Characteristics Of The Extreme High Temperature In Summer In East China And Relationship With The Tibetan Plateau Warming

Based on the daily maximum temperature data from 449 stations over Eastern China (east of 100°E) during 1960-2012, the spatial and temporal variations of extreme high temperature days (daily maximum temperature exceeding the 95th percentile) and continuous high temperature days (the maximum period of at least 3 consecutive days with daily maximum temperature higher than the 90th percentile) in summer were investigated. Both the extreme high temperature days and continuous high temperature days increase significantly in Northern China (north of the Yellow River), Southern China and around Hangzhou Bay area, while consistently decrease in the central China between the Yangtze River and Yellow River. The two indices indicated opposite tendencies in lower reaches of the Yangtze River, namely, the extreme high temperature days increased significantly, but the continuous high temperature days declined. Considering the seasonal characteristics, extreme high temperature days and continuous high temperature days mainly concentrated from June to July and July to August in north and south of the Huaihe river, respectively. Each region of the two indices demonstrated significantly negative correlation with precipitation days, but there was obvious difference between those over the north China and the south China. Significantly negative correlation were found between the two high temperature indices and precipitation days in interannual variability and on decadal scale in Northern China, but merely on interannual scale over central regions. The correlations between continuous high temperature days and precipitation days in HangzhouBay and south China were found only on decadal scale. The positive trends of the extreme high temperature events are closely associated with the decreasing number of rainy days and precipitation in the North China. Changes of extreme high temperature days and continuous days of high temperature in the Southeast China are related to the significantly westward extending of the Northwestern Pacific subtropical high.Obviously rising temperature was observatived over the Tibetan Plateau in the past 50 years. The regional average temperature was rising at the rate of 0.24 ℃/per decade, while the magnitude of warming rate was larger after 1980s, which was 0.38 ℃/per decade.The warming in the northeast of Tibetan Plateau was more obviously. There was significantly negative correlation between the temperature change in eastern Tibetan Plateau and the rainy days in eastern China, especially in the northern China.Two Rossby wave trains in high and low layer are excited due to TP warming. Under the abnormal anticyclone controlling, the rainy days in the northern China reduced, so that extreme high temperature increasing in the northern China. The result in this paper verified the numerical model results in the paper of Wang et al.(2008).