

1998-07-01
William L. Barnes , Thomas S. Pagano , V. V. Salomonson
The Moderate Resolution Imaging Spectroradiometer (MODIS), with 36 bands and 0.25-, 0.5-, and 1.0-km geometric instantaneous-fields-of-view (GIFOVs) at nadir, has completed system level testing and has been integrated onto the … The Moderate Resolution Imaging Spectroradiometer (MODIS), with 36 bands and 0.25-, 0.5-, and 1.0-km geometric instantaneous-fields-of-view (GIFOVs) at nadir, has completed system level testing and has been integrated onto the Earth Observing System (EOS)-AM1 spacecraft, which is slated for launch in 1998. Raytheon Santa Barbara Remote Sensing (SBRS), Goleta, CA, the MODIS developer, has performed extensive characterization and calibration measurements that have demonstrated a system that meets or exceeds most of NASA's demanding requirements. Based on this demonstrated capability, the MODIS Science Team, an international group of 28 land, ocean, atmosphere, and calibration remote-sensing scientists, has commenced delivery of algorithms that will routinely calculate 42 MODIS standard data products postlaunch. These products range from atmospheric aerosols, snow cover, and land and water surface temperature to leaf area index, ocean chlorophyll concentration, and sea ice extent, to name just a few. A description of the Science Team, including members' research interests and descriptions of their MODIS algorithms, can be found at the MODIS homepage (http://ltpwww.gsfc.nasa.gov/MODIS/MODIS.html). The MODIS system level testing included sufficient measurements in both ambient and thermal-vacuum environments to both demonstrate specification compliance and enable postlaunch implementation of radiometric calibration algorithms. The latter will include calculations to account for changes in response versus scan angle, response versus temperature, and response linearity. The system level tests also included performance verification of the onboard calibration systems, including the solar diffuser stability monitor (SDSM), the blackbody (BB), and the spectral radiometric calibration assembly (SRCA), which will enahle monitoring of MODIS performance postlaunch. Descriptions of these subsystems are also on the MODIS homepage.
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Reflectance quantities in optical remote sensing—definitions and case studies

2006-06-07
Gabriela Schaepman‐Strub , Michael E. Schaepman , T. H. Painter +2 more

Fourier transform infrared spectrometry

1986-01-01
D. E. Honigs

The relationship between infrared, optical, and ultraviolet extinction

1989-10-01
Jason A. Cardelli , Geoffrey C. Clayton , John S. Mathis
view Abstract Citations (9701) References (43) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS The Relationship between Infrared, Optical, and Ultraviolet Extinction Cardelli, Jason A. ; Clayton, Geoffrey … view Abstract Citations (9701) References (43) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS The Relationship between Infrared, Optical, and Ultraviolet Extinction Cardelli, Jason A. ; Clayton, Geoffrey C. ; Mathis, John S. Abstract The parameterized extinction data of Fitzpatrick and Massa (1986, 1988) for the ultraviolet and various sources for the optical and near-infrared are used to derive a meaningful average extinction law over the 3.5 micron to 0.125 wavelength range which is applicable to both diffuse and dense regions of the interstellar medium. The law depends on only one parameter R(V) = A(V)/E(B-V). An analytic formula is given for the mean extinction law which can be used to calculate color excesses or to deredden observations. The validity of the law over a large wavelength interval suggests that the processes which modify the sizes and compositions of grains are stochastic in nature and very efficient. Publication: The Astrophysical Journal Pub Date: October 1989 DOI: 10.1086/167900 Bibcode: 1989ApJ...345..245C Keywords: Infrared Spectra; Interstellar Extinction; Ultraviolet Spectra; Visible Spectrum; Computational Astrophysics; Interstellar Matter; Iue; Astrophysics; INTERSTELLAR: MATTER; ULTRAVIOLET: SPECTRA full text sources ADS | data products SIMBAD (38) MAST (2)

An algorithm for the retrieval of albedo from space using semiempirical BRDF models

