北京冷暖冬年环流特征及其与前期北太平洋海温的关系

利用1951～2005年北京气温资料和北半球500 hPa高度及北太平洋海温资料,分析了北京冬季气温的异常变化及其环流特征以及与前期北太平洋海温的关系.20世纪50年代以来北京冬季气温变化具有50、60年代低,自70年代开始逐年代升高的趋势,90年代至今处于高温时期.北京冷暖冬年,其同期和前期500 hPa环流特征具有明显不同;前期北半球副高及有关副高单体其强弱变化,对北京冬季气温有很好的指示性.前期春季西风漂流区海温和南赤道海流区海温异常变化可作为北京冬季异常冷暖的前兆信号.前期春季南赤道海流区海温异常偏高时,有利于北京暖冬年环流形势的形成.前期春季西风漂流区海温异常偏低时,有利于北京冷冬年环流形势的形成.

Relation between Circulation Characteristics in Beijing and Antecedent SST in North Paci ficin Cold/Warm Winter Years

The abnormality of temperature in Beijing, the corresponding atmospheric circulation characteristics, and the relation with the antecedent SST over Northern Pacific are analyzed with the data of temperature in Beijing, 500 hPa geopotential heights over the Northern Hemisphere, sea level pressure and sea surface temperature (SST) over the North Pacific from 1951 to 2005. The winter temperature in Beijing had the following variation: lower in the 1950s and 1960s, gradually increasing since the 1970s, and remained high since the 1990s. The 500 hPa circulation characteristics in the previous and present periods are quite different. The intensities of the Northern Hemispheric Subtropical High and the relevant subtropical high cells can well reflect the winter temperature in Beijing. The abnormal SST variations on the westerly driftage area and the Southern equatorial ocean current area in the previous spring can be a signal to the abnormal low (high) temperature in Beijing. When SST on the Southern equatorial ocean current area in the previous spring is abnormally high, it is advantageous to the build up of the favorable circulation for Beijing warm winter. When SST in the westerly driftage area in previous spring is abnormally low, it is favorable to the formation of the cold winter circulation pattern in Beijing.