| 摘要: |
| 利用常规观测资料和NCEP再分析格点资料等,对2019年7月7～13日青藏高原东南侧滇西北地区持续性强降水天气过程进行综合诊断分析。结果表明：西太平洋副热带高压维持在中南半岛一线,伊朗高压稳定在印度西部附近,中高纬冷空气不断南下补充,使印度东部低值系统长时间存在,其前部西南气流与副高西侧偏南气流汇合后不但在滇西北形成辐合切变,还建立了水汽通道,有利于孟加拉湾水汽向滇西北输送；滇西北低层维持水汽通量散度负值,有较强的水汽辐合；整层大气呈低层辐合-高层辐散的动力配置,上升运动强烈；中低层大气高能高湿,处于对流不稳定状态,这些因素诱发和维持了此次持续性强降水天气过程。同时,滇西北西部的怒江州处于迎风坡位置上,经缅甸向东移的天气系统和暖湿气流受地形的引导和阻挡被迫抬升形成地形雨,导致怒江州降水量大于迪庆州和丽江市。 |
| 关键词: 滇西北；持续强降水；环流特征；物理量场；地形影响 |
| DOI： |
| 投稿时间：2020-09-19修订日期：2021-04-02 |
| 基金项目:青藏高原东南角“桃花汛”暴雨的天气学成因及地形影响机制研究（42075013） |
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| Analysis of a heavy rainfall process in the southeast of Qinghai Tibet Plateau and Northwest Yunnan |
| Yuanliping |
| (NJMO) |
| Abstract: |
| Based on the conventional observation data, NCEP reanalysis data and topographic data, the continuous heavy precipitation weather process in Northwest Yunnan on the southeast side of Qinghai Tibet Plateau from July 7 to 13, 2019 is comprehensively analyzed. The results show that: the Western Pacific subtropical high controls the Indo China Peninsula, the Iranian high is stable near the west of India, and the cold air in the middle and high latitudes continuously penetrates to the south, making the low value system in eastern India exist for a long time. The convergence of the southwest airflow in the front of the subtropical high and the southerly airflow in the west of the subtropical high continuously affects the northwest of Yunnan, which is conducive to the water vapor transportation from the bay of Bengal to the northwest of Yunnan. During the period of heavy rainfall, the divergence of low-level water vapor flux in Northwest Yunnan was negative, and the water vapor convergence was strong; the whole atmosphere convergence and divergence in the low-level and high-level, with strong upward movement and obvious suction effect; the middle and low-level atmosphere was in the state of convective instability due to high-energy and high humidity. Northwest Yunnan is located at the bottom of the trumpet terrain, and the high terrain on both sides is conducive to guiding the water vapor to converge in Northwest Yunnan, providing sufficient water vapor for continuous heavy rainfall; Nujiang Prefecture is located on the windward slope, and the topography forced uplift enhances the precipitation, which makes the precipitation in Nujiang Prefecture greater than that in Diqing Prefecture and Lijiang City. |
| Key words: Northwest Yunnan; heavy rainfall; circulation characteristics; diagnostic analysis; topographic influence |
