Downward surface shortwave radiation over the subtropical Asia-Pacific region simulated by CMIP5 models

The downward surface shortwave radiation （DSSR） over the subtropical Asia-Pacific region simulated by the historical experiments of 15 CMIPS models is evaluated in this study.The simulated DSSR is compared against two satellite observational datasets, and the possible causes for the DSSR bias of the models are further investigated by dividing the subtropical Asia-Pacific region into five areas. Most of the CMIP5 models underestimate DSSR over the oceans, but overestimate DSSR over land. Aside from the Mediterranean-West Asia （MWA） and Central Asia （CA） areas, both the biases in annual and seasonal mean DSSR are well explained by the bias in surface shortwave cloud radiative forcing （CRF）, with an overestimation of the CRF effect over the subtropical North Pacific but an underestimation over other land regions. The effect of cloud plays a dominant role over the subtropical Asia-Pacific region, with relatively weaker influences over MWA and CA in boreal summer and fall.

本文以两套卫星观测资料为参考,评估了15个CMIP5气候模式对亚太地区太阳总辐射(DSSR)的模拟能力,并将亚太地区按经度位置划分成五个子区域来更好地分析模式误差的成因。许多CMIP5模式在海洋上低估了DSSR,而在陆地上却高估了DSSR。除了地中海-西亚(MWA)和中亚(CA),在年平均或季节平均尺度上,地表短波云辐射强迫(CRF)的误差都能很好地解释CMIP5模式中DSSR的主要误差来源:模式在海洋上高估了CRF的影响,而在陆地上低估了CRF的影响。云是影响亚太地区CMIP5模式中DSSR质量的主要因素,但是其在MWA和CA区域的影响相对较弱,特别是在北方的夏季和秋季。