基于模糊C均值聚类法的河南省近57年干旱特征分析

根据河南省1960-2017年19个气象站的逐日降雨数据计算标准化降水指数(SPI),结合模糊C均值聚类法、小波分析,从月、年际和周期维度上研究近57年来河南省干旱的时空变化特征。结果表明:所有气象站点可以分成3个区域,分别为豫东南、豫北、豫西地区;全区在1966、1986、1997年发生持续干旱,豫东南持续干旱时间最长为10个月且在夏季易旱,豫北持续干旱时间最长为9个月且易发生特旱,豫西持续干旱时间段最多但尺度最长为7个月;干旱频率主要分布在豫北,豫西次之,豫东南最小,但干旱频率都在30%以上,且20世纪90年代后干旱频率在各区之间分布比较均匀;豫东南、豫北、豫西分别呈现23～25、20～22、15～17 a易干旱的主周期。

Analysis of drought characteristics in Henan Province in the latest 57 years based on fuzzy C-means clustering

Based on the daily precipitation data of 19 meteorological stations in Henan Province of the latest 57 years from 1960 to 2017, the standardized precipitation index (SPI) was calculated. The spatial and temporal characteristics of drought in Henan Province were studied in terms of monthly, interannual and periodic dimensions by the fuzzy C-means clustering and wavelet analysis. The results showed that all meteorological stations could be divided into three regions: southeastern Henan, northern Henan and western Henan. There was a continuous drought in 1966, 1986 and 1997 for the whole Henan Province. The longest continuous drought period in southeastern Henan was 10 months and drought prone in summer. The longest continuous drought period in northern Henan was 9 months and it was prone to severe drought. The continuous drought periods in western Henan was the most, but the longest scale was 7 months. Drought frequency was mainly distributed in northern Henan, followed by western Henan, and the least in southeastern Henan, but it was more than 30% and more uniform among regions after the 1990s. The main cycle of 23~25, 20~22 and 15~17 years were drought prone in southeast Henan, northern Henan and western Henan, respectively.