2008年12月两次强冷空气对河南影响的差异

Influence Difference Between Two Cold Air Processes on Henan Province in December 2008

采用NCEP／NCAR资料和常规观测资料，对河南省2008年12月3—6日和19—22日的两次强冷空气过程进行对比分析，结果表明：1）两次过程前期中层均为强盛的西北气流，天气晴好，气温偏高。对河南的影响均以强降温和大风天气为主，最大降温幅度接近，3-6日过程冷空气持续时间更长，强降温范围更广；后一过程持续时间较短，降温主要在豫东北部，大风更为明显。2）前一冷空气过程为“不稳定小槽东移发展型”，后一过程为“横槽转竖型”。冷空气源地均为新地岛以东洋面；均在贝加尔湖一带形成横槽，横槽北侧的东北气流引导极地冷空气加强，形成异常强的冷高压和冷中心，是造成两次强降温的主要原因。3）第一次冷空气为偏北路径，后一过程为典型的中路路径。4）过程中大风与强的正变压、强冷空气下沉运动引起的动量下传及其到地面时的强度和落区存在紧密联系。

Based on NCEP/NCAR data and conventional observation data, two strong cold air processes happened from 3 to 6 and from 19 to 22 in December 2008 were analyzed comparatively. The results show that 1 ） before two processes, northwest current is strong, weather is fine and temperature is higher relatively. The influence on Henan mainly is high wind and strong detemperature. The cooling extent is similar, but the cold air process from 3 to 6 is larger and longer, while the latter is lasting shorter, and high wind is more obvious. 2） The process from 3 to 6 belongs to unstable small trough moving east developing pattern and the latter is transversal trough recurvature pattern. The cool air both comes from east of Novaya Zemlya. Transversal trough forms at the area of Baikal Lake, at its north northeast current strengthens cool air from polar region, and from abnormal strong cold high and cold center, which are the main reasons of strong detemperature. 3 ） The former process is north path, while the latter is typical mid-way. 4） In this process high wind is closely related to strong anallobaric, momentum downward transfer caused by the sinking motion of the strong cold air, and the falling area and strength which reach to the ground.