2000-03-01
Wolfgang Lucht , Crystal Schaaf , Alan H. Strahler
Spectral albedo may be derived from atmospherically corrected, cloud-cleared multiangular reflectance observations through the inversion of a bidirectional reflectance distribution function (BRDF) model and angular integration. This paper outlines an … Spectral albedo may be derived from atmospherically corrected, cloud-cleared multiangular reflectance observations through the inversion of a bidirectional reflectance distribution function (BRDF) model and angular integration. This paper outlines an algorithm suitable for this task that makes use of kernel-based BRDF models. Intrinsic land surface albedos are derived, which may be used to derive actual albedo by taking into account the prevailing distribution of diffuse skylight. Spectral-to-broadband conversion is achieved using band-dependent weighting factors. The validation of a suitable BRDF model, the semiempirical Ross-Li (reciprocal RossThick-LiSparse) model and its performance under conditions of sparse angular sampling and noisy reflectances are discussed, showing that the retrievals obtained are generally reliable. The solar-zenith angle dependence of albedo may be parameterized by a simple polynomial that makes it unnecessary for the user to be familiar with the underlying BRDF model. The algorithm given is that used for the production of a BRDF/albedo standard data product from NASA's EOS-MODIS sensor, for which an at-launch status is provided. Finally, the algorithm is demonstrated on combined AVHRR and GOES observations acquired over New England, from which solar zenith angle-dependent albedo maps with a nominal spatial resolution of 1 km are derived in the visible band. The algorithm presented may be employed to derive albedo from space-based multiangular measurements and also serves as a guide for the use of the MODIS BRDF/albedo product.

Astronomical Measurements in the Infrared

1966-09-01
Harold L. Johnson

SMAC: a simplified method for the atmospheric correction of satellite measurements in the solar spectrum

1994-01-01
Hafızur Rahman , Gérard Dedieu
Abstract This paper describes a computationally fast and accurate technique for the atmospheric correction of satellite measurements in the solar spectrum. The main advantage of the method is that it … Abstract This paper describes a computationally fast and accurate technique for the atmospheric correction of satellite measurements in the solar spectrum. The main advantage of the method is that it is several hundred times faster than more detailed radiative transfer models like 5S and that it does not require precalculated look-up tables. The method is especially useful for correcting the huge amounts of data acquired by large-field-of-view high-repetitivity sensors, like the ones on board polar orbiting and geostationary meteorological satellites. The technique is based on a set of equations with coefficients which depend on the spectral band of the sensor. Semi-empirical formulations are used to describe the different interactions (absorption, scattering, etc.) of solar radiation with atmospheric constituents during its traverse through the atmosphere. Sensor specific coefficients of each equation are determined using a best fit technique against the computations of the 5S code (Simulation of Satellite Signal in the Solar Spectrum, Tanré et al. 1990). Other radiative transfer models could be used. Once coefficients for a specific spectral band are determined, the inputs of the model are vertically integrated gaseous contents, aerosol optical depth at 550 nm, geometric conditions and reflectance at the top of the atmosphere (TOA). TOA reflectances were calculated using our method and then compared to the TOA reflectances calculated by 5S for a wide range of gaseous and aerosol contents, illumination and observation conditions for various sensor spectral bands. In the case of NOAA-9 AVHRR visible data the maximum relative error is 2·35 per cent (i.e. 0·01 for a reflectance value of 0·4) and the corresponding rmse is 0·0018. For NOAA-9 AVHRR near-infrared, Meteosat-1 visible, Landsat-5 TM band 1 and Landsat-5 TM band 4 the maximum relative errors are 3·11, 4·0, 1·65 and 2·37per cent respectively. The corresponding values of the rmse are 0·0022, 0·0015, 0·0017 and 0·0012. The method can be used both in the direct and in the inverse mode, i.e., to compute TOA reflectance knowing the surface reflectance (e.g., for fast sensitivity studies), or conversely to retrieve surface reflectance from the TOA reflectance. It can easily be implemented in operational data preprocessing computer code, since only band specific coefficients need to be updated when new sensors are flown, while the routines remain the same.

Image-Based Atmospheric Corrections - Revisited and Improved

1996-01-01
Pat S. Chavez
A major benefit of multitemporal, remotely sensed images is their applicability to change detection over time. Because of concerns about global and environmental change, these data are becoming increasingly more … A major benefit of multitemporal, remotely sensed images is their applicability to change detection over time. Because of concerns about global and environmental change, these data are becoming increasingly more important. However, to maximize the usefulness of the data from a multitemporal point of view, an easy-to-use, cost-effective, and accurate radiometric calibration and correction procedure is needed. The atmosphere effects the radiance received at the satellite by scattering, absorbing, and refracting light; corrections for these effects, as well as for sensor gains and offsets, solar irradiance, and solar zenith angles, must be included in radiometric correction procedures that are used to convert satellite-recorded digital counts to ground reflectances. To generate acceptable radiometric correction results, a model is required that typically uses in-situ atmospheric measurements and radiative transfer code (RTC) to correct for atmospheric effects. The main disadvantage of this type of correction procedure is that it requires in-situ field measurements during each satellite overflight. This is unacceptable for many applications and is often impossible, as when using historical data or when working in very remote locations. The optimum radiometric correction procedure is one based solely on the digital image and requiring no in-situ field measurements during the satellite overflight. The darkobject subtraction (DOS) method, a strictly image-based technique, is an attempt to achieve this ideal procedure. However, the accuracy is not acceptable for many applications, mostly because it corrects only for the additive scattering effect and not for the multiplicative transmittance effect. This paper presents an entirely image-based procedure that expands on the ~10s model by including a simple multiplicative correction for the effect of atmospheric transmittance. Two straightforward methods to derive the multiplicative transmittance-correction coefficient are presented. The COSITZ) or COST method uses the cosine of the solar zenith angle, which, to a first order, is a good approximation of the atmospheric transmittance for the dates und sites used in this study. The default TAUS method uses the average of the transmittance values computed by using in-situ atmospheric field measurements made during seven different satellite overflights. Published and unpublished data made available for this study by Moran et al. (1992) are used, and my model results are compared with their results. The corrections generated by the entirely image-based COST model are as accurate as those generated by the models that used in-situ atmospheric field measurements and RTC software.

