Premium
Determining the Shortwave Radiative Flux From Earth Polychromatic Imaging Camera
Author(s) -
Su Wenying,
Liang Lusheng,
Doelling David R.,
Minnis Patrick,
Duda David P.,
Khlopenkov Konstantin,
Thieman Mandana M.,
Loeb Norman G.,
Kato Seiji,
Valero Francisco P. J.,
Wang Hailan,
Rose Fred G.
Publication year - 2018
Publication title -
journal of geophysical research: atmospheres
Language(s) - English
Resource type - Journals
eISSN - 2169-8996
pISSN - 2169-897X
DOI - 10.1029/2018jd029390
Subject(s) - daytime , shortwave , environmental science , remote sensing , epic , flux (metallurgy) , satellite , atmospheric sciences , radiative transfer , physics , geology , optics , materials science , astronomy , metallurgy , art , literature
The Earth Polychromatic Imaging Camera (EPIC) onboard Deep Space Climate Observatory provides 10 narrowband spectral images of the sunlit side of the Earth. The blue (443 nm), green (551 nm), and red (680 nm) channels are used to derive EPIC broadband radiances based upon narrowband‐to‐broadband regressions developed using collocated MODIS equivalent channels and Clouds and the Earth's Radiant Energy System (CERES) broadband measurements. The pixel‐level EPIC broadband radiances are averaged to provide global daytime means at all applicable EPIC times. They are converted to global daytime mean shortwave (SW) fluxes by accounting for the anisotropy characteristics using a cloud property composite based on lower Earth orbiting satellite imager retrievals and the CERES angular distribution models (ADMs). Global daytime mean SW fluxes show strong diurnal variations with daily maximum‐minimum differences as great as 20 W/m 2 depending on the conditions of the sunlit portion of the Earth. The EPIC SW fluxes are compared against the CERES SYN1deg hourly SW fluxes. The global monthly mean differences (EPIC‐SYN) between them range from 0.1 W/m 2 in July to −4.1 W/m 2 in January, and the RMS errors range from 3.2 to 5.2 W/m 2 . Daily mean EPIC and SYN fluxes calculated using concurrent hours agree with each other to within 2% and both show a strong annual cycle. The SW flux agreement is within the calibration and algorithm uncertainties, which indicates that the method developed to calculate the global anisotropic factors from the CERES ADMs is robust and that the CERES ADMs accurately account for the Earth's anisotropy in the near‐backscatter direction.