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.