<i>Planck</i>2013 results. VII. HFI time response and beams

2014-01-06
P. A. R. Ade , N. Aghanim , C. Armitage-Caplan +7 more
This paper characterizes the effective beams,the effective beam window functions and the associated errors for the Planck HFI detectors. The effective beam is the angular response including the effect of … This paper characterizes the effective beams,the effective beam window functions and the associated errors for the Planck HFI detectors. The effective beam is the angular response including the effect of the optics,detectors,data processing and the scan strategy. The window function is the representation of this beam in the harmonic domain which is required to recover an unbiased measurement of the CMB angular power spectrum. The HFI is a scanning instrument and its effective beams are the convolution of: (a) the optical response of the telescope and feeds;(b)the processing of the time-ordered data and deconvolution of the bolometric and electronic time response; and (c) the merging of several surveys to produce maps. The time response functions are measured using observations of Jupiter and Saturn and by minimizing survey difference residuals. The scanning beam is the post-deconvolution angular response of the instrument, and is characterized with observations of Mars. The main beam solid angles are determined to better than 0.5% at each HFI frequency band. Observations of Jupiter and Saturn limit near sidelobes (within 5deg) to about 0.1% of the total solid angle. Time response residuals remain as long tails in the scanning beams, but contribute less than 0.1% of the total. The bias and uncertainty in the beam products are estimated using ensembles of simulated planet observations that include the impact of instrumental noise and known systematic effects.The correlation structure of these ensembles is well-described by five error eigenmodes that are sub-dominant to sample variance and instrumental noise in the harmonic domain. A suite of consistency tests provide confidence that the error model represents a sufficient description of the data. The total error in the effective beam window functions is below 1% at 100GHz up to ell~1500$,and below 0.5% at 143 and 217GHz up to ~2000.
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Eddy Covariance

2012-01-01
Georg Wohlfahrt , Katja Klumpp , Jean‐François Soussana

ASTROPHYSICAL QUANTITIES

1964-01-01

The Use and Potential of Far-Infrared Remote Sensing in deriving Surface Longwave Downward Radiation under clear-sky conditions

2025-06-24
Yihan Du , Tianxing Wang , Dahui Li +3 more | Bulletin of the American Meteorological Society
Abstract Surface Longwave Downward Radiation (LWDR) is an essential parameter in Earth's radiation balance and climate change studies. To date, almost all existing space-based LWDR studies mainly focus on the … Abstract Surface Longwave Downward Radiation (LWDR) is an essential parameter in Earth's radiation balance and climate change studies. To date, almost all existing space-based LWDR studies mainly focus on the traditional thermal infrared (TIR) spectra of 4-15 μm. The far-infrared (FIR) spectrum (&gt;15 μm), with its high sensitivity to temperature and water vapor, has the potential to greatly improve the derivation accuracy of LWDR, which is closely related to the above variables. This study proposes a novel attempt to estimate clear-sky LWDR by integrating the traditional TIR bands and newly selected FIR bands. Through comprehensive simulations and analyses, we identify that the FIR bands can serve as an essential complement to existing TIR-based methods, thereby significantly improving the accuracy of LWDR estimation, yielding a 16% overall accuracy improvement. This substantial potential for enhanced accuracy is particularly evident under conditions of low water vapor content or in polar atmospheres, where improvements exceed 23%. This research represents the first incorporation of FIR into longwave radiation estimation fields, highlighting a promising advancement in remote sensing techniques. The findings inspire further exploration of FIR's potential and lay the groundwork for a deeper understanding of LWDR and the complexities of Earth's radiation balance, ultimately aiding in more accurate assessments of climate change.

