春季次天气尺度气旋年际变化对江淮地区降水的影响
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国家重点研发计划项目(2019YFC1510201);国家自然科学基金资助项目(41575081;41741005)


Influence of interannual variation of spring subsynoptic-scale cyclones on precipitation in the Yangtze-Huaihe River valley
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    摘要:

    基于1979—2013年ERA-Interim逐日6 h的850 hPa位势高度场资料,利用气旋最外围闭合等值线自动识别方法提取了春季影响江淮地区的二维气旋集,研究了次天气尺度气旋活动年际异常与江淮地区降水异常的联系。结果表明:次天气尺度气旋活动对江淮大部分地区春季降水作用明显,贡献率达25%以上,次天气气旋活动出现对应显著的区域对流层低层气旋式涡旋和辐合运动,为局地降水增强提供了有利的动力条件。次天气尺度气旋强度的年际变化与春季江淮地区东南部降水异常及强降水频次存在显著正相关关系。当江淮地区次天气尺度气旋增强时,青藏高原至中国长江中下游地区出现异常的倒槽型环流,有利于江淮地区形成气旋式环流异常;同时,随着南方地区西南暖湿气流增强,对流层下部大气斜压性增强,促进了江淮地区次天气尺度气旋活动增强。春季青藏高原地区气柱异常加热,引起对流层低层位势高度降低,促进了南方地区西南风加强,导致江淮地区次天气尺度气旋活动增强。

    Abstract:

    Based on the daily 6 h 850 hPa geopotential height field data from ERA-Interim reanalysis data during 1979—2013,the two-dimensional cyclones affecting the Yangtze-Huaihe River valley (YHV) in spring are extracted by using the automatic identification method of outermost closed contour of cyclones.The relationship between interannual anomaly of subsynoptic-scale cyclone activity and precipitation anomaly in YHV is studied.Results show that the subsynoptic-scale cyclone activity has an obvious effect on spring precipitation in most areas of YHV,with a contribution rate of more than 25%.The subsynoptic-scale cyclone activity has corresponding significant regional cyclonic vortex and convergence motion in the lower troposphere,which provides favorable dynamic conditions for the local precipitation enhancement.The interannual variation of subsynoptic-scale cyclone intensity has a significant positive correlation with the precipitation anomaly and the occurrence frequency of heavy precipitation in the southeast of YHV in spring.When the subsynoptic-scale cyclone intensifies in YHR,an anomalous inverted trough circulation appears from the Qinghai-Tibet Plateau to the lower-middle reaches of the Yangtze River in China,which is conducive to the formation of cyclonic circulation anomaly in YHV.Simultaneously,the atmospheric baroclinicity increases in the lower troposphere when the southwest warm and moist air flow in southern China strengthens,which promotes the enhancement of subsynoptic-scale cyclone in YHV.The anomalous heating of air column over the Qinghai-Tibet Plateau in spring,which leads to the decrease of potential height in the lower troposphere and the strengthening of southwest flow in southern China,may be the main reason for the enhancement of subsynoptic-scale cyclone activity in YHV.

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卢楚翰,王思涛,叶佳馨,杨敏,李芹芹,何文悦,周洁雯.2021.春季次天气尺度气旋年际变化对江淮地区降水的影响【J】大气科学学报.44.2:252.260

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  • 收稿日期:2020-04-07
  • 最后修改日期:2020-07-25
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  • 在线发布日期: 2021-04-25
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