The Influence Of The Heat Source Of The Qinghai-Tibet Plateau And The North Atlantic SST On The Interdecadal Variation Of The Asian Summer Monsoo

The Atlantic multidecadal oscillation（AMV）and the atmospheric heat source over Tibetan Plateau（TPHS）are two important factors affecting the Asian summer monsoon（ASM）.Previous studies mainly focused on the influence of TP horizontal heating（vertical integrated heat source）on Asian monsoon.However,TP heating has obvious vertical characteristics,and the effect of TP vertical heating（TPVH）on Asian monsoon is still unclear.In addition,the actual relationship among AMV,TPHS and East Asian summer monsoon rainfall is still unknown.In the paper,we investigate the impacts of Tibetan Plateau vertical heating（TPVH）on the ASM,the distinct relationship between the AMV and TPHS,and the role of TP in the impact of AMV on the East Asian summer monsoon（EASM）on the interdecadal scale since the beginning of the 20th century.The main conclusions of this paper are as follows:In summer,the atmosphere over TP is heat source.For the climatic average of the apparent heat source over TP,the values over the southern part is higher than that over the northern part in the horizontal direction,and in the zonal vertical cross section,the values are positive in most parts of the troposphere.The southern flank of the Himalayas and the northern part of the Indian Peninsula are areas with great annual variation of heat source in summer.Since the beginning of 20^th century,the heat source over TP has shown a weakening trend.The latent heat of water vapor condensation makes the greatest contribution to the climatic average and variation of the heat source among the three components.The ASM,corresponding to TPVH,generally enhances on the interdecadal scale.In the upper troposphere,the upper-level westerly and easterly jet streams shift northwards in Asia,with two meridional“southern low and northern high”wave-like patterns dominating in East Asia and India,respectively.In the lower troposphere,the summer monsoonal airflow and convergence zone migrate northwards in Asia,and two meridional“southern high and northern low”patterns appear in East Asia and India,respectively.Thus,TPVH can strengthen the baroclinicity over northern East Asia and northern India,but weaken it over southern East Asia and southern India.Moreover,two anomalous meridional circulation cells are identified in East Asia and India,with ascending branches in their northern parts and descending branches in their southern parts.Eventually,the ASM strengthens,leading to a southern dry and northern wet pattern in East Asia and India.The AMV exerts a remote effect on the East Asian summer rainfall through an atmospheric teleconnection,and the TP serves as a booster of this remote effect.The warming of the North Atlantic（positive phase of AMV）enhances the Asian summer monsoon through a zonal Rossby wave train along the northern mid-latitudes,yielding an anomalous tripole rainfall pattern over East Asia.The enhanced warm and moist monsoon airflow converges and climbs up along the southern and eastern flanks of the TP,resulting in stronger latent heating over the TP than over other regions along the same latitude due to the orographic effect of the huge plateau.The enhanced TPHS in turn further strengthens the summer monsoon and the East Asian tripole rainfall pattern by exciting a downstream meridional wave train.Hence,the TP acts as a booster on the influence of AMV on East Asian summer monsoon and summer rainfall.