Region Change Of Asian Arid And Semiarid Area In Recent Years

Using the ERA-40 reanalysis data, characteristics of the correlation between the precipitation of Asian arid and semiarid region and the ocean warm pool sea surface temperatures (SSTs), water vapor changes are investigated. The results show that the deseasonalised water vapor and precipitation in Asian arid and semi-arid region exhibit a distinct positive correlation with deseasonalised SSTs and water vapor over the ocean warm pools.The correlation is most significant in the East Indian Ocean Warm Pool 1 (EIOWP1) and relatively weak in El Nino 1+2,but the correlations with El Nino regions become stronger when El Nino region is closer to the centre pacific region. The summer precipitation of the Asian arid and semi-arid region is well correlated with the ocean warm pool SSTs in all seasons. However, the winter and spring precipitation of the Asian arid and semi-arid region have no significant correlation with the ocean warm pool SSTs. The quickest response of the precipitation in the Asian arid and semi-arid region to the ocean warm pool SSTs is associated with EIOWP1 with a time lag of 1-3 months, and the slowest response corresponds to the west pacific warm pool (WPWP) with a time lag of 4 months.The analysis also reveals that the precipitation increases in the Asian arid and semi-arid region tends to increase during El Nino year winter and La Nina year summer. The changes in intensities of the Indian Monsoon, East Asian Monsoon, westerly and ENSO impact, to a large extent, on the water vapor changes over the Asia arid and semiarid region which are related to water vapor changes over the ocean warm pool.The results suggest that the water vapor and precipitation in Asian arid and semi-arid region is increasing due to the increasing Indian Monsoon index and decreasing westerlies in recent years. The high clouds are found to be decreasing in recent years, however, the medium and low could amount is increasing over the study area suggesting that the increases in low level convective precipitation are responsible for the wetting of the region. Analysis of the temperature trends in the lower and upper troposphere reveals that the intensified upper level anticyclone caused by significant cooling of upper troposphere may enhance convective activities. We conducted three control run shown if Sea Surface Temperature (SST) is on the increase, water vapor will be increasing in Asia arid and semi-arid.