长江三峡库区极端大雾天气的气候变化特征

为了进一步认识长江三峡库区大雾天气特征，采用线性趋势估计和Molet小波分析方法，研究了库区持续12 h以上和连续3 d以上极端大雾天气气候变化特征，探讨了库区蓄水后大雾天气气候变化的原因。结果表明：三峡库区年平均雾日数呈弱的下降趋势，存在准8、18、32 a的年代际周期振荡。持续12 h以上和连续3 d以上大雾天气有明显增加趋势，分别存在准10、17、32 a和准12、32 a的年代际周期振荡。在蓄水后，库区西段年平均雾日数明显减少、东段略有增加，持续12 h以上大雾年平均日数变化不大，连续3 d以上大雾年平均日数明显减少。库区年平均雾日数的总体减少在很大程度上是受全球气候变暖以及城市化共同影响的结果，没有证据说明三峡库区蓄水对大雾天气有明显影响。

AN ANALYSIS OF CLIMATIC CHARACTERISTICS OF EXTREME FOG IN THE REGION AROUND THE THREE GORGES RESERVOIR

In order to further understanding the characteristics of fog in the region around the Three Gorges Reservoir,this paper studied the climate changes of extreme fog which last 12 hours and 3 days,discussed the possible reasons of the fog changing by using linear trend estimates and moletwavelet analysis.The results show that,the annual mean fog days in the region around the Three Gorges Reservoir shows a weak downward trend and there are decadal oscillations of 8,18 and 32 years.Extreme fog lasting 12 hours and 3 days shows a significant increasing trend,and there are decadal oscillations of 10,17,32 years and decadal oscillations of 12,32 years,respectively.The annual mean fog days in west section of the Three Gorges Reservoir significantly reduced,but increased in east section after impoundment.The annual mean fog days of extreme fog lasting 12 hours changes little after impoundment,but the annual mean fog days of extreme fog lasting 3 days significantly reduced after impoundment.The reduction of foggy days in Three Gorges area is affected by the results of global warming and urbanization,and there is no evidence that the impoundment in three Gorges area have influence on the fog.