A scanning apparatus to detect the spectral directivity of optically-emissive materials

2025-06-24
Hengzhou Liu , Anthony Fiorito , David Sheffield +3 more | Applied Optics

JPSS-4 VIIRS Pre-Launch Calibration Performance and Assessment

2025-06-23
Amit Angal , David Moyer , Xiaoxiong Xiong +5 more | Remote Sensing
The Joint Polar Satellite System (JPSS) is a collaborative program between NASA and NOAA to provide scientific measurements from multiple polar-orbiting satellites. The development, testing, launch, and operation of the … The Joint Polar Satellite System (JPSS) is a collaborative program between NASA and NOAA to provide scientific measurements from multiple polar-orbiting satellites. The development, testing, launch, and operation of the satellites is jointly overseen by NASA and NOAA, with NASA responsible for developing and building instruments, spacecraft, ground systems, and launching into orbit. While three VIIRS instruments are currently on-orbit, spacecraft integration of the two VIIRS instruments planned for launch on the JPSS-3 and -4 spacecraft is ongoing. The latest build in the series, set to be launched on the JPSS-4 platform, recently completed its main ground calibration program at the vendor facility. This program covered a comprehensive series of performance metrics designed to ensure that the instrument can maintain its calibration successfully on-orbit. In this paper, we present the results from the radiometric calibration process, which includes metrics such as dynamic range, signal-to-noise ratio, noise equivalent differential temperature, polarization sensitivity, scattered light response, relative spectral response, response versus scan angle, and crosstalk. All key metrics have met or exceeded their design requirements, with some minor exceptions. Also included are comparisons with previous VIIRS instruments, as well as a description of their expected performance once on-orbit.

Minimizing angle of incidence error on intensity ratio phosphor thermometry

2025-06-20
Weilun Cheng , Yingzheng Liu , Di Peng +1 more | Measurement Science and Technology
Abstract Intensity ratio-based phosphor thermometry is a promising technique for instantaneous temperature measurement of fast-moving objects. However, its accuracy is limited by the blueshift effects of interference filters induced by … Abstract Intensity ratio-based phosphor thermometry is a promising technique for instantaneous temperature measurement of fast-moving objects. However, its accuracy is limited by the blueshift effects of interference filters induced by angle of incidence (AOI) variations. This is especially problematic for phosphors with significant temperature-dependent emission band shifts. To address this issue, we propose the following two-step method: Firstly, a simulation procedure is developed to evaluate measurement errors induced by AOI variations under different filter sets using the BaMgAl10O17:Eu2+ (BAM:Eu) phosphor. Simulation results are carefully analyzed, and a filter set is selected which results in low AOI errors and high temperature sensitivity. Secondly, an experimental temperature-AOI calibration method is developed by fitting the intensity ratio distribution under different AOIs and temperatures using a bivariate quadratic function. Finally, the intensity ratio-based phosphor thermometry method with the selected filter set and the temperature-AOI calibration is validated via surface temperature measurements on a heated disk. AOI-induced errors up to 25 K and 12 K are effectively removed under stationary and rotating conditions, respectively.&amp;#xD;

Development of a calibration system for process safety applications of passive infrared gas imaging detectors

2025-06-19
Po Ma , Bing Yang , C. Chao +7 more | Measurement

Demonstration of low-order wavefront sensing and control system of Roman coronagraph instrument in thermal vacuum testing environment

2025-06-17
Byoung-Joon Seo , Nanaz Fathpour , David Arndt +4 more | Journal of Astronomical Telescopes Instruments and Systems

Quality assessment of Airborne Image Spectrometry Data for the AVIRIS-4

2025-06-16
Laurent Valentin Jospin , J. Lahaye , Jan Škaloud | ˜The œinternational archives of the photogrammetry, remote sensing and spatial information sciences/International archives of the photogrammetry, remote sensing and spatial information sciences
Abstract. The AVIRIS-4 is a state of the art imaging spectrometer developed by NASA-JPL for the consortium of Swiss universities ARES. Measurement campaigns using this instrument started in 2024. According … Abstract. The AVIRIS-4 is a state of the art imaging spectrometer developed by NASA-JPL for the consortium of Swiss universities ARES. Measurement campaigns using this instrument started in 2024. According to the agreement with NASA-JPL, all imagery produced by the AVIRIS-4 should be made available as open data. To support the efforts of the ARES consortium in improving the quality and interoperability of the produced research data, in line with the FAIR framework for open data, a new tool is proposed to label tie points on hyperspectral imagery and use them as quality control indicators of the georeferencing process. A case study on the first flight of the system acquired for the geometric calibration of AVIRIS-4 is presented. Based on the proposed quality indicators, errors in the measured trajectory data collected in flight were identified, indicating the need for a new calibration flight, further refinement of the proposed trajectory optimization framework and guiding the design of future missions.

