近几十年三峡库区主要气象灾害变化趋势

利用三峡库区33站1961～2006年逐日降水量、平均气温、最高气温、雾、雷暴资料，分析了库区干旱、洪涝、连阴雨、高温、雾、雷暴主要气象灾害的变化趋势。统计结果表明：近46年来，三峡库区平均年干旱日数呈不明显的增加趋势，春、夏、冬季干旱日数的年际间基本没有变化趋势，但秋季干旱日数年际间有明显的增多趋势，增多速率为41 d/10 a；春、夏季雨涝日数变化趋势不明显，秋季雨涝日数有微弱的减少趋势；三峡库区年平均连阴雨过程次数有微弱的减少趋势，连阴雨日数的减少趋势较明显；近34年三峡库区年雷暴日数呈明显减少趋势，减少速度为29 d/10 a；库区平均年雾日数没有明显变化趋势,但1999年以来减少趋势明显；近46年三峡库区平均年高温日数、危害性高温日数有微弱的减少趋势，平均年极端最高气温均没有明显变化趋势。

CHANGING TRENDS OF MAJOR METEOROLOGICAL DISASTERS IN RECENT DECADES OVER THREE GORGES RESERVOIR AREA

Based on the daily observational data of precipitation,temperature and weather phenomena of 33 stations over Three Gorges Reservoir area during the period 1961 to 2006,the linear trends of some major meteorological disasters like drought,flood,continuous rain,heat wave,fog,thunderstorm were analyzed.It was found that the average annual drought days have a slight increasing trend in the Three Gorges Reservoir area. There was no significant change in seasonal drought days of spring,summer and winter,while an upward trend in autumn drought days at a rate of 4.1 d/10 a was found.The analysis of precipitation showed that the presence of flood days decreased slightly in autumn,while the annual continuous rainy days decreased significantly and yearly thunderstorm days had decreased at a rate of 29 d/10 a.The foggy days in Three Gorges Reservoir area had no obvious change as a whole,while significant decrease trend was found since 1999.Average extreme high temperatures had no upward or downward trend,but heat wave days had a slight downward trend.