The Effect Of Meridional Thermal Difference In East Sea To The Climate Change Of China's Land In Summer

The effect of meridional thermal difference in East Sea to the climate change of China's Land in summer is mainly discussed in this paper.Based on the different resolution between WRF model result and FNL data, and case simulation of different seasons, this article discussed the impact of sub-synoptic scale system to water vapor transport in East China Coast. The results show that the sub-synoptic scale system had strong influence to local wind field in the lower level. In the winter and summer case, it showed that the sub-synoptic scale system made the background wind field strengthened; The impact to water vapor transport has a strong seasonal dependence. In the winter example, the impact is the most significant, and secondly in the spring case. Sub-synoptic scale system is significantly affected by the terrain, which could strengthen the role of sub-synoptic scale system.In this article, the difference of heat content anomaly between the Kuroshio sea area and the Yellow sea area are used to on behalf of the intensity of meridional thermal difference (MTD) in East China Coast. The study of influence of summer (mainly in July) MTD is based on the data of NCEP and WRF model. We found that the intensity of MTD has an increased trend from 1979 to 2006. In the year when MTD is stronger, there is anomaly northeast wind over the Yellow Sea; and in the year when MTD is weaker, there is anomaly southwest wind over the East China Sea, and what's more, there is good correspondence in theωfield. And in the MTD strong year, in the anomaly Geo-potential height field, the west pacific sub-tropical high is weaker. The time series correlation analysis between the intensity of summer MTD and Nan Jing's anomaly air temperature in July from 1979 to 2006 shows that there is a significant negative correlation between them, which means Nan Jing's anomaly air temperature will be lower in the year when MTD is stronger. That's because there is anomaly northeast wind over the Yellow Sea, which weaken the summer monsoon over China Southeast. And at the same time, the west pacific sub-tropical high is weaker. The enhancement of MTD in summer will weaken the southwest summer monsoon in South China and decreased the water vapor and heat transport to the East, decreased the transport to the high latitude from South China Sea. The SST sensitive test and ideal test to the East China Coast found that there exits anomaly northeast wind over Yangtze River Estuary. That because there is strong SST gradient from south area to north area, and there will be updraft in the south area and downdraft in the north area. And According to the Dyne principle of compensation, there will be northerly wind at this time, which will change into northeast wind under the effect of Coriolis force.