The Temporal And Spatial Characteristics Of Heat Fluxes In The East China Sea And Their Association With Summer Rainfall In East China

Based on the OAflux3, the NCEP/NCAR reanalysis data for long time series and theobserved data of precipitation at 120 observational stations of Eastern China, the temporaland spatial characteristics of sea-air heat fluxes in the East China Sea and their associationwith summer rainfall in East China are analyzed by using the empirical orthogonal function(EOF) and the linear regression analysis methods. The analyzed results show that :(1)We known that the heat fluxes exhibit large year-to-year variations in the EastChina Sea, Kuroshio and its Extension in the South of Japan, and latent heat flux had beenincreasing from 1958 to 2008 but changed from negative to positive anomaly in 1980s. Thespatial pattern of EOF1 mode of summer latent heat flux displays strong signal in the Yellowsea, East China Sea, Taiwan Strait and the regional parts of northern South China Sea.Furthermore, the corresponding time coefficient of EOF1 (PC1) indicates significantinter-annual variation and a climatic shift around 1997.(2)Changes in sensible heat flux is smaller than latent heat flux. In Spring, Autumnand Winter, sensible heat flux changed significantly in the Yellow sea, East China Sea,Kuroshio and its Extension in the South of Japan ,and it displays strong signal in the Yellowsea, parts of East China Sea, and the regional parts of south of Japan, that is similar to latentheat flux.(3)As shown in all EOF1 modes, there exists an in-phase variation betweenatmospheric moisture transport and summer rainfall in eastern China , and there is aanti-phase variation between meridional circulation and summer rainfall in eastern China.Theabnormal change of latent heat flux in summer has a close relation with the change ofsummer rainfall and meridional circulation. In contrast to the situation in North China andNortheast China, as latent heat flux anomaly in East China Sea is positive, the meridionalcirculation will be manifested as updraft anomaly in the regions of Huang-Huai valley andSouth China, which may result in more summer rainfall.(4)In East China sea and its adjacent waters, the summer latent heat flux has a climatic jump in 1997, and has been increasing after 1997. This is likely to be one ofimportant factors for the abnormal reducing of summer rainfall in North China. Moreover,itis because that the summer latent heat flux has affection on moisture convergence ,which isachieved by meridional circulation in EastAsia.