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ISSN 1006-9895

CN 11-1768/O4

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我国东南沿岸及复杂山地后汛期降水日变化的数值研究
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厦门市气象局

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国家自然科学基金,其它


A Numerical Study of Diurnal Variation of Second Rainy-Season Rainfall in the Coastal and Complicated Topographical Regions of Southeast China
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    摘要:

    利用2009-2017年7-9月福建省逐小时地面加密自动站资料和2015-2017年7-9月厦门站的探空资料,通过K均值聚类法和中尺度数值模式(WRF3.9.1.1)理想数值模拟,分析了我国东南沿岸及复杂山地(福建)后汛期降水日变化特征,揭示了地形性热力流以及海陆风环流在热对流降水日变化形成中的作用,探讨了环境温湿廓线及风垂直廓线对热对流降水日峰值强度和日峰值出现时间的影响。结果发现:我国东南沿岸复杂山地(福建)后汛期降水日变化受地形性热力流和海陆风环流的影响和调制,白天辐射加热在复杂山地形成的地形性热力流激发出对流降雨带,午后受海风环流的影响,对流降雨带组织发展达到峰值,之后随着地形热力流和海风环流减弱雨带逐渐减弱。武夷山及周边复杂山地的降水日变化主要受地形性热力流的影响,在午后对流降水达到峰值,夜间减弱几近消失。理想数值试验进一步证实了我国东南沿岸复杂山地地形性热力流对对流降雨的触发以及海陆风环流在山地对流雨带组织发展中的作用,环境温湿廓线以及风垂直廓线对热对流降水日峰值强度以及日峰值出现的时间具有重要影响,其中环境温湿廓线的大气抬升凝结高度、大气可降水量、大气的对流不稳定度以及大气中低层湿度分布的不同,会影响热对流降水日峰值强度,并通过影响山地热力对流触发时间,改变热对流降水日峰值时间,而环境风垂直廓线的低层气流强度和方向、中低层垂直风切变的不同,会影响地形性热对流系统的启动、组织发展和移动等特征,进而影响热对流降水日峰值强度以及热对流降水日峰值时间。

    Abstract:

    In this paper, it is analyzed the diurnal rainfall variations of second rainy-season in the coastal and complicated topographical regions of Southeast China (Fujian), investigated the roles of topographical thermal circulations and land-sea breezes in the formation of diurnal variation of thermal convective rainfall and revealed the impacts of environmental temperature, moisture and vertical wind profiles upon the diurnal peak intensity and occurrence time of thermal convective rainfall with hourly surface data observed by automatic weather station of Fujian province in the periods from July to September of 2009-2017, radio-soundings at Xiamen station in the periods from July to September of 2015-2017, K-mean clustering methodology and idealized numerical simulations with mesoscale numerical model (WRF3.9.1.1). The results show as follows. The diurnal rainfall variation of second rainy-season in the coastal and complicated topographical regions of Southeast China (Fujian) are impacted and modulated by topographical thermal circulation and land-sea breeze. The topographical thermal circulation due to day-time radiation heating has an ability to initiate convective rainfall band. The convective rainfall band is organized and comes to its top under the impacts of sea breeze in the afternoon, then gradually reduces with the weakening of topographical thermal circulation and sea breeze. Idealized numerical experiments further prove the role of topographical thermal circulation in the convective rainfall initiation and that of sea breeze in the convective rainfall organization. The environmental temperature, moisture and vertical wind profiles exert an important impact on the diurnal peak intensity and occurrence time of thermal convective rainfall. The atmospheric lifting condensation level, precipitable water, convective instability and the differential distribution of moisture in the mid-lower level can impact the diurnal peak intensity of thermal convective rainfall and change its occurrence time through altering its initiation time. The differences in low-level wind intensity and direction and vertical shear of mid-lower winds of environmental wind profiles can impact the initiation, organization and movement of topographical thermal convection, and further impact its diurnal peak intensity and occurrence time.

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  • 收稿日期:2018-12-04
  • 最后修改日期:2019-06-12
  • 录用日期:2019-06-20
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