Teleconnection of Sea Surface Latent Heat and Water vapor transport in East-Asia with Summer Rainfall Anomaly over Chinese Mainland

Abstract

Based on NCEP/NCAR reanalysis data and rainfall observation from 160 stations over Chinese mainland, optimum teleconnection patterns(the first coupled modes) of the pre-seasons (winter and spring) and homochronous (summer) sea surface latent heat flux (LHF) and watervapor flux (WVF) anomalies in East Asia with the summer rainfall anomaly over Chinese mainland were provided by applying SVD method. Thespatio-temporal characters of the optimum coupled fields and intrinsic relations in them were investigated. The results showed that, the key searegions of the LHF variation teleconnected to rainfall anomaly were mostly in the Kuroshio area and the Bay of Bengal (positive correlation) andthe zone of the North equatorial current (negative correlation) in preceding winter, and in Indian-Pacific warm pool region and other sea 1areas alternatedwith band-like fields of positive and negative LHF anomalies in preceding spring and homochronous summer. They were all distinctly associatedwith a dipole distribution of rainfall anomaly in eastern China, and that significant regions of the rainfall variation were the South Chinaand its anti-phased regions of the North China and the east of Southwest China, especially in spring and summer of the same year. There existed asignificant 2~7 year oscillation and an evident tendency in the variations of optimum coupling modes and all modes experienced a distinct climateshift in early 1970s. As to the WVF, the key sea regions of the WVF associated with the summer rainfall anomalies were mainly in South ChinaSea, the Bay of Bengal and the area of Kuroshio in East China Sea, mostly corresponding to the summer rainfall variation in spring and summerof the same year with the significant regions of the middle and lower reaches of Yangtze River and the out-of-phase counter-regions of the NorthChina and the east of Southwest China. The optimum coupling modes are striking of 2 to 8 year inter-annual variations. Except for pre-winter,those modes present obvious trends with a distinct climate shift in early 1980s. This paper suggests that the formation and its durative and seasonalevolutions of spatio-temporal configuration of the anomalous latent heat and water vapor transport over East-Asia is an important premise to theprecipitation anomalies over Chinese mainland.