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江西局地短时强降水的天气学分型研究

Weather system classification of local hourly heavy rainfall in Jiangxi Province

  • 摘要: 利用1998—2019年4—9月常规高空地面观测和江西省93个国家气象观测站1 h雨量资料,对筛选出的江西204次局地短时强降水过程,研究其天气学类型、各类型的探空平均和物理量特征,并建立了短时强降水概念模型。结果表明:江西局地短时强降水可分为槽前型、槽后型、热带系统型、副高边缘型和副高控制型五种类型。其中槽前型最多,占总数的48%,常发生在高空槽前、中低层切变线附近,地面冷锋、静止锋或低压倒槽中。热带系统型发生次多,占总数的19.1%,又可分为热带气旋类和东风波类,热带系统的结构、移动路径等对短时强降水落区影响大。副高边缘型分为副高西、南、北边缘型,短时强降水常发生在副高588 dagpm线边缘、低层切变线、辐合线附近。副高控制型占总数的5.5%,强降水发生在副高控制江西全省,500 hPa江南北部或东部有中心温度低于-4 ℃的冷槽影响的背景下,强降水多产生于地面地形辐合线上、高温区内或山脉迎风坡。槽后型最少,占总数4.4%,发生在槽后西北气流下、低空急流出口区及辐合区及地面辐合线上。

     

    Abstract: Based on the conventional high-altitude and ground observation datasets and the 1-hour rainfall datasets from 93 national auto? matic weather stations in Jiangxi from April to September of 1998 to 2019, a total of 204 selected local hourly heavy rainfall events (hereinaf? ter LHR) in Jiangxi were analyzed and classified. With the analysis of synoptic meteorology, radiosonde, and physical properties, the concep? tual models of each category of these LHR events were established. The results are as follows. LHR in Jiangxi can be classified into 5 catego? ries, including Pre-Trough pattern (PRT), Post-Trough pattern (POT), Tropical System pattern (TS), Edge of Subtropical High pattern (ESH), and Control of Subtropical High (CSH) pattern. PRT is the most common type, which accounts for 48% of the total events. These events usual? ly occur in front of the high-altitude trough, near the mid-low-level shear lines, and are usually associated with cold fronts, stationary fronts, or low-pressure troughs on the surface. The second most frequent one is TS, which accounts for 19.1% of the total events. TS can also be divid? ed into the tropical cyclone type and the east wind wave type. The structure and movement of the tropical systems can significantly affect the area of LHR. ESH is divided into western ESH, southern ESH, and northern ESH. For this type, LHR events usually occur near the edge of the subtropical high 588 dagpm line, the low layer shear line, or the convergence line. CSH accounts for 5.5% of the total events. LHR happens when the subtropical high controls the entire Jiangxi Province. Particularly, when a center temperature at 500 hPa over the northern or eastern Jiangnan regions below -4℃ appears under the background of a cold trough, LHR events frequently occur on the ground convergence line, in the high-temperature area, or windward slope of mountains. POT is the least common type, which accounts for 4.4% of the events. It occurs under the northwesterly flow behind a trough, in the exit zone of the low-level jets, in the convergence zone, or on the surface convergence line.

     

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