Interior redox state effects on the stability of secondary atmospheres and observational manifestations: LP 791-18,d as a case study for outgassing rocky exoplanets

2025-06-16
L. Gkouvelis , F. J. Pozuelos , Thomas Drant +3 more | Astronomy and Astrophysics
Recent advances in space-based and ground-based facilities now allow the atmospheric characterization of a selected sample of rocky exoplanets. These atmospheres offer key insights into planetary formation and evolution, but … Recent advances in space-based and ground-based facilities now allow the atmospheric characterization of a selected sample of rocky exoplanets. These atmospheres offer key insights into planetary formation and evolution, but their interpretation requires models that couple atmospheric processes with both the planetary interior and the surrounding space environment. This work focuses on the Earth-size planet LP 791-18,d, which is estimated to receive continuous tidal heating due to the orbital configuration of the system; thus, it is expected to exhibit volcanic activity. Using a 1D radiative-convective model coupled with chemical kinetics and an outgassing scheme at the lower boundary, we simulated the planet’s atmospheric composition across a range of oxygen fugacities, surface pressures, and graphite activities. We estimated the mantle temperature of ≈1680 - 1880 K, balancing the competing contributions of interior tidal heating and convective cooling. Our results show that the atmospheric mean molecular weight gradient is controlled by oxygen fugacity rather than bulk metallicity. Furthermore, we used the atmospheric steady-state solutions produced from the interior redox state versus surface pressure parameter space, and explored their atmospheric stability. We find that stability is achieved only in highly oxidized scenarios, fO_2-IW≳ 2, while reduced interior states fall into the hydrodynamic escape regime with mass loss rates on the order of ≈ 10^5-10^8 We argue that scenarios with reduced interior states are likely to have exhausted their volatile budget during the planet's lifetime. Furthermore, we predict the atmospheric footprint of the planet's interior based on its oxidation state and assess its detectability using current or forthcoming tools to constrain the internal and atmospheric composition. We show that the degeneracy between bare rock surfaces and thick atmospheres can be resolved by using three photometric bands to construct a color–color diagram that accounts for potential effects from photochemical hazes and clouds. For JWST/MIRI, this discrimination is possible only in the case of highly oxidized atmospheres. The case of LP 791-18,d enables the investigation of secondary atmosphere formation through outgassing, with implications for similar rocky exoplanets. Our modeling approach connects interior and atmospheric processes, providing a basis for exploring volatile evolution and potential habitability.

The role of echosounder measurement in lidar point cloud calibration

2025-06-16
Ewa Anna Gasińska-Kołyszko | ˜The œinternational archives of the photogrammetry, remote sensing and spatial information sciences/International archives of the photogrammetry, remote sensing and spatial information sciences
Abstract. The calibration of the lidar point clouds over aquatic environments presents unique challenges compared to terrestrial calibration, primarily due to the refractive and reflective properties of water. This discrepancy … Abstract. The calibration of the lidar point clouds over aquatic environments presents unique challenges compared to terrestrial calibration, primarily due to the refractive and reflective properties of water. This discrepancy arises due to the fact that the majority of the calibrated area is situated in a water body. In instances where a point cloud contains water, alternative methods can be employed. These include the utilization of control points located on the beach or an echosounder with a depth greater than 1m.The area was subjected to thorough research in the vicinity of Lubiatowo, where a 1.5-kilometre coastal zone was identified, with a depth of approximately 10 meters. This survey was conducted using a lidar point cloud, created in 2018 by the Austrian company Airborne Hydro Mapping (A-M) for Polish company Apeks. The Riegl Vq880g scanner was utilized in the measurement process, which involved the registration of the seabed and the adjacent land near Lubiatowo. In the immediate vicinity, the seabed was subsequently measured using the echosounder Echotrac Cv100 (Odom) of the Polish Academy of Sciences in Gdańsk. All measurements were conducted under calm sea conditions, which minimized surface interference and improved data consistency.The received data were found to be in a 3D coordinate system UTM\\WGS84 ellipsoid, and appeared to be preprocessed lidar point cloud. Therefore, an investigation was made into the relationship to the echosounder measurement. It was determined that the transforms used programs such as Microstation Power Draft with Terrascan, Geokonwerter, and Microsoft Office Excel. Calibration of the lidar point cloud was primarily conducted at a depth greater than 1m, based on echosounder measurements. Initially, the adjustment lidar point cloud size was defined to enhance its accuracy. Following the calibration process, the lidar point cloud was matched to the echosounder. The point cloud’s correction magnitude (average) ranged from -1.14m. It is imperative to measure additional data using an echosounder during the registration of lidar data. This result underscores the necessity of integrating hydroacoustic measurements for accurate registration of lidar data in submerged environments, and reinforces the importance of methodical calibration in the development of reliable coastal and bathymetric models.

