基于不同干旱指数鲁中地区干旱变化规律研究

Research on the variation of drought in the middle of Shandong province based on different drought indices

利用1980—2014年鲁中地区8个代表气象站逐日的气象观测资料,采用累积频率法对5种干旱指数的阈值进行修正,分析了鲁中地区干旱的时空变化特征,并研究不同干旱指数在鲁中地区的适用性。结果表明:1980—2014年鲁中地区5种干旱指数计算的年平均干旱日数为92—106 d,干旱中心位于鲁中中部地区,干旱日数随时间变化均呈减少趋势,减少幅度为2—6 d/10 a,其中综合气象干旱指数对干旱持续时间长和干旱程度较重年份的监测效果较好;鲁中地区四季干旱日数监测效果较好的干旱指数不同,春季、夏季和冬季干旱日数随时间呈减少的趋势,四季干旱日数的空间变化规律不一致;鲁中地区干旱日数最多和最少的月份分别为5月、8月,干旱日数年变化呈近余弦的变化规律,鲁中地区不同月份干旱日数监测适用的干旱指数不同。

Based on the daily meteorological data from 8 representative weather stations in the middle of Shandong province during 1980 to 2014,a cumulative frequency method was adopted to correct the thresholds of five drought indices. The temporal-spatial variation characteristics of drought and the applicability of each drought index in the studied area were analyzed. The results show that mean annual drought days calculated using the five indexes are about 92 to 106 days. It has a decreasing trend with decadal decreasing rates ranging between 2 and 6 days per decade. The center of drought area is located in the middle part of the central Shandong province. The compound drought index is the best indicator among the five indices for recognizing severe and long-duration drought years. The suitable drought index varies with seasons in the research area. Drought days in spring, summer and winter are declining during the 35 years and spatial change characteristics of drought days are different among four seasons. In addition, the most and the least droughts occurs respectively in May and August. Annual pattern of monthly drought days appears to be an approximate cosine rule. Besides, the drought indices which work most effectively in recognizing drought days vary from one month to another.