ABSTRACT Imagers on geostationary (GEOSat) and low-earth orbiting (LEOSat) satellites are often u... more ABSTRACT Imagers on geostationary (GEOSat) and low-earth orbiting (LEOSat) satellites are often used to derive information about clouds and the surface, but are limited in their angular coverage of a given scene by their particular orbits. A GEOSat views an area through its entire diurnal cycle covering the full range of solar zenith angles (SZAs) while viewing from a constant viewing zenith angle (VZA) and varying relative azimuth angle (RAA). Most polar-orbiting satellites are sun-synchronous and view a given area at one time of day from various VZAs and RAAs, but a over a small SZA range. A few imagers such as MISR or AATSR are on LEOSats and can provide views over a greater range of RAA and VZA, but are still constrained by SZA. The Deep Space Climate Observatory (DSCOVR) will orbit at the L-1 position in a near backscatter angle (~168°) relative to the Earth and sun. It carries an imager, EPIC, that has several UV, visible, and near-infrared channels measuring radiances at a nadir 10-km resolution. Because it views most of the sunlit Earth at high frequency, it can provide unprecedented coverage of the daylight portion of the diurnal cycle for a given area at over the full range of SZAs and VZAs at a nearly constant RAA. Because of this coverage, pixels from the EPIC can be matched with those from any other satellite passing over the sunlit hemisphere. Although cloud information such as cloud amount, optical depth, and height can be derived from the EPIC channels, the combination of EPIC data with that from higher resolution GEOSats and LEOSats will be more useful than either by itself. Because of its low resolution and lack of infrared data, broken and scattered and cirrus cloud fields are likely to be misinterpreted using the EPIC data alone. Matching the more conventional satellite data and associated cloud products with the EPIC data will enhance the information from the EPIC as its field of view increases as 1/cos(VZA). The cloud heights derived from oxygen A and B bands will be improved by knowing the cloud fraction and type more accurately. Multiangle views from the matched satellite data will provide information about cirrus cloud particle habit, multilayer cloud conditions, and, possibly, the width of the droplet size spectrum. Better definition of clear areas and cloud conditions within the EPIC fields of view will be realized by inclusion of matched data, so that retrievals of other parameters such as leaf area index can be determined more accurately, without cloud contamination. This paper will explore these and other potential uses of combining real-time NASA Langley cloud data from LEOSats and GEOSats.
Meteorological satellite instrument pixel sizes are often much greater than the individual cloud ... more Meteorological satellite instrument pixel sizes are often much greater than the individual cloud elements in a given scene. Partially cloud-filled pixels can be misinterpreted in many analysis schemes because the techniques usually assume that all of the cloudy pixels are cloud filled. Coincident Landsat and Geostationary Operational Environmental Satellite (GOES) data and degraded-resolution Landsat data were used to study the effects of both sensor resolution and analysis techniques on satellite-derived cloud parameters. While extremely valuable for advancing the understanding of these effects, these previous studies were relatively limited in the number of cloud conditions that were observed and by the limited viewing and illumination conditions. During the First ISCCP Regional Experiment (FIRE) Phase 2 (13 Nov. - 7 Dec. 1991), the NASA ER-2 made several flights over a wide range of cloud fields and backgrounds with several high resolution sensors useful for a variety of purposes...
Journal of Geophysical Research: Atmospheres, 2016
The Studies of Emissions and Atmospheric Composition, Clouds and Climate Coupling by Regional Sur... more The Studies of Emissions and Atmospheric Composition, Clouds and Climate Coupling by Regional Surveys (SEAC4RS) field mission based at Ellington Field, Texas, during August and September 2013 employed the most comprehensive airborne payload to date to investigate atmospheric composition over North America. The NASA ER‐2, DC‐8, and SPEC Inc. Learjet flew 57 science flights from the surface to 20 km. The ER‐2 employed seven remote sensing instruments as a satellite surrogate and eight in situ instruments. The DC‐8 employed 23 in situ and five remote sensing instruments for radiation, chemistry, and microphysics. The Learjet used 11 instruments to explore cloud microphysics. SEAC4RS launched numerous balloons, augmented AErosol RObotic NETwork, and collaborated with many existing ground measurement sites. Flights investigating convection included close coordination of all three aircraft. Coordinated DC‐8 and ER‐2 flights investigated the optical properties of aerosols, the influence of...