Empirical broadband polarimetric bidirectional reflectance distribution function measurement framework for application to remote sensing data

2025-06-14
Sultan S. Aldkeelalah , David Perry , Andrew J. Niklas +1 more | Optical Engineering

Dual-wavelength extreme ultraviolet camera (EUC) for the Chang’E-7 mission: Instrument development and calibration

2025-06-13
Lingping He , Fei He , Bo Chen +7 more | Science China Technological Sciences

Secondary electron emission current mapping for nanoscale thermometry

2025-06-13
William A. Hubbard , Matthew Mecklenburg , Ho Leung Chan +1 more | Nanotechnology
Abstract Secondary electron (SE) emission is temperature-dependent, and thus could form the basis of an electron microscopy-based thermometry technique with nanoscale spatial resolution. To explore this possibility, we measure the … Abstract Secondary electron (SE) emission is temperature-dependent, and thus could form the basis of an electron microscopy-based thermometry technique with nanoscale spatial resolution. To explore this possibility, we measure the SE emission from heated test structures using scanning transmission electron microscopy (STEM) electron beam-induced current (EBIC) imaging. The test structures consist of an electrode, which is made of platinum or amorphous carbon, and an encircling heater. Aluminum nanoparticles decorate the test structures and serve as local nanothermometers that we read-out with plasmon energy expansion themometry (PEET). Energizing the heaters, we measure the SE emission from the electrodes and nanothermometers. The SE emission from Pt, C, and Al is a simple, supralinear function of the PEET-calibrated temperature that is well-fit with a single free parameter. SEEBIC thermometry thus shows promise for being a widely applicable, TEM-based temperature mapping technique.

Comparative evaluation of NASA, ERA5, and observational data for accuracy and reliability

2025-06-12
Atilla Mutlu | Theoretical and Applied Climatology

Measurement of Coefficient of Thermal Expansion of Metallic Materials from 20 to 150 K by Speckle Interferometry

2025-06-12
Yong Shuai , Yongsheng Zhu , CuiPing Yu +3 more | International Journal of Thermophysics

WASP-121 b’s Transmission Spectrum Observed with JWST/NIRSpec G395H Reveals Thermal Dissociation and SiO in the Atmosphere

2025-06-02
Cyril Gapp , T. M. Evans , J. K. Barstow +7 more | The Astronomical Journal
Abstract WASP-121 b has been established as a benchmark ultrahot Jupiter, serving as a laboratory for the atmospheric chemistry and dynamics of strongly irradiated extrasolar gas giants. Here, we present … Abstract WASP-121 b has been established as a benchmark ultrahot Jupiter, serving as a laboratory for the atmospheric chemistry and dynamics of strongly irradiated extrasolar gas giants. Here, we present and analyze WASP-121 b's transmission spectrum observed with NIRSpec G395H on board the James Webb Space Telescope and find evidence for the thermal dissociation of H 2 O and H 2 on the planet's permanent dayside. Additionally, we detect SiO at a statistical significance of 5.2 σ , which is compatible with chemical equilibrium in the atmosphere. Constraining the abundance of SiO and abundance ratios between silicon and volatile atoms in WASP-121 b's atmosphere could help discriminate between possible migration histories of the planet. The three-dimensional nature of thermal dissociation on WASP-121 b's dayside and of recombination on its nightside, however, poses a challenge to constraining molecular abundances and elemental abundance ratios from the transmission spectrum. To account for this, we implemented an atmospheric model in the NEMESIS framework that splits the planet's atmosphere into dayside and nightside. A retrieval applying our atmospheric model to WASP-121 b's transmission spectrum favors a higher H 2 O abundance on the nightside than on the dayside, demonstrating the impact of hemispheric heterogeneity when attempting to constrain WASP-121 b's bulk H 2 O inventory.

<scp>ExoPhoto</scp>: A Database of Temperature-Dependent Photodissociation Cross Sections

