Model estimates of the influence of different single-layer cloud types on the shortwave balance in Western Siberia
I.M. Nasrtdinov, K.V. Kuryanovich, T.B. Zhuravleva, A.V. Skorokhodov
V.E. Zuev Institute of Atmospheric Optics of Siberian Branch of the Russian Academy of Science, Tomsk, Russia
Keywords: radiation balance of Earth’s surface, solar radiation, water and ice clouds, Western Siberia, numerical simulation, cloud radiative forcing
Abstract
Cloudiness is one of the main factors determining the processes of radiation transfer in the atmosphere; it plays a key role in the formation of the radiative balance of the Earth’s surface. The paper analyzes the impact of various single-layer cloud cover types on the shortwave balance of underlying surface (SBS) obtained using broadband flux simulation and long-term atmospheric remote sensing data for northern and southern regions of Western Siberia. Calculations performed for cloud characteristics averaged over the period 2001-2019 revealed that an increase in the cloud optical thickness decreases the daily SBS in summer from ~ 25 to ~ 8 MJ/m2, while an increase in the underlying surface albedo in winter significant decreases the radiation balance, down to ~ 0.4-1 MJ/m2. The presented estimates of the cloud radiative forcing (CRF) demonstrate its increase with the optical thickness of clouds from -60 W/m2 (thin ice clouds) to -200 W/m2 (dense cirrus clouds and middle-level clouds) in summer, and a significant decrease in the CRF modulus (to 4-7 W/m2) in winter. The SBS estimates can be considered as the regional averages for the cloud types under study.
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