云南气象衍生地质灾害的时空分布及其影响天气系统

Spatial and Temporal Distribution of Meteorological Derived Geological Disasters in Yunnan and Its Influence on Weather System

  • 摘要: 选取云南省2011—2020年灾害普查数据,结合站点观测降水资料、NCEP再分析资料和云南气候年鉴,对云南气象衍生地质灾害的时空分布及其影响天气系统进行分析。结果表明:云南滑坡和泥石流灾害具有显著的年际变化和年内变化特征。滑坡灾害在滇西和滇西南地区为集中多发区,其次是滇东北和滇东,滇中地区为低发区。泥石流灾害主要集中在滇西北地区。汛期引发云南地质灾害的主要天气系统为切变线、两高辐合、南支槽、孟湾低压、西行台风和西南涡,其中切变线和两高辐合系统的影响最为显著。切变线附近有较明显的“鞍”型场环流,降水在切变线附近较为集中。两高辐合型可分为Ⅰ类和Ⅱ类,与切变线系统相比,两高辐合区内风场辐合强度稍弱,但系统影响范围更广、较稳定且移动速度慢,多造成持续性降雨,其较大的辐合区范围还导致强降水落区预报难度增大。

     

    Abstract: Based on the disaster census data of Yunnan Province from 2011 to 2020, combined with site observation precipitation data, NCEP reanalysis data and Yunnan Climate Yearbook, the spatial and temporal distribution of meteorological-derived geological disasters and the influencing weather systems in Yunnan Province were analyzed. The results show that the landslide and debris flow disasters in Yunnan have significant inter-annual and intra-annual variation features. In the aspect of spatial distribution, landslide disasters are concentrated in western and southwestern Yunnan, followed by northeastern and eastern Yunnan, and central Yunnan is a low-incidence area, while debris flow disasters are concentrated in northwestern Yunnan. The main weather systems causing geological disasters in Yunnan during the flood season are shear line, two-high convergence, south branch trough, Bay of Bengal low, westward typhoon and southwest vortex, among which the influence of shear line and two-high convergence system is the most significant. An obvious “saddle” shaped field circulation is found near the shear line, and the precipitation is concentrated near the shear line. The two-high convergence type can be divided into type I and type II. Compared with the shear line system, the wind field convergence intensity in the two-high convergence zone is slightly weaker, but the system has a wider range of influence, is more stable and moves slowly, resulting in continuous rainfall. The larger convergence zone also makes it more difficult to predict the heavy rainfall area.

     

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