Several recent studies have shown decadal variation in Top of Atmosphere (TOA) shortwave (SW) ref... more Several recent studies have shown decadal variation in Top of Atmosphere (TOA) shortwave (SW) reflected and longwave (LW) thermal infrared emitted fluxes from satellite, as well as SW insolation at the surface. This paper will show the variations found in both ERBS and CERES satellite radiation budget data, including recent algorithm and calibration improvements in each time series. Results will be shown both for tropical as well as global mean variations, and compared to other satellite flux estimates including ISCCP FD, and AVHRR and HIRS Pathfinder datasets. Global results will be compared against independent global ocean heat storage data. The results show significant changes that are consistent with ocean heat storage variability through 2002. Interannual variations are large and suggest a tight coupling of changes in net cloud radiative forcing and ocean heat storage. Implications are considered for studies of cloud feedback in climate models, as well as for design of future c...
The top-of-atmosphere (TOA) Earth radiation budget (ERB) is a key property of the climate system ... more The top-of-atmosphere (TOA) Earth radiation budget (ERB) is a key property of the climate system that describes the balance between how much solar energy the Earth absorbs and how much terrestrial thermal infrared radiation it emits. This article provides an overview of the instruments and algorithms used to observe the TOA ERB by the Clouds and the Earth’s Radiant Energy System (CERES) project. We summarize the properties of the CERES instruments, their calibration, combined use of CERES and imager measurements for improved cloud-radiation properties, and the approaches used for time interpolation and space averaging of TOA radiative fluxes.
ABSTRACT Imagers on geostationary (GEOSat) and low-earth orbiting (LEOSat) satellites are often u... more ABSTRACT Imagers on geostationary (GEOSat) and low-earth orbiting (LEOSat) satellites are often used to derive information about clouds and the surface, but are limited in their angular coverage of a given scene by their particular orbits. A GEOSat views an area through its entire diurnal cycle covering the full range of solar zenith angles (SZAs) while viewing from a constant viewing zenith angle (VZA) and varying relative azimuth angle (RAA). Most polar-orbiting satellites are sun-synchronous and view a given area at one time of day from various VZAs and RAAs, but a over a small SZA range. A few imagers such as MISR or AATSR are on LEOSats and can provide views over a greater range of RAA and VZA, but are still constrained by SZA. The Deep Space Climate Observatory (DSCOVR) will orbit at the L-1 position in a near backscatter angle (~168°) relative to the Earth and sun. It carries an imager, EPIC, that has several UV, visible, and near-infrared channels measuring radiances at a nadir 10-km resolution. Because it views most of the sunlit Earth at high frequency, it can provide unprecedented coverage of the daylight portion of the diurnal cycle for a given area at over the full range of SZAs and VZAs at a nearly constant RAA. Because of this coverage, pixels from the EPIC can be matched with those from any other satellite passing over the sunlit hemisphere. Although cloud information such as cloud amount, optical depth, and height can be derived from the EPIC channels, the combination of EPIC data with that from higher resolution GEOSats and LEOSats will be more useful than either by itself. Because of its low resolution and lack of infrared data, broken and scattered and cirrus cloud fields are likely to be misinterpreted using the EPIC data alone. Matching the more conventional satellite data and associated cloud products with the EPIC data will enhance the information from the EPIC as its field of view increases as 1/cos(VZA). The cloud heights derived from oxygen A and B bands will be improved by knowing the cloud fraction and type more accurately. Multiangle views from the matched satellite data will provide information about cirrus cloud particle habit, multilayer cloud conditions, and, possibly, the width of the droplet size spectrum. Better definition of clear areas and cloud conditions within the EPIC fields of view will be realized by inclusion of matched data, so that retrievals of other parameters such as leaf area index can be determined more accurately, without cloud contamination. This paper will explore these and other potential uses of combining real-time NASA Langley cloud data from LEOSats and GEOSats.
