广州短时大暴雨多普勒特征和成因分析

利用广州CINRAD-SA新一代天气雷达各种产品,对发生在广州市的一次短时大暴雨的多普勒特征进行了详细分析,同时分析了该过程的天气特征及其变化,探讨了短时大暴雨的成因。结果表明:此次短时大暴雨产生于低空急流、低层辐合、高层辐散的强抽吸作用的有利环流背景下,由多个单体排列成与单体移动方向一致的走向,依次穿越同一地区造成的。强度最强、强回波维持时间最长的单体同时伴有弱中气旋特征,并与强降水发生区域相对应。逆风区对对流的维持和加强起到了十分重要的作用。     

新一代多普勒天气雷达广东省区域拼图初探

介绍了利用广东省四部新一代多普勒天气雷达(CINRAD/SA)的产品数据进行区域拼图的基本方法和功能,给出了该拼图系统的各项技术参数,同时介绍了其在区域灾害性天气监测和预警中的应用。     

COMPARISONS BETWEEN DOPPLER AND SIMULATED FEATURES OF A SUPERCELL

Firstly, typical features of a supercell, which occurred in Guangzhou on August 11, 2004, are discussed by using the new generation weather radar data. V-notch, finger-echo, weak echo region, overhang and echo-wall are observed from reflectivity products. A vertical cross section of the radial velocity is made along the direction of the low-level inflow and across the maximum reflectivity core, which displays a part of strong updraft and downdraft. Secondly, a 3-D convective storm model is used to simulate the supercell. The maximum reflectivity and the core thickness of the simulated radar echo are 75 dBz and 14km, respectively. These values are more than the counterparts that are detected by radar. The reason is that attenuation is not calculated in the model. The wind field structure is also given when the storm is the strongest. Divergence, caused by thunderstorm outflow, is in the low level. In the middle and high level, convergence is dominant, but the plume is not simulated at the top. Finally, the evolution of the simulated vertical motion is documented. The interaction between the environmental wind and the updraft, which is formed by the convergence on the ground at the beginning, makes the storm stronger. Then, downdraft occurs and grows. When it becomes dominant, the supercell collapses.     

台风远外围大范围强对流天气成因综合分析

为加深对台风外围发生的强对流天气的认识，提高对华南地区强对流天气潜势预报和预警的能力，利用广东中尺度天气监测网的多普勒雷达、自动站资料和NCAR／NCEP的再分析资料等对2004年8月发生在台风云娜外围一次强对流天气的天气形势背景、水汽、CAPE、SI、WI、垂直速度和海风辐合等进行了综合分析。结果表明：华南前期受副热带高压和云娜外围下沉气流作用，地面连续高温，使低层大气内能不断积蓄；台风云娜向西北移动的过程中，华南上空的副热带高压和下沉气流减弱，在其外围弱低压槽、海风辐合和干线共同作用下触发了强对流；台风外围的稳定度具有明显的波动性，强对流在台风外围螺旋云带末端的高温、不稳定和相对高湿舌发生；风指数WI用于华南地区雷雨大风预报比其它指数更有效。     

最不稳定层的确定及应用

以清远探空站资料为基础，对2003~2004年清远及其附近地区强对流（雷雨大风、冰雹、龙卷风，下同）日最不稳定层位置及状态进行了统计，并把最不稳定层同几个规定层进行比较，总结出三种主要的产生强对流天气的T—LnP图型，为强对流天气的预报提供了极为有利的参考。     

