The Relationship Of The Indian Summer Monsoon Trough And The South China Sea Summer Monsoon Trough To The Precipitation Of Main Flood Season In Low Latitude Plateau

The Asian monsoon system has always been considered to be the most powerful monsoon system in the world, whose members includes the Indian summer monsoon and the east Asian summer monsoon.The low latitude plateau is located in somewhere between the bay of Bengal and south China sea,which is influenced by a combination of the Indian summer monsoon and east Asian summer monsoon.The outbreak of the monsoon time, active strength and so on will directly affect the weather and climate of low latitude plateau.In this paper, on the basis of previous studies, possible impacts of the Indian summer monsoon trough and the south China sea summer monsoon trough on the precipitation of main flood season in low latitude plateau are studied.The conclusions are as follows:(1) We found from the results of the SVD analysis that,the relative vorticity in Indian summer monsoon trough area and the relative vorticity in south China sea summer monsoon trough area is significant negative correlation to the precipitation of main flood season in low latitude plateau.(2) By Using composite analysis of several meteorological elements,We can get this conclusion:When the two summer monsoon trough are stronger (weaker),the Indian summer monsoon trough will inspires an anomalous cyclonic (anticyclone) circulation over the bay of Bengal.The Southwester becomes weaker (stronger) from the bay of Bengal,and the water vapor from the bay of Bengal to the low latitude plateau region is less (more).The subtropical high and the south China sea summer monsoon trough is stronger (weaker), and they inspire an anomalous cyclonic (anticyclone) circulation over the south China sea. There is anomalous east (west) wind on the north of the south China sea summer monsoon trough, and the water vapor from the south China sea to the low latitude plateau region is more (less) than normal.But due to the water vapor over the low latitude plateau is mainly from the bay of Bengal.amount of water vapor into the low latitude plateau area is still less (more) than normal.Influenced by two anomalous cyclonic (anticyclonic) circulation,there is an anomalous anticyclonic (cyclonic) circulation over the low latitude plateau area, and the divergence strengthened (weakened).Thus,the precipitation of main flood season in low latitude plateau area is less (more) than normal.(3) By choosing different simulation area and simulation integration time,we designed 6 tests,and then simulated these tests using WRF mesoscale numerical model.The simulation results of the same areas and different simulation time show that:When the Indian summer monsoon trough and the south China sea summer monsoon trough are stronger (weaker),There are two anomalous cyclonic (anticyclonic) circulation at the bay of Bengal and south China sea respectively.And the Precipitation of main flood season in low latitude plateau area is less (more).(4) The simulation results of the same simulation time and different simulation areas show that:the water vapor in the main flood season in low latitude plateau is mainly from the bay of Bengal.And The south China sea summer monsoon trough will hinder the water vapor which from the bay of Bengal to the low latitude plateau area,reduce the delivery amount of water vapor to the low latitude plateau area.