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Due to the topography and local nonuniform distribution of heating, extratropical cyclones in the lower troposphere usually have complex shapes and structures, and there remain some uncertainties in identifying them. Using a modified cyclone area automatic objective recognition algorithm for cyclones, we investigated the patterns of spring cyclone activities affecting Changjiang River-Huaihe River valleys (CHV) of China during the previous 37 years. The results indicated that the algorithm performs well in reproducing the cyclogenesis, movement, and cyclolysis of cyclones in CHV. Three new perspectives were noted. (1) Most influential cyclones have relatively short travel distances and lifetimes, they are typically excluded when conducting synoptic-scale cyclone tracking. (2) The cyclogenesis location of influential cyclones in spring displays multi-source characteristics. In particular, the influential cyclones originated in northern China account for 43% with more marked mobility compared to the locally generated cyclones, although most of their centers do not enter CHV. (3) Multi-center cyclones appear mainly in Da Hinggan Mountains which is on the east side of the Mongolian Plateau and over the East China Sea. These cyclones are relatively large in horizontal scale and have relatively long lifetimes. 相似文献
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春季影响江淮地区的天气尺度气旋活动与同期降水的联系 总被引：2，自引：1，他引：1
本文基于1979~2013年ERA-Interim逐日4次的850 hPa位势高度场资料,利用基于最外围闭合等值线的气旋区客观识别方法得到春季影响江淮地区的二维气旋集,依据水平尺度划分了天气尺度气旋并分析该区域气旋强度的时空分布特征以及气旋活动与站点降水异常的关系,结果表明:天气尺度气旋活动与江淮地区降水异常、强降水事件发生频次均存在显著的正相关关系。气旋活动指数高-低年份差值分析发现,随着气旋活动指数增强,东北亚地区对流层中上层增温并伴随异常高压中心出现,促使其南部南北经向温度梯度以及高空西风急流偏弱。这有利于江淮区域北部异常正涡度平流输入,同时江淮地区对流层低层形成横槽型环流,江淮区域南部及其上游地区对流层中下层出现异常西南气流,有利于江淮区域涡度增大,相应的低空辐合、高空辐散垂直结构,为天气尺度气旋发展与维持提供了有利的动力抬升条件。横槽型异常环流配置有利于江淮区域南部的西南暖湿气流和北部的异常西向/西北向水汽输入和堆积,导致区域云量以及降水异常的增多。 相似文献
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