| 伊犁河谷一次极端强降水事件水汽特征分析 |
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| 引用本文： | 刘晶,周玉淑,杨莲梅,张迎新.伊犁河谷一次极端强降水事件水汽特征分析[J].大气科学,2019,43(5):959-974. |
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| 作者姓名： | 刘晶 周玉淑 杨莲梅 张迎新 |
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| 作者单位： | 中国气象局乌鲁木齐沙漠气象研究所,乌鲁木齐830002;中亚大气科学研究中心,乌鲁木齐830002;中国科学院大气物理研究所云降水物理与强风暴实验室,北京100029;中国科学院大学,北京100049;北京市气象台,北京,100089 |
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| 基金项目： | 国家自然科学基金项目41565003、41661144024,国家重点研发计划项目2018YFC1507104 |
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| 摘 要： | 2016年7月31日至8月1日,新疆伊犁河谷发生了一次极端强降水事件,多站突破降水极值。利用NCEP/NCAR 1°×1°和2.5°×2.5°再分析资料、中国地面卫星雷达三源融合逐小时降水产品、新疆地区常规观测资料、基于地基GPS观测的大气可降水量资料及基于拉格朗日方法的HYSPLIT轨迹模式结果,通过对水汽输送流函数、势函数、水汽输送轨迹和暴雨区水汽收支计算,结合伊犁河谷GPS观测分析,揭示了此次强降水期间的大尺度水汽输送、辐合特征及伊犁河谷局地水汽变化特点。结果表明:（1）强降水期间大西洋及红海均对伊犁河谷的水汽供应具有贡献,河谷处于水汽通量辐合区,向西开口的地形辐合和抬升为局地暴雨的发生提供有利的动力辐合条件。低纬度印度夏季风环流和中纬度大西洋向东输送的气流共同构成伊犁河谷极端降水天气的水汽输送通道,其中印度夏季风西南水汽输送主要集中在对流层低层,对流层中层水汽的输送以大西洋向东气流和低槽自身水汽输送为主。（2）HYSPLIT模拟结果表明暴雨区3000 m中纬度偏西路径的水汽输送最为强盛,偏南路径水汽源于阿拉伯海,对流层底层偏西、偏东路径和中层偏北路径水汽通过垂直运动补充对流层低层的水汽;5000 m水汽输送轨迹以偏西路径和低槽自身携带的水汽为主。（3）降水期间水汽集中在对流层低层,通过垂直输送项向高层输送;强降水时段暴雨区对流层低层南边界水汽流入量迅速增强,中高层水汽流入主要集中在西边界。（4）降水前槽前西南气流造成伊犁河谷测站GPS-PWV明显跃升,强降水时段受印度西南季风影响,测站PWV快速增高并维持,局地GPS-PWV的增加与大尺度水汽输送辐合增强有关。
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| 关 键 词： | 暴雨 水汽输送 拉格朗日轨迹 地基GPS |
| 收稿时间： | 2018/1/4 0:00:00 |
A Diagnostic Study of Water Vapor during An Extreme Precipitation Event in the Yili River Valley |
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| LIU Jing,ZHOU Yushu,YANG Lianmei,ZHANG Yingxin.A Diagnostic Study of Water Vapor during An Extreme Precipitation Event in the Yili River Valley[J].Chinese Journal of Atmospheric Sciences,2019,43(5):959-974. |
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| Authors: | LIU Jing ZHOU Yushu YANG Lianmei ZHANG Yingxin |
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| Institution: | 1.Institute of Desert Meteorology,China Meteorological Administration, ürümqi 830002;Center for central Asia Atmosphere Science Research, ürümqi 8300022.Laboratory of Cloud-Precipitation Physics and Severe Storms, Institute of Atmospheric Physics, Chinese Academy of Science, Beijing 100029;University of Chinese Academy of Sciences, Beijing 1000493.Beijing Meteorological Bureau, Beijing 100089 |
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| Abstract: | An extreme precipitation event occurred during 31 July to 1August, 2016, at the Yili River Valley that broke multi-station single-event precipitation records. Based on calculations of (1) the water vapor transport stream function and non-divergent (rotational) components, (2) potential function and divergent (irrotational) components, (3) the water vapor transport budget using 1°×1° NCEP/NCAR reanalysis, and (4) water vapor transport trajectories using the HYSPLIT model based on the Lagrangian method, the large-scale water vapor transport and convergence characteristics were analyzed during the heavy rainfall period. The results showed that: (1) The Atlantic Ocean and the Red Sea contributed to the water supply during the event, with the Indian summer monsoon circulation at low latitudes, and the Atlantic Ocean’s east airflow at mid-latitudes, constituting the water vapor transmission channel; convergence and orographic uplift of the terrain to the west provided a favorable dynamic convergence mechanism for the occurrence of locally heavy rain. (2) The 3000 m water vapor transmission trajectory included westward and eastward paths at the bottom layer,and the northward path at mid-troposphere, as streams of water vapor for the lower troposphere through vertical motion; the southward lower-tropospheric path provided water vapor from the Arabian Sea, while the mid-latitude water vapor transport from the west was the most powerful; The 5000 m water vapor transmission trajectory was dominated by the westward path and the low-pressure trough itself. (3) During the precipitation period, water vapor was concentrated in the lower troposphere, which was transported to the upper levels through vertical motion. The water vapor inflow from the southernmost boundary was rapidly increasing at the lower layers, while the middle and upper layer water vapor inflow derived from the western boundary. (4) Yili River Valley GPS-precipitable water vapor (PWV) values jumped due to the southwest airflow around the upper trough before the rainfall occurred, and remained high due to the influence of the Indian Southwest Monsoon during the heavy rainfall period. |
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| Keywords: | Torrential rain Transfer of water vapor Lagrange trajectory Ground-based GPS |
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