2006年西南地区异常高温及其成因分析

Analysis of abnormal high temperature in Southwest China in 2006

2006年我国西南地区发生了严重的高温天气,筛选了1948年—2006年西南地区7、8月日平均气温持续3天及其以上高于25.5℃的高温时段,分析了西南地区高温变化的特征。结果表明:20世纪90年代以后,高温时段出现得更频繁,尤其在2006年西南地区夏季月平均气温持续偏高、高温出现时间早、高温影响范围广、高温日数异常偏多。分析了西南地区盛夏气温的年代际变化,并进行了滤波,发现西南地区的气温有20年左右的周期,2006年处于波峰。还分析了影响西南地区异常高温的因素,副热带高压的脊线西升、北抬导致了西南地区异常高温的产生。大陆高压中心位置比平均偏东偏北亦是造成西南地区高温的原因。另外青藏高原积雪深度和积雪日数与西南地区异常增温有一定的关系。通过分析高温前冬季和春季积雪分布,发现二者之间有明显的负相关,春季积雪异常对西南高温有较大的影响。

An abnormal high temperature took place in eastern Sichuan and Chongqing in 2006.The high-temperature periods from 1948 to 2006 are screened with temperature greater than 25.5 degrees Centigrade and at least lasting for three days in July and August.The results show that the frequency of high temperature is higher since 1990s such as in 2002,2003 and 2006.The high temperature in 2006 is studied.The monthly mean temperature is high,which occurs earlier and wider with much more days of high temperature.It has quasi-20-year period and in 2006 it attains the peak.The westward,northward advance of the Subtropical High results in the high temperature.That the center of the Continental High lies northward and eastward is one of these reasons.Moreover,the snow depth and snow cover days over the Qinghai-Tibet Plateau,especially in spring,can also influence the temperature in southwest China.There is an obvious negative correlation between the snow cover and the temperature in southwest China.