Variation Of The Tibetan Plateau Summer Monsoon And Its Effect On The Rainfall And The Circulation In Asia

Using observational and reanalysis data, the variation of the Tibetan Plateau Summer Monsoon (TPSM) and its relationship with the India Summer Monsoon (ISM) and the East Asian Summer Monsoon (EASM) are investigated in terms of the correlation analysis and the composite analysis. The chief conclusions are as follows: The seasonal characteristics of the meteorological elements are obvious in its abnormal strong phase, so we choose a summer as the research object. The results show that the TPSM in 2008 is earlier and stronger than the normal. The most significant period of the intra-seasonal oscillation in the TPSM is bi-weekly, similar to all ISM rainfall and the EASM index. When the TPSM is strong (weak), the precipitation in all India and North China tends to be less (more) than normal. During the active phase of the TPSM, the position of the Indian-Burma monsoon trough is to the east and north of its normal place, so that the moisture transportation in front of the trough is benefit to the rainfall on the southwest of the Tibetan Plateau (TP), but the ISM breaks for the influence of the high ridge over the Indian continent. Meanwhile, since the West Pacific Subtropical High (WPSH) is to the east and the south of its usual location, the EASM precipitation is concentrated on area of the East China. On the contrary, when the TPSM is weaker, as the WPSH expanding westward and shifting northward, the lower southwesterly jet shifts northward, thus both the southwesterly moisture transportation from the lower latitude and the southeasterly moisture transportation from the south edge of the WPSH contribute to the more precipitation in the North China. It's also shown that the TPSM oscillation related diabatic heating modulates the behavior of the South Asian High (SAH) to a considerable degree. The similar results can be found in the other years.