关键词: 青藏高原东部, 夏半年, 强降水事件, 气候特征

Abstract: Based on the daily precipitation data of 47 meteorological stations from May to September during 1963-2012 in the eastern Tibetan Plateau, the methods of linear trend analysis, polynomial curve fitting analysis, wavelet transform, inverse distance weighted interpolation method etc. are employed to analyze the temporal and spatial distribution of heavy precipitation, frequencies and relative intensity in nearly 50 years and applying R/S method to predict the heavy precipitation variation in future. According to the actual precipitation during summer half year in the eastern Tibetan Plateau, more than 25 mm of daily precipitation are used as the standard of heavy precipitation. The climatic characteristics of heavy precipitation events in the eastern Tibetan Plateau have an important influence on global climate change and in order to better contrast the internal differences of heavy precipitation over the eastern Tibetan Plateau, the study region was divided into five different natural zones. The results are as follows:(1) Heavy precipitation events often occurred in July and dominated by 1 d single-station in summer half year over the eastern Tibetan Plateau.(2)In recent 50 years, the heavy precipitation and frequencies showed weak increasing trend, the linear trend rate is 0.25 mm·(10a)^-1 and 0.01 d·(10a)^-1 respectively and they will be increasing in the future. In the five natural zones, the linear trend rate is different, only Naquyushu area showed a decreasing trend and the increasing trend is the most notable in the Chaidamu area.(3) Heavy precipitation and frequencies existed a decadal oscillation cycle with quasi 12 years, as well as, after the 1978, the heavy precipitation had inter-annual oscillation cycle with 3 years during summer half year over the eastern Tibetan Plateau.(4)During summer half year, the spatial distribution patterns of heavy precipitation and frequencies was very similar to each other, which decreased from southeast to northwest, its highest and lowest value occurred in the east Tibet-west Sichuan and Chaidamu area respectively.(5)The relative intensity of heavy precipitation increasing from south to north during the summer half year, among them, the relative intensity of Chaidamu area is the largest and the east Tibet-west Sichuan area is the least, so the relative intensity and heavy precipitation showed a reverse characteristic.(6)In the five natural zones, there are positive correlations between heavy precipitation, frequencies and total precipitation in the summer half year, the differences correlations in relative intensity and total precipitation in the summer half year still exist significantly. At the same time, the correlation between the three index and total precipitation during the summer year is the most significant in Chaidamu area. Through a series of analysis, the paper aims at providing some reference to climate change, ecological environment protection and disaster reduction. According to these conclusions, some predictive information of heavy precipitation events over the eastern Tibetan Plateau can be provided to the relevant apartments.

Key words: Eastern Tibetan Plateau, summer half year, heavy precipitation events, climatic characteristics