广东一次强飑线的地面中尺度结构特征分析

Analysis of the Characteristics of Surface Mesoscale Structure of an Intense Squall in Guangdong

利用广东省2 400余个地面自动气象站的观测资料及广州雷达站的多普勒雷达资料对2016年4月13日广东一次强飑线过程的地面中尺度特征和雷达特征进行了分析,结果表明:(1)飑线在发展旺盛时,沿着飑线方向略落后于飑线处有3个强辐合中心,强中心位于飑线凸起处;辐散区落后于飑线,大风区位于辐散中心前侧梯度最大处。大风区造成的气旋式涡度中心略落后于辐合中心。(2)飑线在地面表现为一条中尺度θ_(se)锋区。(3)飑线强盛阶段的地面中尺度场上可看到扰动高压处于辐合线顶点后侧偏右区域,扰动高压大小与阵风大小有一定正比关系。扰动低压超前于辐合中心,能作为飑线发展和大风是否出现的判断依据。(4)在飑线的弓形回波阶段的顶点处存在下击暴流,顶点后侧的弱回波通道表明伴有后侧入流急流RIJ,RIJ对弓形回波的形成、地面大风和飑线的维持和快速移动具有重要的作用。

Using the observations of more than 2 400 surface automatic weather stations in Guangdong and Doppler data from a radar station in Guangzhou, the surface mesoscale and radar characteristics are analyzed for an intense squall in Guangdong on April 13, 2016. The result is shown as follows.(1) When the squall was developing vigorously, there were three centers of strong convergence in the direction of and a little behind the squall. The centers were located where the squall had an upward-pointing curve and divergence was behind the squall. The zone of high winds was at the greatest gradient in front of the convergence centers. The center of cyclonic vorticity, caused by the zone of strong winds, was a little behind the convergence centers.(2) The squall was shown as a mesoscale θse frontal zone at the surface level.(3) In the surface mesoscale field with the intense squall, a perturbation high pressure was seen in the area at the rear and right side of the top of the convergence line. Its intensity was somewhat proportional with that of gusts. As the perturbation low pressure was in front of the convergence center, it can be used to foretell if the squall can develop and strong winds can occur.(4) A downburst existed at the top of the squall's arc-shaped echo, and a channel of weak echo at the rear of the top showed that an inflow jet stream(RIJ) was in company of the squall, which played an important role in the formation of the arc-shaped echo, surface high winds and the maintenance and rapid movement of the squall.