【摘要】 黄土高原生态环境脆弱,极端气候频发,越来越多的影响到人类的生产生活。通过基于138个气象站点观测资料,利用一元线性方程和Mann-Kendall法分析了黄土高原地区27个极端气候指数的时空变化,得到以下主要结论:(1)极端气温指数中霜冻日数、冰冻日数、日最低气温的极高值和冷持续日数在逐渐减少,生长季长度、夏季日数,热夜日数、日最高气温的极高值、暖持续日数在逐渐增加。(2)极端气温指数中冷昼日数、冷夜日数、日最低气温极低值、日最高气温极高值、气温日较差在子区域与全区变化趋势存在不同,主要表现在黄土塬区、黄土峁状丘陵区和石质山地区。(3)极端降水指数变化趋势平缓,与多年均值接近。在空间分布上,除极强降水量、强降水量和年均雨日降水强度在各子区域上与全区变化趋势一致外,其余指数在各子区域上与全区变化趋势存在不同,主要表现在黄土塬和黄土梁状丘陵区。(4)多数极端气温指数的突变主要发生在1980—1985年和2010—2015年;多数极端降水指数的突变主要发生在1985—1990年和2010—2015年。更多还原

【Abstract】 Loess Plateau is the central region of China’s mainland and its fragile ecological environment and frequent extreme climate greatly impact human production and life. Based on the 138 meteorological site observation data,using the method of monadic linear equation and Mann-Kendall for 27 of the Loess Plateau region’s spatial and temporal variations of extreme climate index not only help promote the Loess Plateau area’s ecological environment protection and soil and water conservation management, but also strongly provide a decision support for regional sustainable development in the Loess Plateau. By studying the trends of extreme climate index and mutation, the following conclusions are generated:(1) The Loess plateau of extreme temperature index of frost days(FD0), ice days(ID0), monthly maximum value of daily minimum temperature(TNx), and cold spell duration indicator(CSDI)are decreasing gradually; Growing season length(GSL), summer days(SU25), tropical nights(TR20), monthly maximum value of daily maximum temperature(TXx), and warm spell duration indicator(WSDI) are increasing continuously, while the rest of the index change vary more gently. In general, the cold index and the warm index of the Loess Plateau’s extreme temperature index are decreasing gradually.(2) There are spatial differences in the extreme temperature indexes. In addition to the indexes consistent with the changes of the whole region, cool days(TX10P), cool nights(TN10P), monthly minimum value of daily maximum temp(TXn), monthly maximum value of daily maximum temp(TXx), and diurnal temperature range(DTR) are different in sub-regions and the whole region,which are mainly manifested in the Loess tableland, hilly Loess, and rocky mountain areas.(3) The variation trend of extreme precipitation index is flat and close to the multi-year average. Simple daily intensity index(SDII) and very wet days(R95 p) showed an upward trend, while consecutive dry days(CDD), extremely wet days(R99p) and consecutive wet days(CWD) showed a downward trend. However, the change trend was not obvious on the whole. In terms of spatial distribution, except for wet days(R99p), very wet days(R95p), simple daily intensity index(SDII),strong precipitation, and annual average daily precipitation intensity are consistent with the variation trend of the whole region in each sub-region. Other indexes are different from the variation trend of the whole region in each subregion and are mainly manifested in Loess tableland and girder hills.(4) Most of the abrupt transitions of extreme temperature indexes occurred in 1980—1985 and 2010—2015, while most of the abrupt changes in the extreme precipitation index occurred from 1985 to 1990 and from 2010 to 2015. Comparing the abrupt transition nodes of the two, the abrupt transition time node of the extreme temperature index is relatively earlier than that of the extreme precipitation index.更多还原