How Does the Tibetan Plateau Affect the Transition of Indian Monsoon Rainfall
How Does the Tibetan Plateau Affect the Transition of Indian Monsoon Rainfall
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DOI：
10.1175/mwr3386.1
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发表时间：
2007-05
影响因子：
3.2
通讯作者：
Tomonori Sato;F. Kimura
中科院分区：
文献类型：
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作者：
Tomonori Sato;F. Kimura
NCEP-NCAR再分析资料显示，在南亚季风开始前，印度北部地区普遍存在对流层中层下降气流，这可以被认为是降水的抑制因素。下降运动在7月前逐渐减弱并从该区域撤退，与季风降水的西北迁移相一致。为了验证TP的动力和热力效应导致对流层中下沉及其季节变化的假设，采用简化的区域气候模式进行了一系列数值试验。冬季和春季纬向西风较强时，TP的机械效应在印度北部产生了较强的下降气流，但4月以后随着西风的减弱而减弱....
Abstract The roles of the Tibetan Plateau (TP) upon the transition of precipitation in the south Asian summer monsoon are investigated using a simplified regional climate model. Before the onset of the south Asian monsoon, descending flow in the midtroposphere, which can be considered as a suppressor against precipitation, prevails over northern India as revealed by the NCEP–NCAR reanalysis data. The descending motion gradually weakens and retreats from this region before July, consistent with the northwestward migration of the monsoon rainfall. To examine a hypothesis that the dynamical and thermal effects of TP cause the midtropospheric subsidence and its seasonal variation, a series of numerical experiments are conducted using a simplified regional climate model. The mechanical effect of the TP generates robust descending flow over northern India during winter and spring when the zonal westerly flow is relatively strong, but the effect becomes weaker after April as the westerly flow tends to be weaker....