2008年1月河南低温雨雪天气的中期环流特征

Medium-term Circulation Characteristics of Low Temperature and Snow Rainfall Weather in January 2008 in Henan

利用NCEP/NCAR逐日再分析资料,对2008年1月中下旬河南省出现的低温雨雪天气的特征、大尺度环流形势以及高低层大气的状态进行分析。结果表明:2008年1月西太平洋副热带高压异常偏强偏北,有利于西南暖湿气流沿副高边缘向北输送,影响河南;东亚地区500 hPa高度距平东西部差距显著,标志着亚洲中纬度地区槽脊加强,环流经向度加大;东亚有较强冷空气活动,东亚从3-6候850 hPa明显的经向风负距平,也反映该时段冷空气活动较强。分析结果还显示,河南省冬季的持续低温雨雪天气与乌拉尔山阻塞高压的建立和维持有紧密联系:从乌拉尔山阻高的建立、维持到河南省低温雨雪天气的开始,从乌拉尔山阻高的崩溃到河南省雨雪天气的结束,中间的时间间隔约为5-10天。因此,乌拉尔山阻高的建立、维持和崩溃,对河南省低温雨雪天气的开始和结束有一定的指示意义。

Based on the NCEP/NCAR daily reanalysis data, the characteristics, the large-scale circulation and the atmospheric status on high and low level of the low temperature and snow rainfall during mid and last ten days in January 2008 in Henan are analyzed. Results show that the subtropical high is stronger and moves northward, which is beneficial to SW flow to transport northwards along its edge and to influence Henan. The 500 hPa height anomaly is obviously different in east and west, which implies the enhancement of the trough and ridge in the middle latitudes in Asia and the increase of the circulation meridionality. There is stronger cold air in East Asia, which is showed by the obvious negative meridional wind anomaly on 850 hPa during 3 to 6 pentad. Results also show that from the establish and maintain of the Ural blocking high to the beginning of the low temperature and snow rainfall, and from the collapse of former to the ending of latter, there is also 5 to 10 days, which means that the establish, maintain and collapse of the Ural blocking high has indicative significance to the beginning and ending of the low temperature and snow rainfall.