Meteorological satellite instrument pixel sizes are often much greater than the individual cloud ... more Meteorological satellite instrument pixel sizes are often much greater than the individual cloud elements in a given scene. Partially cloud-filled pixels can be misinterpreted in many analysis schemes because the techniques usually assume that all of the cloudy pixels are cloud filled. Coincident Landsat and Geostationary Operational Environmental Satellite (GOES) data and degraded-resolution Landsat data were used to study the effects of both sensor resolution and analysis techniques on satellite-derived cloud parameters. While extremely valuable for advancing the understanding of these effects, these previous studies were relatively limited in the number of cloud conditions that were observed and by the limited viewing and illumination conditions. During the First ISCCP Regional Experiment (FIRE) Phase 2 (13 Nov. - 7 Dec. 1991), the NASA ER-2 made several flights over a wide range of cloud fields and backgrounds with several high resolution sensors useful for a variety of purposes...
Journal of Geophysical Research: Atmospheres, 2016
The Studies of Emissions and Atmospheric Composition, Clouds and Climate Coupling by Regional Sur... more The Studies of Emissions and Atmospheric Composition, Clouds and Climate Coupling by Regional Surveys (SEAC4RS) field mission based at Ellington Field, Texas, during August and September 2013 employed the most comprehensive airborne payload to date to investigate atmospheric composition over North America. The NASA ER‐2, DC‐8, and SPEC Inc. Learjet flew 57 science flights from the surface to 20 km. The ER‐2 employed seven remote sensing instruments as a satellite surrogate and eight in situ instruments. The DC‐8 employed 23 in situ and five remote sensing instruments for radiation, chemistry, and microphysics. The Learjet used 11 instruments to explore cloud microphysics. SEAC4RS launched numerous balloons, augmented AErosol RObotic NETwork, and collaborated with many existing ground measurement sites. Flights investigating convection included close coordination of all three aircraft. Coordinated DC‐8 and ER‐2 flights investigated the optical properties of aerosols, the influence of...
Several recent studies have shown decadal variation in Top of Atmosphere (TOA) shortwave (SW) ref... more Several recent studies have shown decadal variation in Top of Atmosphere (TOA) shortwave (SW) reflected and longwave (LW) thermal infrared emitted fluxes from satellite, as well as SW insolation at the surface. This paper will show the variations found in both ERBS and CERES satellite radiation budget data, including recent algorithm and calibration improvements in each time series. Results will be shown both for tropical as well as global mean variations, and compared to other satellite flux estimates including ISCCP FD, and AVHRR and HIRS Pathfinder datasets. Global results will be compared against independent global ocean heat storage data. The results show significant changes that are consistent with ocean heat storage variability through 2002. Interannual variations are large and suggest a tight coupling of changes in net cloud radiative forcing and ocean heat storage. Implications are considered for studies of cloud feedback in climate models, as well as for design of future c...
The top-of-atmosphere (TOA) Earth radiation budget (ERB) is a key property of the climate system ... more The top-of-atmosphere (TOA) Earth radiation budget (ERB) is a key property of the climate system that describes the balance between how much solar energy the Earth absorbs and how much terrestrial thermal infrared radiation it emits. This article provides an overview of the instruments and algorithms used to observe the TOA ERB by the Clouds and the Earth’s Radiant Energy System (CERES) project. We summarize the properties of the CERES instruments, their calibration, combined use of CERES and imager measurements for improved cloud-radiation properties, and the approaches used for time interpolation and space averaging of TOA radiative fluxes.
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