The Correlation Of Transition Time Among Different Isobaric Surfaces In East Asia And Its Impact On The Precipitation

Using the daily air temperature,geopotential height in the ERA-Interim data for 1979-2015 to calculate the tropospheric lapse rate(20°~50°N,70°~130°E),analyze its characteristic,The results show that:(1)The lapse rate changes with latitude,and it may results from the underlying surface,landform,the distribution of arid and humid region,moisture condensation.(2)The lapse rate changes with longitude,it is high in the west of China and low in east of China.And there are sudden change in 105°E and 120°E,which is relative to the three steps of topography and the distribution of arid and humid region.(3)The lapse rate vary from season to season,in general,their fluctuation in summer and fall are smaller than in spring and winter,also the fluctuation in winter is biggest in the four season.(4)The interannual change of lapse rates in different level are different,which is relative to the global climate change.Calculating the zonal thermal at 4 pressure levels in troposphere over subtropical East Asia(20°~35°N),and the linear trend analysis,Morlet wavelet analysis methods are applied to analyze their interannual transition trend and periodic variation.Base on the above analysis,the relationship among these pressure levels' transition is discussed in this research.The results show that:(1)The transition from winter status to summer status in 850 hPa occurs at about the 18 th pentad,which is the earliest among troposphere,and it occurs at about 22 nd in 500 hPa,which is the latest among troposphere.The transition from summer status to winter status change with their levels,the higher level,the later transition occurrence.(2)The latitude leads to the different transition occurrence,In 200 hPa the transition from winter status to summer status is earliest in 30°N,in500 hPa the transition time's difference is not obvious,in 850 hPa the transition time is latest in 25°N and 30°N,and advance gradually in low and high latitude,in 1000 hPa the transition time advance with latitude rise.the transition from summer status to winter status is latest in 25-30°N and advances in low latitude and high latitude;in 500 hPa the transition advances with the latitude rise;in 850 hPa and 1000 hPa the transition change are not obvious(3)The troposphere's(850hPa,500 hPa,200hPa)transition from winter status to summer status show an advance trend,and summer status to winter status show an delay trend,which relates to the global climate change and its different impact on different level.(4)The wavelet verifies that the transition from winter status to summer status in200hPa?500hPa?850hPa?1000hPa fluctuate primarily with an 13 a,13a,4a,16 a cycle respectively and fluctuate primarily with an 16 a,8a,16 a,11a cycle respectively from summer status to winter status,what is more,4 level pressure all have the high-frequency phenomenon.Calculating the correlation coefficient between lapse rate and the same term's precipitation,the grey correlation coefficient between transition time series and the same term lapse rate.The results show that:(1)In inerannual change scale,the lapse rate between 500 hPa and 850 hPa,850hPa and1000 hPa have great indexicality to the southwest in China,the lapse rate in summer has great indexicality to the area that is affected to summer monsoon,such as northeast,south and north China,because of the winter monsoon's character and the influence of landform,the correlation coefficient is not obvious over the China.(2)The earlier(later)transition time from summer status to the winter status,the less(larger)lapse rate over China.