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| Titel |
Next-generation angular distribution models for top-of-atmosphere radiative flux calculation from CERES instruments: validation |
| VerfasserIn |
W. Su, J. Corbett, Z. Eitzen, L. Liang |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1867-1381
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| Digitales Dokument |
URL |
| Erschienen |
In: Atmospheric Measurement Techniques ; 8, no. 8 ; Nr. 8, no. 8 (2015-08-14), S.3297-3313 |
| Datensatznummer |
250116531
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| Publikation (Nr.) |
 copernicus.org/amt-8-3297-2015.pdf |
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| Zusammenfassung |
| Radiative fluxes at the top of the atmosphere (TOA) from the Clouds and the
Earth's Radiant Energy System (CERES) instrument are fundamental variables
for understanding the Earth's energy balance and how it changes with time.
TOA radiative fluxes are derived from the CERES radiance measurements using
empirical angular distribution models (ADMs). This paper evaluates the
accuracy of CERES TOA fluxes using direct integration and flux consistency
tests. Direct integration tests show that the overall bias in regional
monthly mean TOA shortwave (SW) flux is less than 0.2 Wm−2 and the RMSE is less than 1.1 Wm−2. The bias and RMSE are very similar
between Terra and Aqua. The bias in regional monthly mean
TOA LW fluxes is less than 0.5 Wm−2 and the RMSE is less than 0.8 Wm−2 for both Terra and Aqua. The accuracy of the TOA
instantaneous flux is assessed by performing tests using fluxes inverted from
nadir- and oblique-viewing angles using CERES along-track observations and
temporally and spatially matched MODIS observations, and using fluxes
inverted from multi-angle MISR observations. The averaged TOA instantaneous
SW flux uncertainties from these two tests are about 2.3 % (1.9 Wm−2)
over clear ocean, 1.6 % (4.5 Wm−2) over clear land, and 2.0 % (6.0 Wm−2) over clear snow/ice; and are about 3.3 % (9.0 Wm−2), 2.7 %
(8.4 Wm−2), and 3.7 % (9.9 Wm−2) over ocean, land, and snow/ice
under all-sky conditions. The TOA SW flux uncertainties are generally larger
for thin broken clouds than for moderate and thick overcast clouds. The TOA
instantaneous daytime LW flux uncertainties derived from the CERES-MODIS test
are 0.5 % (1.5 Wm−2), 0.8 % (2.4 Wm−2), and 0.7 % (1.3 Wm−2)
over clear ocean, land, and snow/ice; and are about 1.5 % (3.5 Wm−2),
1.0 % (2.9 Wm−2), and 1.1 % (2.1 Wm−2) over ocean, land, and
snow/ice under all-sky conditions. The TOA instantaneous nighttime LW flux
uncertainties are about 0.5–1 % (< 2.0 Wm−2) for all surface types.
Flux uncertainties caused by errors in scene identification are also assessed
by using the collocated CALIPSO, CloudSat, CERES and MODIS data product.
Errors in scene identification tend to underestimate TOA SW flux by about 0.6 Wm−2 and overestimate
TOA daytime (nighttime) LW flux by 0.4 (0.2) Wm−2 when all CERES viewing angles are considered. |
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