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Improved modeling of cloudy‐sky actinic flux using satellite cloud retrievals
Author(s) -
Ryu YoungHee,
Hodzic Alma,
Descombes Gael,
Hall Samuel,
Minnis Patrick,
Spangenberg Douglas,
Ullmann Kirk,
Madronich Sasha
Publication year - 2017
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1002/2016gl071892
Subject(s) - satellite , environmental science , radiative transfer , troposphere , atmospheric sciences , sky , flux (metallurgy) , atmospheric radiative transfer codes , cloud computing , meteorology , remote sensing , geology , materials science , physics , optics , astronomy , computer science , metallurgy , operating system
Clouds play a critical role in modulating tropospheric radiation and thus photochemistry. We develop a methodology for calculating the vertical distribution of tropospheric ultraviolet (300–420 nm) actinic fluxes using satellite cloud retrievals and a radiative transfer model. We demonstrate that our approach can accurately reproduce airborne‐measured actinic fluxes from the 2013 Studies of Emissions and Atmospheric Composition, Clouds and Climate Coupling by Regional Surveys (SEAC 4 RS) campaign as a case study. The results show that the actinic flux is reduced below moderately thick clouds with increasing cloud optical depth and can be enhanced by a factor of 2 above clouds. Inside clouds, the actinic flux can be enhanced by up to 2.4 times in the upper part of clouds or reduced up to 10 times in the lower parts of clouds. Our study suggests that the use of satellite‐derived actinic fluxes as input to chemistry‐transport models can improve the accuracy of photochemistry calculations.