2025-05-31
Qijian Ni , C. Hill , S. N. Yurchenko +5 more | RAS Techniques and Instruments
Abstract We present the ExoPhoto database https://exomol.com/exophoto/, an extension of the ExoMol database, specifically developed to address the growing need for high-accuracy, temperature-dependent photodissociation cross section data towards short-UV wavelengths. … Abstract We present the ExoPhoto database https://exomol.com/exophoto/, an extension of the ExoMol database, specifically developed to address the growing need for high-accuracy, temperature-dependent photodissociation cross section data towards short-UV wavelengths. ExoPhoto combines theoretical models from three major computational databases (ExoMol, UGAMOP and PhoMol) and experimental datasets from two experimental groups, providing extensive wavelength and temperature coverage. ExoPhoto currently includes photodissociation data for 20 molecules: AlH, HCl, HF, MgH, OH, NaO, MgO, O2, AlCl, AlF, CS, HeH+, CO, CO2, H2O, SO2, C2H2, C2H4, H2CO, and NH3, derived from theoretical models and supported by experimental data from 5 databases. ExoPhoto also includes detailed data on branching ratios and quantum yields for selected datasets. The data structure of ExoPhoto follows the ExoMol framework, with a consistent naming convention and hierarchical JSON-based organization. Photodissociation cross sections are stored in a set of .photo files which provide data as a function of wavelength with one file for each target molecule temperature. Future developments aim to include more photodissociation cross section data and to provide data for molecules in non-local thermodynamic equilibrium (non-LTE). These will expand the utility of ExoPhoto for advanced astrophysical, planetary modeling and industrial applications.

PyTICS: An Iterative Method for Photometric Lightcurve Intercalibration using Comparison Stars

2025-05-31
Roberta Vieliute , J V Hernández Santisteban , Keith Horne +1 more | RAS Techniques and Instruments
Abstract Intensive reverberation mapping monitoring programs combine ground-based photometric observations from different telescopes, requiring intercalibration of lightcurves to reduce systematic instrumental differences. We present a new iterative algorithm to calibrate … Abstract Intensive reverberation mapping monitoring programs combine ground-based photometric observations from different telescopes, requiring intercalibration of lightcurves to reduce systematic instrumental differences. We present a new iterative algorithm to calibrate photometric time-series data of active galactic nuclei (AGN) using 100s of comparison stars on the same images, building upon the established method of ensemble photometry. The algorithm determines telescope-specific and epoch-specific correction parameters, and simultaneously computes a multi-component noise model to account for underestimated uncertainties based on the scatter in the comparison star data, effectively identifying problematic epochs, telescopes, and stars. No assumptions need to be made about the AGN variability shape, and the algorithm can in principle be applied to any astronomical object. We demonstrate our method on lightcurves taken with ten 1-m telescopes from the Las Cumbres Observatory (LCO) robotic telescope network. Comparing our results to other intercalibration tools, we find that the algorithm can more accurately quantify the uncertainties in the data. We describe additional corrections that can be made for particularly bluer AGNs like Fairall 9, arising due to systematic effects dependent on star colour.

Accurate photometric calibration by fitting the system transmission

2025-05-30
S. Garrappa , E. O. Ofek , Sagi Ben-Ami +7 more | Astronomy and Astrophysics
Transforming the instrumental photometry of ground-based telescopes into a calibrated physical flux in a well-defined passband is a major challenge in astronomy. Along with the intrinsic instrumental difference between telescopes … Transforming the instrumental photometry of ground-based telescopes into a calibrated physical flux in a well-defined passband is a major challenge in astronomy. Along with the intrinsic instrumental difference between telescopes sharing the same filter, the effective transmission is continuously modified by the effects of the variable atmosphere of the Earth. We have developed a new approach to the absolute photometric calibration (i.e., tied to the CALSPEC standards) that simultaneously treats instrumental and atmospheric effects on an image-by-image basis by fitting the system transmission. This approach aims at breaking the 1% absolute photometric accuracy which limits current calibration methods for ground-based observatories. We fit the transmission, as a function of wavelength, for each image. The fit is done by comparing the instrumental fluxes of stars in the image to the synthetic photometry of the stars given their spectrum and the transmission function which have free parameters. A key element that enables this approach is the set of about 220 million low-resolution spectra measured by which provides a large number of stellar calibrators in the image that are calibrated against the CALSPEC scale. We demonstrate the method using data from the Large Array Survey Telescope (LAST). We show that the residuals between observations and synthetic photometry of the spectra in the fitted transmission have a standard deviation $&lt;$1% on an image-by-image basis, with no spatial and color dependencies. The median accuracy of the zero-point throughout the image is between 3-5 mmag, depending on the total image exposure. Furthermore we show that this method provides high stability over long temporal scales.

