Study On Ocean-atmosphere Interaction In The Mid-latitudes Over The Northwest Pacific

Generally speaking, there are two times seasonal movement of the subtropical high over the Northwestern Pacific, The subtropic high ridge locates the north 15oN in winter. With the summer coming, the ridge of subtropical high north jump to 20o～30oN in the middle ten days of June. But at the same time in 2005, The subtropic high ridge position is abnormal, which locates the north 12o～17oN; As the same time,In a larger sea surface of Pacific at the south of Japan,cold water formed and maintained until 2005.6.26.As a result of the subtropic high ridge locates more to south compare with normal years, the mold rain mostly gone in lower reaches of Yangtze river. So ,people focus attention upon to find out the reasons which cause the subtropical high's movement abnormal . To study the relationship between mid-latitudes Pacific SSTA and the subtropical high is beneficial to improve the precision of subtropical high prediction.By using the NOAA weekly mean data of Sea Surface Temperature and NCEP2 Geopotential Height daily mean data (1982～2005). we also used the latent heat daily data,sensible heat daily data,relative humidity data and OLR daily data from NCEP-DOE Reanalysis2 which formed as 2.5-degree latitude x 2.5-degree longitude global grid with 144x73 points(1982～2005). The data of subtropic high ridge offered by Bational Climate Center (NCC) .With singular value decomposition (SVD) analysis, we studied key region of ocean-atmosphere interaction in the mid-latitudes in the Pacific. Second, by using wavelet analysis to study the character of the key regions of SST.Moreover the correlation analysis can help us to understand the reason of the cold water formed and the physical process of ocean-atmosphere interaction in the mid-latitudes in the Pacific.There are three mostly SVD modes which contribution reach to 70%,So the three mostly modes can reflect the mostly structure in the key region. With singular value decomposition (SVD) analysis,we studied that the key region of ocean-atmosphere interaction in the mid-latitudes in the Pacific locates in 20o～135oN,120o～165oE;Different kinds of joint effects in the SST anomalies of key regions, for example , Geopotential Height abnormal,cold air north of China,East Asian Summer monsoon,convection activity,subtropical high and so on ,all of them can cause the SST abnormal. When the SST of key region is cold (warm) , where the air pressure will be down (up), so the cyclone (anticyclone) formed. convection activity accelerate the latent heat release in the key region ,which also lead the subtropic high stay more to south in 2005.6. In other word, the subtropic high ridge locates more to south promoted the convection activity in this area.So a positive feedback formed.The innovation of this study is that by using the SVD, the key region of ocean-atmosphere interaction in the mid-latitudes in the Pacific be located, and the reasons have be discoverd that how the cold water formed in the mid-latitudes in the Pacific,and the effect to Geopotential Height and subtropical high .