FGOALS模式对中国西南地区干旱气候的模拟研究

本文利用台站资料、NCEP资料及FGOALS模式结果对全球变暖背景下西南地区的干旱及其成因进行比较分析,结果表明:西太平洋副热带高压较常年异常偏弱偏东,中高纬环流场比较平直;由南向北的水汽输送较常年偏弱,中低层水汽通量和湿润年相比表现为辐散;而西南地区上游的青藏高原地区对流活动减弱,低涡活动减弱,都是导致该地区降水偏少,从而形成高温干旱的主要原因。与NCEP资料相比,FGOALS模式模拟的中高层位势高度偏低,越往高层,偏差越大;FGOALS模拟的暖湿水汽输送位置较为偏南;垂直运动大值区偏西。 

Simulations of the Drought in Southwestern China by the Coupled Model FGOALS

The phenomenon and causes of drought in southwestern China under the background of global warming are studied by the coupled model FGOALS and compared with the observed station data and the NCEP reanalysis dataset.Analyses show that during the drought the subtropical high in the western Pacific is weaker and displaces eastward than in the normal year and the atmospheric circulation in the mid-high latitudes is smoother with a weaker activity of cold air.These lead to a weaker northward water vapor transportation to the western edge of the subtropical high.The water vapor fluxes in the low-mid levels appears anomalous divergences compared to the wet years.Thus,the weakening of convection over the Tibetan Plateau in the upper reach of southwestern China is a main cause of the reduction of precipitation and high temperature over the southwestern China.The geopotential height simulated by FGOALS is lower than that in the NCEP reanalysis in the mid-high levels and the biases increase upward.As simulated by FGOALS,the water vapor transportation locates to the south compared with the observation and the convection is displaced westward.