潘佳文,彭婕,魏鸣,郑秀云,吴伟杰,高珊,吴举秀,蔡菁. 2022. 副高背景下极端短时强降水的双偏振相控阵雷达观测分析[J]. 气象学报, (0):-, doi:[doi]
副高背景下极端短时强降水的双偏振相控阵雷达观测分析
Analysis of an extreme flash rain event under the background of Subtropical High based on dual-polarization phased array radar observations
投稿时间:2021-12-30  修订日期:2022-06-07
DOI:
中文关键词:  双偏振相控阵雷达,极端短时强降水,弱天气尺度背景,地形降水
英文关键词:Dual-polarization phased array radar, Extreme flash rain, Weak synoptic-scale background, Orographic precipitation
基金项目:
作者单位邮编
潘佳文 厦门市海峡气象开放重点实验室厦门市气象局 361012
彭婕  361012
魏鸣 气象灾害预报预警与评估协同创新中心,南京信息工程大学 210044
郑秀云  361012
吴伟杰  361012
高珊  350001
吴举秀  250031
蔡菁  350001
摘要点击次数: 28
全文下载次数: 119
中文摘要:
      为了研究副热带高压背景下极端短时强降水系统的动力和云物理结构特征。利用厦门X波段双偏振相控阵雷达观测数据,采用多普勒雷达风场反演技术,并结合高精度地形数据,对2021年8月11日发生在厦门地区的一次极端短时强降水事件进行了分析。研究表明:(1)本次过程发生在副高控制之下,具有弱天气尺度强迫特征。地面辐合线促进了线状对流系统的形成,其后向传播过程导致了局地极端强降水的发生。(2)对流系统的中层存在大粒子累积区,大粒子的下泻导致雨强增大。倾斜上升(下沉)气流的配置使得大粒子的下泻不会压灭上升气流,有利于对流系统的发展与维持。下沉气流与偏南气流相遇,触发了下游对流系统的发展,形成后向传播。(3)在弱天气尺度背景下,局地地形对于降水系统的影响作用得以被凸显。地形所导致的低层辐合使得差分反射率因子、差分相位常数等双偏振参数在迎风坡处明显增大,且大值区在此处维持。更大、更浓密的降水粒子形成了极高的降雨效率。(4)暖雨过程和冰相过程在本次极端降水事件中并存,前者对雨水的形成起主要作用,冰相粒子的融化加速了这一进程。强降水时雨滴的破碎和碰并趋于平衡,雨强的增大取决于雨滴浓度的增加。因此,差分相位常数可作为判断雨强是否增大的指标。(5)差分反射率因子柱与差分相位常数柱的演变对于地面雨强的变化具有预示性,特别是在持续降水过程中,差分反射率因子(差分相位常数)柱的再度发展预示着降水系统的再次增强。
英文摘要:
      An extreme flash rain event under the background of Subtropical High that occurred in Xiamen on August 11 2021 is analyzed based on X-band dual-polarization phased array radar observations. The dynamic and microphysical characteristics of the precipitation system are analyzed using the Doppler radar wind field retrieval technique, combined with high-precision topographic data. The study yields the following results. (1) The event took place under the control of the Subtropical High, with the characteristics of weak weather-scale forcing. The surface wind convergence line promoted the formation of a quasi-linear convective system (QLCS), and the back-building process of the QLCS led to local extreme precipitation event. (2) The updraft lifted the raindrops to the mid-level, forming a large particle accumulation area. When it descended, the rain intensified. The configuration of inclined updraft and downdraft ensured that the falling of large particles would not suppress updraft, which was beneficial to the development and maintenance of convective system. The downdraft triggered the development of the downstream convective system, forming a back-building process. (3) The impact of local terrain on the precipitation system was highlighted under the weak synoptic scale background. The low-level convergence caused by the local terrain causes the polarization parameters such as differential reflectivity (Zdr) and specific differential phase (Kdp) to increase significantly on the windward slope, and the large value area is maintained here. The larger, denser precipitation particles produced extremely high precipitation efficiency. (4) The warm rain process and the ice phase process coexisted in this extreme precipitation event. The warm rain process played a major role in the formation of rain, and the melting of ice particles accelerated this process. At high rain rate, the breakage and collision of raindrops tend to balance, and the increase of rain rate depends on the increase of raindrop concentration. Therefore, Kdp can be used to determine whether the rain rate is increasing. (5) The evolution of the Zdr and Kdp column is an appropriate index that can reflect the development of the surface rain rate. During a continuous precipitation process, the re-development of the Zdr (Kdp) column height occurs earlier than that of the precipitation system.
查看全文   查看/发表评论  下载PDF阅读器
分享按钮