青藏高原上中尺度对流系统东移传播成因

运用1998年夏季日本静止气象卫星探测反演出的红外辐射亮温资料,对青藏高原上的中尺度对流系统(MCSs)进行了自动追踪,进而对移出高原的MCSs进行了分类,在此基础上,运用空间数据挖掘中的决策树方法得到了东移出高原的MCSs与其环境物理量场之间的关系,结果表明,在400hPa上,当MCSs的中心位置位于100°E附近时,移出高原且向东南方向移动的MCSs仅与该等压面上的高度和温度有关;而向东北方向移动的MCSs仅与高度和假相当位温有关;此外,移出高原且方向向东的MCSs主要决定于等压面高度、散度、涡度和假相当位温这4个物理量值。在500hPa上,位于东经104°E以西且最终移出高原的MCSs,决定其是否移向东北方向的环境物理量因素为K指数和水汽通量散度,而影响其向东南及东方向移动的因素则较多。

Mining Eastward-moving MCSs Features over the Tibetan Platean

In this paper, we automatically trace the movement routes of MCSs over the Tibetan Plateau using GMS infrared black body temperature (Tbb) in summer of 1998, while the MCSs are classified according to their move direction.Based on this, the relationships of eastward-moving MCSs features over the Tibetan Plateau and its environment physical field values are obtained using decision tree technique. Results indicated that in 400hPa, when the gravity center location of MCSs is near 100°E, the south east ward moving MCSs that has moved out of the Plateau is only related to the height and temperature over this constant pressure surface;the northeast ward moving MCSs is only related to the height and potential pseudo equivalent temperature; further more, the eastward-moving MCSs that has already moved out of the Plateau mainly depends on four physical values of constant pressure surface height, divergent, vortex and the potential pseudo-equivalent temperature. While in 500hPa, the northeast ward movement of MCSs are mainly influenced by K index and water vapor flux divergent when they lie west to the 104°E, however, to the eastward or southeastward moving MCSs, they are influenced by more factors in this layer.