冬季北太平洋爆发性气旋的天气气候特征

本文利用1975—1984年12—2月北太平洋爆发性温带气旋资料以及500 hPa天气图，概括出气旋爆发式加强前12小时五种环流型，即北美高压型（NAH）、东太平洋高压型（EPH）、中太平洋高压型（MPH）、白令海阻高型（BBH）、太平洋低压型（PL）。以NAH型和EPH型出现的机会最多，稳定时间最长，并且在这两种天气形势下气旋最易发展。另外本文还分析了气旋爆发后的路径趋势，指出在形势稳定期，气旋爆发后的路径亦稳定；在形势调整期，气旋后期路径随太平洋长波系统的演变而变化。

Synoptic Climatological Characteristics of Explosive Cyclones over North Pacific in Winter

Based on analysis of 500 hPa synoptic maps associated with explosive extratropical cyclone activity over northwest Pacific in winter (from Dec. to Feb.) of 1975—1984, five synoptic patterns of extratropical cyclone development have been summarized in this paper, which are: North America High pattern (NAH), East Pacific High pattern (EPH), Mid Pacific High pattern (MPH), Berling Sea Blocking High pattern (BBH) and Pacific Low pattern (PL). The NAH and EPH patterns occur more frequently and last longer than others, and these two patterns cyclones tend to develop. This paper analyses further the tracking tendency of cyclones after their explosive development and concludes that: during the stable period of synoptic pattern, the cyclone tracks after explosive development are also stable, during the adjustment period of synoptic pattern, the cyclone tracks change with the change of long wave system over 500 hPa, while the wavelength decrease