基于SPI指数的近50年重庆地区干旱时空分布特征

目的]揭示重庆地区年和季度干旱发生的频率和强度的演变特征,为该区应对干旱灾害,制定针对性减灾措施提供科学依据和参考。方法]基于重庆地区34个气象观测站1964—2011年逐月降水数据,采用标准化降水指数(SPI)干旱指标方法进行研究。结果]干旱强度频率方面,重庆地区干旱发生的频率具有较明显的区域性和季节性;其中年、春、夏和冬季干旱发生频率相差不大,在25.9%~35.1%范围,秋季的发生频率范围幅度较大,介于16.7%~40.0%之间。干旱强度方面,在年和季节尺度上整体呈现一定的增加趋势,其中秋季和年度相对趋势更明显,近50a研究区年度和四季主要以轻旱和中旱为主,整体上夏季和秋季干旱强度比另外两个季度和年度表现更强一些。结论]标准化降水指数(SPI)适用于重庆地区,可以作为气候变化的监测指标;重庆地区干旱发生的频率具有较明显的区域性和季节性。

Temporal and Spatial Patterns of Droughts in Recent 50 Years of Chongqing City Based on Standardied Precipitation Index

Objective] The evolution of drought frequency and intensity was demonstrated yearly and quarterly in Chongqing City to provide scientific basis and reference for drought mitigation. Methods] Standardized precipitation index(SPI) drought index method was used, and the monthly precipitation data collected from 34 meteorological stations in 1964-2011 were dealt. Results] Frequency of drought had obvious regional and seasonal traits. The seasonal frequency of droughts varied differently. In spring, summer and winter, it had a range of 25.9%~35.1%; In fall, it had a big range from 16.7% to 40.0%. Either for yearly drought intensity or seasonal intensity, they both had an overall increasing trend, among which, annual drought intensity and the autumn one were more obvious. In the past 50 years, the study area was prevailed by intensity grades of mild drought and drought, either counted by years or by seasons. Drought occurred in summer and autumn were more severe than that in other seasons and in a whole year. Conclusion] Standardized precipitation index(SPI) can be used as indicators for monitoring the climate change of Chongqing City. The frequency of drought in Chongqing City has obvious regional and seasonal traits.