气象2024，Vol.50Issue(3)：303-317,15.DOI:10.7519/j.issn.1000-0526.2023.111801
藏东南墨脱地区降水特征分析
Study on Precipitation Characteristics in Mêdog,Southeastern Tibetan Plateau
摘要
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.Further-more,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 reflec-tivity 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.Rain-drops 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.关键词
藏东南/降水现象仪/X波段双偏振相控阵雷达/降水特征/演变特征Key words
southeastern Tibetan Plateau/precipitation phenomenometer/X-band dual polarization phased array radar/precipitation characteristic/evolution characteristic分类
天文与地球科学引用本文复制引用
李冉,王改利,张永华,郭在华..藏东南墨脱地区降水特征分析[J].气象,2024,50(3):303-317,15.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 （2019QZKK0105）
