基于Z指数和云模型的川中丘陵区干旱分布研究

Analysis of distribution characteristic of drought in Sichuan hilly area based on drought index and cloud model

Z指数法是气象干旱评价中一种较为有效的方法,它以降水量为主要评价指标。但由于降水量并不完全符合正态分布,且依据Z指数法评价的旱涝等级标准受主观影响大,简单的数值比较不能完全客观揭示干旱的时空分布特征。因此,可将具有模糊隶属度分析优势的云模型理论和Z指数法相结合,共同揭示干旱的时空分布特征。以川中丘陵区22个站点近60 a的干旱变化为例的实证分析结果表明,干旱的类型占比、时间分布特征、Z指数序列趋势分析均可准确刻画研究区干旱的实际变化规律,该研究方法是可行的。研究方法可为今后气象干旱评价研究提供借鉴。

Z index, an effective way for meteorological drought evaluation, adopts precipitation as a main index. However, the precipitation does not strictly follow normal distribution, and also the drought grade evaluated by Z index is under subjective influ-ence, so the simple value comparison can not reveal the drought distribution law objectively. For this reason, the cloud model theory with fuzzy membership analysis is combined with Z index analysis to reveal the spatial and temporal distribution of drought. The practical analysis results from drought change in 22 sites of Sichuan hilly area for nearly 60 years show that the drought type proportion, time series distribution and Z index series trend analysis can accurately depict the actual drought variation in the study area. The research method is feasible, which provides a better reference for the future evaluation of meteorological drought.