"18·8"广东季风低压持续性特大暴雨成因分析

利用NCEP FNL 1°×1°再分析、地面观测和广东雷达等资料,对2018年8月27日—9月1日广东季风低压持续性特大暴雨过程进行了综合分析,主要结论如下:(1)在南亚高压稳定少动、西太平洋副热带高压呈异常双脊形态、强盛的西南季风低空急流北抬的大尺度环流背景下,季风低压显著发生发展并缓慢偏西移,促使本次广东持续性特大暴雨过程的发生。(2)季风低压的生命史可划分为两个阶段:波动加强阶段与减弱消亡阶段。季风低压强度演变与暴雨落区范围大小的逐日分布是同步,但与日最大降水量逐日演变不完全同步。在低压由强转弱并加速远离阶段(8月30日),处于季风低压外围倒槽区的粤东地区却发生了破纪录的极端暴雨。(3)粤东极端暴雨发生在边界层动力辐合及水汽辐合最强、对流层中低层的层结最不稳定阶段,中层南海高压与季风低压的相互作用为暴雨增幅提供了有利条件。来自海洋的偏南暖湿气流北推与前期MCS冷池出流相互作用导致粤东沿海地面辐合线的形成,辐合线西段受莲花山脉地形阻挡和抬升作用长时间停滞维持,致使极端强降水回波的触发和维持。(4)雷达回波演变可划分为三个阶段:块状弱回波西移阶段、带状回波叠加强短雨带东北移阶段和回波减弱东南移阶段。强降水回波呈典型的低质心暖云对流降水结构。     

双线偏振多普勒雷达及其探测技术的应用

介绍了双线偏振多普勒天气雷达的基本原理和双偏振参量。阐述了几种较常使用的估测降水强度的算法,并分析了不同算法之间的差异。讨论了利用双线偏振雷达观测资料识别冰雹区的方法,其中,基于模糊逻辑技术的冰雹识别模式,不仅可以反映出实际的冰雹区位置,而且还可以对其分类。     

多普勒雷达VWP产品在一次大暴雨过程中的特征

对广州“2005.6.5“大暴雨过程中广州多普勒雷达的VWP产品特征进行了分析,结果表明:大暴雨出现前VWP产品“ND“区逐渐萎缩,高空风发生显著变化的层次与“ND“转为非“ND“的区域相对应;大暴雨结束前出现稳定的“ND“;VWP可以得到高空风的分布,推断垂直风切变,低层入流的强度、厚度及风暴核的高度和三维结构;VWP可推断风暴的平流速度,当平流速度较大时,风暴的移向、移速一般较稳定,当平流速度偏小时,风暴易发生移速和移向的突变,甚至少动,造成局地强降水.     

Evolution of moist potential vorticity during a warm-zone heavy rainfall event in the Pearl River Delta

First,based on routine meteorological data,the synoptic characteristics of a heavy warm-sector rainfall that occurred on June 13,2008 in the Pearl River Delta were analyzed.Second,a mesoscale numerical model,Weather Research and Forecasting(WRFV2.2),was used to simulate the heavy rainfall. Diagnostic analyses were done of moist potential vorticity(MPV)for its horizontal components(MPV2) and vertical components(MPV1)based on the simulation results of WRFV2.2 to identify the mechanism of the rainfall development.The results showed that the heavy rainfall occurred when there were high MPV1 in the upper levels and low MPV1 and high MPV2 in the lower levels.Disturbances of high MPV1 in the upper levels came from the southwest or northwest,those of low MPV1 in the lower levels came from the southwest,and those of high MPV2 came from the south.Disturbances of low MPV1 at low levels were the direct cause of convective instability.Enhanced vertical shear of meridional wind led to increased MPV2 at lower levels,strengthened baroclinicity,and active warm and wet flows.These distributions of MPV helped to trigger the release of unstable energy and produce warm-sector heavy rainfall.As it integrates the evolution of dynamic and thermal fields,MPV is able to reveal the development of this heavy rainfall effectively.     

“2010.5.22～23”广东强对流过程综合分析

利用常规探空和地面观测资料、NCEP再分析资料、雷达回波等资料,分析了 2010年5月22～ 23日广东强对流暴雨过程的特征,并探讨了此次强对流暴雨产生的成因及落区.结果表明:此次天气过程是在高空槽、中层切变、地面冷空气及地面辐合线共同配合下产生的;分析还表明,在强对流发生前,k指数等5类探空指数对强对流发生发展有较好...