地表反照率与高原夏季风爆发关系分析

Indicative Significance of Land Surface Albedo over the Tibetan Plateau to the Onset of Plateau Summer Monsoon

利用2000~2016年MODIS地表反照率和ECMWF/ERA-Interim再分析资料,选取有代表性的高原季风指数DPMI,统计分析了青藏高原地表反照率与高原季风之间的联系,结果表明:1)11月高原地表反照率大小与次年高原夏季风爆发存在密切关系:11月高原地表反照率偏低(高),次年4月高原夏季风爆发偏早(晚),强度偏强(弱)。2)可能的影响机制为:当前期11月高原地表反照率偏低时,后期高原主体对大气的感热加热信号更强,从而引起4月高原上空近地面层上升运动明显加强,这有利于热量向高空传输,导致对流层加热作用加强,高原上空对流层温度偏高,使得高原季风环流系统加强,最终导致高原季风季节变化相应提前;反之亦然。

In this study,the relationship between the land surface albedo over the Tibetan Plateau and the plateau summer monsoon are statistically analyzed using a representative plateau monsoon index,i.e.,Dynamic Plateau Monsoon Index(DPMI)based on MODIS surface albedo and ECMWF/ERA-Interim reanalysis data from 2000 to 2016.The main results are as follows:1)There is a close relationship between the land surface albedo over the Tibetan Plateau in November and the onset of plateau summer monsoon.The land surface albedo of the Tibetan Plateau in November is low(high),and the plateau summer monsoon starts early(late)in April of the following year.2)When the land surface albedo over the Tibetan Plateau in November is low,the sensible heat flux of the main body of the plateau on the atmosphere is strong in the latter period,which significantly strengthens the uplifting movement of the plateau in April.Thus,the plateau becomes conducive to the transfer of heat to the upper air,resulting in enhanced tropospheric heating,increased tropospheric temperature in the plateau,and strengthened plateau monsoon circulation system,eventually leading to the early plateau monsoon seasonal changes,and vice versa.