基于雷达观测的福建暖季对流天气特征分析

doi:10.11755/j.issn.1006-7639-2024-06-0865

摘要/Abstract

摘要：

研究福建暖季对流系统分布特征对对流天气的预报预警有重要参考意义。利用福建建阳、龙岩、长乐、厦门4部天气雷达2008—2017年资料识别暖季（4—8月）对流，分区域分析对流的空间、时间和垂直结构，以及不同面积和伸展高度的对流系统的空间和日变化特征。结果表明：福建暖季的5—6和8月为对流活动高峰期；暖季对流具有明显的区域分布特征，4—6月对流高发区位于内陆，7—8月位于沿海山脉一带；6—8月以中深对流为主，4月以大面积对流为主，5—6月以中等和大面积对流为主，7—8月以中等和小面积对流为主。对流的垂直结构月分布有差异，中等强度对流的回波强度7—8月最强，西北部回波发展高度最高。对流频数存在明显的日变化，对流常发生于15：00—16：00（北京时），7—8月以午后单峰为主，4—5月呈双峰或多峰特征。面积越大的对流系统频数峰值出现越迟，中深和深对流午后峰值明显。5—6月内陆夜间到清晨对流高发由边界层惯性振荡形成风场的日变化及其扰动风与地形相互作用造成，8月沿海山脉对流高发原因是午后沿海山脉处于近地层加热中心、风场辐合和能量大值区中。

关键词: 天气雷达, 福建, 暖季, 对流, 时空特征

Abstract:

Studying the distribution of convection during the warm season over Fujian Province has important significance for forecasting and warning of convective weather. Based on four weather radars data of Jianyan, Longyan, Changle and Xiamen in Fujian from 2008 to 2017, convection in warm season (from April to August) was identified, and the spatial-temporal and vertical structure of convection, as well as spatial and diurnal variation characteristics of convective systems with different areas and extension heights were analyzed. The results show that the peak period of convective activity is from May to June and August during the warm season in Fujian. The convection in warm season has obvious regional distribution characteristics, the high incidence area is located in the inland from April to June, and from July to August it is in the coastal mountains. From June to August, it is dominated by medium-deep convection, and it is dominated by large area convection in April, and from May to June and from July to August it is dominated by medium and large area convection, medium and small area convection, respectively. The monthly distribution of vertical structure of convection is different. The echo intensity of moderate convection is the maximum from July to August. The echo extension height in northwest Fujian is the highest. There is obvious diurnal variation of convective frequency. Convection often occurs from 15:00 to16:00 (BST), and it is the mainly single peak in the afternoon from July to August, while from April to May there are bimodal or multi-peak. The frequency peaks of convective systems with larger area appear later, and the mid-deep and deep convective peaks are obvious in the afternoon. From May to June, the high incidence of inland convection from night to morning was caused by the diurnal variation of the wind field formed by the inertia oscillation of the boundary layer and the interaction between the disturbing wind and terrain. In August, the high incidence of convection in coastal mountains was caused by the fact that the coastal mountains are located in the near ground heating center, the convergence of wind field and the high energy value area in the afternoon.

Key words: weather radar, Fujian, warm season, convection, spatial-temporal features

中图分类号:

P458.1+21.1

冯晋勤, 赖巧珍, 蔡菁. 基于雷达观测的福建暖季对流天气特征分析[J]. 干旱气象, 2024, 42(6): 865-877.

FENG Jinqin, LAI Qiaozhen, CAI Jing. Analysis on weather characteristics of convection during the warm season over Fujian Province based on radar observations[J]. Journal of Arid Meteorology, 2024, 42(6): 865-877.

图/表 9

图1 福建地形分布及4部天气雷达覆盖范围（阴影为地形高度）

Fig.1 Topography of Fujian Province and distribution of four weather radar stations （The shaded is for terrain height）

图2 2008—2017年4—8月建阳、龙岩、长乐和厦门4部天气雷达观测的逐月累计对流频数空间分布（单位：次）

Fig.2 The spatial distributions of monthly cumulative convective frequencies （Unit： times） from April to August during 2008-2017 observed by four weather radars in Jianyan， Longyan， Changle and Xiamen

图3 2008—2017年4—8月4部雷达观测的对流频率日变化（a）建阳，（b）龙岩，（c）长乐，（d）厦门

Fig.3 Diurnal variation of convective occurrence frequencies observed by four radars from April to August during 2008-2017 （a） Jianyan，（b） Longyan，（c） Changle，（d） Xiamen

图4 2008—2017年4—8月4部雷达观测的对流反射率因子第50、第90百分位数的垂直廓线与0 ℃、-20 ℃层平均高度（a）建阳，（b）龙岩，（c）长乐，（d）厦门

Fig.4 Vertical profiles of the 50th，90 th percentiles of the convective reflectivity factor and the average height of the 0 ℃ and -20 ℃ layers observed by four radars from April to August during 2008-2017 （a） Jianyan，（b） Longyan，（c） Changle，（d） Xiamen

图5 2008—2017年4—8月建阳、龙岩、长乐和厦门4部天气雷达探测的不同面积对流系统出现频数分布（单位：次）

Fig.5 Occurrence frequency distributions of different area convective system from April to August during 2008-2017 detected by four weather radars in Jianyang， Longyan，Changle and Xiamen （Unit： times）

图6 2008—2017年4—8月不同面积、不同回波高度的对流系统发生频率日变化

Fig.6 Diurnal variation of occurrence frequencies of convective system with different area and echo height from April to August during 2008-2017

图7 2008—2017年4—8月500 hPa位势高度（填色，单位：gpm）与风场（风矢，单位：m·s-1）（左），850 hPa比湿（填色，单位：g·kg-1）和风场（风矢，单位：m·s-1）（中），地面风场（风矢，单位：m·s-1）和对流有效位能（填色，单位：J·kg-1）（右）的月平均分布

Fig.7 The monthly mean distribution of potential height （the color shaded， Unit： gpm） and wind （wind vectors， Unit： m·s-1） fields （the left） at 500 hPa， the specific humidity （the color shaded， Unit： g·kg-1） and wind （wind vectors， Unit： m·s-1） fields at 850 hPa （the middle）， the surface wind （wind vectors， Unit： m·s-1） fields and the convective available potential energy （the color shaded， Unit： J·kg-1）（the right） from April to August during 2008-2017

图8 建阳6月（a、b）与龙岩5月（c、d）对流频数分布（a、c）及对流高发区对流频数日变化（b、d）（单位：次）

Fig.8 The convective frequencies distribution （a， c） and diurnal variation of convective frequencies in high occurring area （b， d） in June in Jianyang （a， b） and May in Longyan （c， d）（Unit： times）

图9 2008—2017年5、6月02：00（a、b）、05：00（c、d） 900 hPa扰动风场（单位：m·s-1）和8月11：00（e、g）、14：00（f、h）地面气温偏差（e、f，单位：℃）及925 hPa风场（g、h，单位： m·s-1）（阴影为地形高度）

Fig.9 The disturbance wind field （Unit： m·s-1） of 900 hPa at 02：00 （a， b）， 05：00 （c， d） in May and June， the surface temperature deviation （e， f， Unit： ℃） and the 925 hPa wind field （g， h， Unit： m·s-1） at 11：00 （e， g） and 14：00 （f， h） in August during 2008-2017 （The shaded area represents the height of the terrain）

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