Water Vapor Transport Over The Tibetan Plateau In Summer And Its Relationship With The Autumn Arctic Sea Ice Last Year

Based on the daily data of MERRA-2 during 1980-2017,the climatological characteristics and anomaly characteristics of stationary,transient,mean flow and eddy transport and divergence of water vapor in summer over the Tibetan Plateau(TP)were revealed by means of Lorenz circulation decomposition method.Then,based on the Arctic sea ice concentration(SIC)data from the Met Office Hadley Center during 1979-2016,the correlation analysis between autumn Arctic sea ice and water vapor transport in the subsequent summer over the TP were clarified by means of singular value decomposition,correlation analysis,regression analysis,composite analysis and sliding correlation.The conclusions were as follows:(1)There was eastward total zonal water vapor transport over the TP.The magnitude of transient transport(?)was one order smaller than stationary transport(?).However,the(?)in the latitudinal range of the plateau was much larger than that in other latitudes,showing strong westward transport.The magnitude of the low frequency component(with periods longer than 10 days)of(?)was one order larger than the high frequency component(with periods less than 10 days),which played the dominant role.The stationary transport of the zonal mean water vapor by zonal mean flow(?)and the stationary transport of the zonal deviations of water vapor by zonal mean flow(?)dominated(?).The transient transport of the zonal deviations of water vapor by zonal mean flow(?)dominated(?).Note that(?)and(?)was related to large zonal asymmetry of specific humidity and was a result of the Asian water tower over the TP in summer.(2)There were poleward total meridional water vapor transport in the troposphere but equatorward transport in the stratosphere over the TP.The total meridional water vapor transport was dominated by the stationary transport(?)in tropics but dominated by the transient transport(?)in extra-tropics.The magnitude of high frequency component of transient transport was twice of the low frequency component.The stationary transport of the zonal mean water vapor by eddies(?)controlled(?)in the stratosphere,which was related to the meridional wind distribution in the mid-Pacific trough and the east and west sides of South Asia High.The stationary transport of the zonal deviations of water vapor by eddies(?)restrained(?)in the troposphere,which was related to the high specific humidity distribution over the TP.The transient transport of the zonal deviations of water vapor by eddies(?)was the main part of(?),which was the result of combined action of specific humidity and meridional wind.(3)The transport of stationary water vapor field by transient wind field was the main transport process and controlled the distribution and intensity of the total water vapor transport in the anomalous field of water vapor flux,which was the result that the intensity of transient wind field was greater than that of transient water vapor field.(4)The declining autumn SIC in the Kara-Laptev Seas corresponded to the westward(eastward)water vapor transport anomaly in the southwest(northeast)side of the TP and the southward water vapor transport anomaly over the TP in the subsequent summer at 500 h Pa.With the increase of altitude,the corresponding abnormal mode of water vapor transport at 200 h Pa inclined from southeast to northwest.The declining autumn SIC was weakly(strongly)correlated with the zonal water vapor transport at 500 h Pa before(after)2004 in the subsequent summer over the TP.The declining autumn SIC was strongly correlated with the zonal water vapor transport at 200 h Pa before 1990 and after 2004 in the subsequent summer over the TP.The declining autumn SIC was strongly correlated with the meridional water vapor transport at 500 h Pa in the early 1990 s and after 1999 in the subsequent summer over the TP.The declining autumn SIC was strongly correlated with the meridional water vapor transport at 200 h Pa in the subsequent summer over the TP.