The atmospheres of rocky exoplanets. III. Using atmospheric spectra to constrain surface rock composition

2025-05-28
Oliver Herbort , L. Sereinig | Astronomy and Astrophysics
The crust composition of rocky exoplanets with substantial atmospheres cannot be observed directly. However, recent developments have enabled novel observations and characterisations of their atmospheres. We aim to establish a … The crust composition of rocky exoplanets with substantial atmospheres cannot be observed directly. However, recent developments have enabled novel observations and characterisations of their atmospheres. We aim to establish a link between observable spectroscopic atmospheric features and the mineralogical crust composition of exoplanets. This enables us to constrain the surface composition simply by observing the transit spectra. We used a diverse set of total element abundances inspired by various rock compositions, Earth, Venus, and CI chondrite as a basis for our bottom-to-top atmospheric model. We assumed thermal and chemical equilibrium between the atmosphere and the planetary surface. Based on the atmospheric models in hydrostatic and chemical equilibrium, with the inclusion of element depletion due to cloud formation, we calculated the theoretical transit spectra. The atmospheric type classification allows us to constrain the surface mineralogy, especially with respect to sulphur compounds, iron oxides and hydroxides, feldspars, silicates, and carbon species. Spectral features offer an opportunity to differentiate among the atmospheric types, allowing for a number of constraints to be placed on the surface composition.

Improved global estimates of terrestrial evapotranspiration using the MODIS and VIIRS sensors

2025-05-28
K. Arthur Endsley , Maosheng Zhao , John S. Kimball +2 more | Journal of Hydrometeorology
Abstract Terrestrial evapotranspiration (ET), as the link between water, energy, and carbon cycles, is key to understanding climate impacts on freshwater availability, agricultural yields, and forest mortality. Earth-observing sensors, such … Abstract Terrestrial evapotranspiration (ET), as the link between water, energy, and carbon cycles, is key to understanding climate impacts on freshwater availability, agricultural yields, and forest mortality. Earth-observing sensors, such as the Moderate Resolution Imaging Spectroradiometer (MODIS) carried by NASA’s Earth Observing System (EOS), are well-suited to the study of ET at regional to global scales. As the era of EOS comes to a close, we present a comprehensive calibration and validation of the latest MODIS MOD16 ET product as well as new ET estimates based on data from the Visible Infrared Imaging Radiometer Suite (VIIRS) sensor, which is very similar to MODIS and is carried by the Suomi NPP and NOAA-20 satellites, in order to continue the now 25-year record of ET estimates from MOD16. Substantial updates and improvements to MOD16 are reported for the first time in over a decade of widespread use. Ground data sources including tower latent heat fluxes and plant traits are used in a Bayesian model-data fusion to constrain MODIS- and VIIRS-based ET estimates. Independent validation against sapflow and tower data show that the resulting products have lower absolute bias and higher accuracy than the current MOD16 Collection 6.1 product. While MOD16 under-estimates cropland ET, an inter-comparison with the OpenET suite of models indicates that the improved MOD16 has the lowest error, lowest absolute bias, and highest model efficiency at non-cropland sites. In combination with MODIS primary productivity estimates, these updates to MOD16 ensure the continuity of multi-decadal ET and water-use efficiency estimates through 2030 or later.

Improved time constant of a newly released air temperature sensor and its implications

2025-05-28
Stephen Burt , Dirk V. Baker | Quarterly Journal of the Royal Meteorological Society
Abstract The World Meteorological Organization (WMO), National Oceanic and Atmospheric Administration, and other organizations provide guidance on expected response time for sensors used to measure air temperatures intended for meteorological … Abstract The World Meteorological Organization (WMO), National Oceanic and Atmospheric Administration, and other organizations provide guidance on expected response time for sensors used to measure air temperatures intended for meteorological applications. Quantified as the sensor time constant (the time it takes for a sensor to reflect some percentage of a step change), recommendations differ somewhat depending on the organization. For instance, the WMO specifies the 63% time constant should be ≤20 s, although, crucially, the organization does not state the air flow velocity at which this time constant should be achieved. Recent independent tests at two laboratory facilities (initially the University of Reading, United Kingdom, and subsequently at Campbell Scientific, Logan, Utah, United States) were undertaken to determine time constants of a range of commercially available platinum resistance thermometer sensors. Results showed that many sensors fell far short of the WMO specification at airflow rates typical of naturally ventilated thermometer screens or radiation shields (1 m·s −1 or lower). In contrast, a recently released platinum resistance thermometer sensor from Campbell Scientific was shown to meet both specifications, even at airflow rates within a laboratory wind tunnel as low as 0.2 m·s −1 , which is more typical of naturally ventilated thermometer screens or radiation shields. Across multiple sensors and repeated test runs, the new sensor's 63% response time averaged 10.7 s (standard deviation 0.5 s) at an airflow of 1 m·s −1 and 17.1 s (standard deviation 0.9 s) at 0.2 m·s −1 . To our knowledge, this is the first commercially available sensor to attain this WMO specification. However, using or switching to faster‐response sensors has important implications for long‐term data records, the measurement of extreme temperatures (specifically daily maximum and minimum data), and intersite comparisons. This is compounded by seemingly conflicting recommendations from the WMO regarding sensor time constant versus data processing methods.