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气象:2024,50(3):303-317
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藏东南墨脱地区降水特征分析
李冉,王改利,张永华,郭在华
(南京信息工程大学大气物理学院,南京 210044; 中国气象科学研究院灾害天气国家重点实验室,北京 100081; 墨脱国家气候观象台, 墨脱 860700;广东省气象服务中心,广州 510080;成都信息工程大学,成都 610225)
Study on Precipitation Characteristics in Mêdog, Southeastern Tibetan Plateau
LI Ran,WANG Gaili,ZHANG Yonghua,GUO Zaihua
(School of Atmospheric Physics, Nanjing University of Information Science and Technology, Nanjing 210044; State Key Laboratory of Severe Weather, Chinese Academy of Meteorological Science, Beijing 100081; Mêdog National Climate Observatory, Mêdog 860700;Guangdong Provincial Meteorological Service Center, Guangzhou 510080;Chengdu University of Information Technology, Chengdu 610225)
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投稿时间:2023-02-19    修订日期:2023-10-17
中文摘要: 墨脱位于藏东南雅鲁藏布大峡谷水汽通道入口处,是青藏高原年降水量最多的地区。本研究使用墨脱云降水综合观测试验以来三年(2019—2021年)的自动雨量计数据,分析了墨脱降水的月变化和日变化特征。然后基于同址的降水天气现象仪和X波段双偏振相控阵雷达观测数据,探究墨脱两次强降水过程的发展演变特征。结果表明:从统计结果来看,墨脱降水天数超过全年的70%,以降水率<5mm·h-1的弱降雨为主,日降水量<10mm的小雨的发生率最高,但10mm≤日降水量<25mm的中雨产生的降水量最大。墨脱降水存在明显的月变化和日变化特征,受印度洋季风影响,降水主要发生在6—9月。受山谷风影响,降水主要发生在夜间。对于降水过程而言,由高原涡和南支槽影响下的系统性暴雨,范围大、持续时间长,降水主要由直径小于2 mm的雨滴产生,雷达反射率因子普遍不超过35dBz。而由地形强迫引起的局地短时强对流降水过程,雨滴谱分布更宽,雨滴浓度更高,直径大于2 mm的雨滴对降水量的贡献最大,雷达反射率因子超过45dBz,风暴的后向传播形成“列车效应”。
Abstract:Mêdog located at the entrance of the water vapor channel of the Yarlung Zangbo Grand Canyon, has the largest rainfall totals over the Tibetan Plateau. In this article, the monthly and diurnal variation characteristics of precipitation in Mêdog are analyzed with the automatic rain gauge data collected from 2019 to 2021. Based on the observations from precipitation phenomenometer and X-band dual polarization phased array radar, the evolution characteristics of two heavy precipitation events that occurred in Mêdog are explored. The results show that precipitation frequently occurs in Mêdog with rainy days exceeding 70% of the whole year and light rain less than 5 mm·h-1 as dominant rainfall type. The occurrence frequency of light rain with daily rainfall less than 10 mm is the highest, while moderate rain with daily rainfall between 10 mm and 25 mm is the largest contributor to rainfall amount. The Mêdog precipitation features obvious monthly and daily variations. The highest occurrence frequency of rainfall is in the monsoon season from June to September, which is attributed to the warm and humid airflow from the Indian Ocean. Furthermore, rainfall frequently occurs at night due to the mountain-valley wind, which is related to the valley terrain of Mêdog. In terms of the evolution of heavy rainfall events, the systematic heavy rainfall events under the effect of Tibetan Plateau vortex and South Branch Trough are characterized by expansive area and long duration. The rainfall event is dominated by small raindrop less than 2 mm, and the radar reflectivity factor is generally smaller than 35 dBz. However, local short-duration convective precipitation event forced by topographic has a wider raindrop size distribution width and higher raindrop concentration. Raindrops larger than 2 mm in diameter contribute maximum rainfall amount with radar reflectivity factor of convective core exceeding 45 dBz. The backward propagation of the storm generates a “train effect” during the heavy rainfall event of this heavy rainfall event.
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基金项目:第二次青藏高原综合科学考察研究项目(2019QZKK0105)、中国气象科学研究院科技发展基金项目(2023KJ041)、中国气象科学研究院基本科研业务费重点项目(2023Z009)和广东省气象局科学技术研究项目(GRMC2022Z05、GRMC2021XQ03)共同资助
引用文本:
李冉,王改利,张永华,郭在华,2024.藏东南墨脱地区降水特征分析[J].气象,50(3):303-317.
LI Ran,WANG Gaili,ZHANG Yonghua,GUO Zaihua,2024.Study on Precipitation Characteristics in Mêdog, Southeastern Tibetan Plateau[J].Meteor Mon,50(3):303-317.