宁夏春季典型沙尘暴年环流特征量分析

利用近1960-2000年宁夏春季沙尘暴发生次数及常规气象与环流特征量、海温等资料, 首先分析得出了宁夏近41a来沙尘暴发生频次的变化规律; 其次通过对宁夏典型沙尘暴多、少年气候特征对比分析, 发现沙尘暴多、少年前期气象要素及环流特征量存在明显差异: 沙尘暴少(多)发年前一年夏季及前一年夏季到当年春季累积降水量偏多(少); 冬春季冷空气活动次数偏少(多); 前期及同期北半球极涡面积偏小(大)、强度偏弱(强); 冬季东亚大槽位置偏东(西)、强度偏弱(强); 前一年春季北太平洋海温距平场表现为厄尔尼诺遥相关分布型(反厄尔尼诺遥相关分布型)。依据作用机理, 提出了在西北地区生态环境局部治理、整体恶化背景下, 宁夏春季沙尘暴发生频次减少, 主要是东亚环流调整、冬季风减弱所致, 同时还形成了宁夏春季沙尘暴短期气候趋势预测概念模型。

Analysis on Circulation Features of Typical Spring Sandstorms in Ningxia

The data on sandstorm occurred times, conventional meteorological observation, circulation feature, sea surface temperature etc. in nearly 40 years are used to analyze the variety law of sandstorms in Ningxia as well as their relations with influencing factors. It was found out that there is obvious difference in prophase meteorological and circulation features between the years with more and less sandstorms: the shortage of precipitation of previous summer and summer to fall, less activities of cold mass in spring and winter, smaller area and weak intensity of prophase north polar vortex, easterly located and weak of east Asia trough, El Nino distributed type of north Pacific sea surface temperature anomaly previous spring all lead to less spring sandstorm, and vice versa. According to the mechanism of sandstorm it is revealed that the modification of East Asia circulation, weak winter monsoon is the main reason of less occurrence of spring sandstorm in Ningxia on in the background of regional enhanced while degrading totally. The conceptual model of climate trend of spring sandstorm in Ningxia was setup as well.