近55年来云南区域性干旱事件的分布特征和变化趋势研究

Studies on Distribution Characteristics and Variation Trend of the Regional Drought Events over Yunnan in Recent 55 Years

本文利用一种简化的区域性干旱事件识别方法,对近55年来云南区域性干旱事件进行了识别,在此基础上,选取区域性干旱事件的持续天数、影响站点数、平均强度、累积强度和极端最大强度这5个单一事件评价指标,构建了云南区域性干旱的综合评估模型,确定干旱等级划分标准。进一步分析表明,云南区域性干旱的发生频次、累积强度和累积影响站次均呈现上升趋势;云南在12、1和3月干旱发生最多,7、8月干旱发生最少;干旱持续天数集中在15～45 d,最长的可达222d;云南多发全省性的干旱且旱情偏重。云南中部区域干旱偏多、偏重发生;在严重的干旱事件中,中部型发生频次最多。

In this paper,the cluster regional drought events in Yunnan from 1961 to 2015 are examined by using a simplified identifying method. Based on the identified drought events, we construct a comprehensive evaluation model of the regional drought event to classify the drought grade using lasting days, stations, the average strength, accumulated strength and extreme strength of drought events. The results further show that frequency, accumulated intensity and accumulated impact of regional droughts display an increasing trend in Yunnan. Regional drought events frequently occur in December, January and March,but less in July and August. The drought events mainly persist 15-45 d, with the longest up to 222 d.Droughts often spread over whole Yunnan Province and influences seriously. In central Yunnan, drought is more frequent and serious. Especially, among the severe drought events, the middle pattern drought occurs most frequently.