2007年3月中国东部北方地区一次强灾害性暴风雪事件的成因初探

A preliminary investigation on causes of the catastrophic snowstorm in March,2007 in the northeastern parts of China

中文关键词:  暴风雪，灾害性天气，遥相关，天气预报

英文关键词:Snowstorm, Catastrophic weather, Teleconnection, Weather forecast

中文摘要:

      2007年3月3—5日，中国东部北方地区发生了近50年来历史同期最强的一次暴风雪事件，给该地造成了严重的灾害和损失。通过分析这次暴风雪事件发生前期和同期的大尺度大气环流异常，探讨形成这次极端天气的可能物理机制。研究结果表明，在这次暴风雪事件发生的前两周中，存在持续异常的北极涛动、南极涛动、欧亚型遥相关以及北太平洋涛动等大气模态。这些异常环流在中国东部沿岸地区引起了强劲的偏南风，由此给中国东部北方地区源源不断地输送暖湿空气，使得该地的水汽含量和气温不断升高，为这次暴风雪事件的发生准备了良好的暖空气条件。当3月初大气环流发生调整，极地冷空气南下时，强劲的冷、暖空气交汇于中国东部北方地区，从而在该地形成了强大的冷锋系统，最终导致了这次强暴风雪事件的发生。研究结果表明，在预报与降水相关的天气时，必须考虑事发前期异常大气环流的信息，关注预报区域前期水汽的积累状况，这对于提高降水预报、特别是强降水预报的水平有着重要的意义。

英文摘要:

      A snowstorm deposited record breaking snowfall over the northeastern parts of China on March 3-5, 2007, resulting in severe disasters and heavy losses. The objective of this study is to explore the possible mechanism responsible for this extreme event by analyzing the atmospheric circulation anomalies prior to and during the event. The results show that there had been persistent strong anomalous Arctic Oscillations, Antarctic Oscillations, Eurasian teleconnection pattern, and North Pacific Oscillations in about two weeks before the event. Those anomalous atmospheric circulations stimulated the strong anomalous southerlies along the east coastal regions of China, which persistently transferred the warm and wet air to the northeastern areas of China, thus raising the moisture content and air temperature there and providing proper warm and wet conditions for the occurrence of the extreme snowstorm event. When the atmospheric general circulation changed in early March, the strong cold air from the high latitudes met the warm air over the northeastern China, resulting in a remarkably cold front and associated strong snowfall and low temperature in that region.The results of this study imply that the anomalous atmospheric circulation and the cumulative moisture condition in the forecast region in the early stage should be fully considered, which is helpful to the improvement of rainfall forecast, especially the heavy rainfall forecast.