Simulation of Snow Cover Fraction Over Eurasia Determined by FGOALS

Abstract

The twenteith century seasonal Snow Cover Fraction (SCF) over Eurasia, as simulated by two versions of the Flexible Global Ocean–Atmosphere–Land System (FGOALS) model, grid-point version 2 (g2) and spectral version 2 (s2), were compared with SCF data of the National Oceanic and Atmospheric Administration (NOAA) visible satellite and Moderate-resolution Imaging Spectroradiometer (MODIS). In general, both models effectively presented the spatial pattern of SCF over Eurasia, excluding the Tibetan Plateau, with an average spatial correlation coefficient of approximately 0.85 over all months. The SCF in the annual cycle simulation over non-summer seasons was larger in g2 than that in s2; the difference was most pronounced in late winter and spring. Root–mean–square–error (RMSE) results revealed that the seasonal cycle of SCF simulated by g2 had less error than that by s2. The analysis showed that the difference of temperature between the two models is the primary driver for the discrepancy in SCF in the annual cycle simulation. In addition, both models effectively simulated the significant decreasing trend over 30–70°N in winter during 1971–1994. However, because g2 showed a weak response to the increase in the concentration of CO₂ and little climate sensitivity, inter-annual variation was weaker than that in s2.