Based on thunderstorm gales data in recent 40 years and the conventional and new monitoring data in recent 18 years in Shanxi Province, the spatial and temporal distribution of thunderstorm gales in Shanxi Province are analyzed firstly, and then the weather types, characteristic physical quantity thresholds and conceptual models of thunderstorm gales are studied by using the methods of cluster analysis and mesoscale weather analysis. The results show that the average number of thunderstorm gale days in Shanxi had the regional distribution characteristics with more in the north and less in the south, more in mountainous areas and less in plain, and more in western mountainous areas and less in eastern mountainous areas. The extreme thunderstorm gales mainly occurred in the north of Shanxi and Lüliang mountainous regions. The annual thunderstorm gales days in the western mountainous area showed an increasing trend, while there were no changes or decreasing trends in other areas. The thunderstorm gales mainly occurred from May to August, accounting for 75% of the total days of thunderstorm gales in the whole year, and thunderstorm gales occurred most frequently at 16:00 and 21:00 (Beijing Time) in a day. The flow patterns of thunderstorm gales in Shanxi are mainly divided into six types, which are forward-tilting trough, backward-tilting trough, transverse trough, subtropical high and low-level warm shear line, subtropical high and low-level cold shear line, and northwest air flow. The K index threshold of all patterns from April to May was significantly lower than that from June to September, while the temperature difference between 850 hPa and 500 hPa was obviously higher than that from June to September. When each pattern meets the characteristic physical quantity thresholds of each month, it can trigger the strong thunderstorm gale weather in Shanxi, while the flow pattern configuration of forward-tilting trough has the highest percentage of triggering extreme thunderstorm gales. Over the same period, the K indices of the patterns of backward-tilting trough, subtropical high and low-level warm shear line, subtropical high and low-level cold shear line are significantly higher than those of the patterns of forward-tilting trough and northwest air flow, while the Si index of the forward-tilting trough is obviously higher than that of other patterns, which indicated that the dynamic instability condition of the forward-tilting trough triggering thunderstorm gale is better than the thermal instability condition. The CAPE and 0 ℃ layer height thresholds of the patterns of subtropical high and low-level warm and cold shear lines are significantly higher and the thresholds of T-T_d and cloud top black body temperature in the lower layer are significantly lower than those of the other four patterns. Whether hail is accompanied by thunderstorm gale process can be accurately judged by 0 ℃ layer height threshold of each month.

A forest fire occurred in Qinyuan County, Shanxi Province on June 5, 2020. Based on the analysis of weather situation, radar echo, lightning location and other multi-source meteorological data, and European Centre for Medium-Range Weather Forecasts （ECMWF） fifth-generation global atmospheric reanalysis （ERA5）,the evolution characteristics of meteorological elements including temperature and precipitation were analyzed in the early stage and during the forest fire, and combined with the field investigation, the cause of the forest fire were given. The results show that the forest fire was caused by a positive lightning, the lightning point was at the edge of convective cloud and the lightning occurred at 15：39 BST on June 5, with the current intensity of 42.2 kA.There was no precipitation in the areas around fire site for 2 consecutive days in the early stage, the 2 m temperature in the areas around fire site increased significantly on the day of the forest fire, with the air temperature of 30-33 ℃, and the precipitation was less than 0.1 mm and it was breezy.

 Based on cloud to ground (CG) lightning data from ADTD and VLF-3D lightning positioning system and lightning disaster records in Shanxi Province in 2017, the temporal and spatial distribution and current intensity of CG lightning detected by  two systems were comparatively analyzed. The results show that the detection efficiency of three-dimensional system to CG lightning was higher than that of ADTD system, and the number of detected lightning by three-dimensional system was twice as large as that of ADTD system. The positioning accuracy of three-dimensional system to lightning disasters was higher than that of ADTD system. The daily (except for the positive lightning) and monthly variation characteristics of monitored CG lightning by three-dimensional system and occurrence time of peak values were basically consistent with ADTD system. Compared with ADTD system, the high-value region of lightning density with 3.0 fl·km-2·a-1 and above from three-dimensional positioning system increased significantly, while the minimum values below 0.3 fl·km-2·a-1 reduced greatly.

Plant litter is an important part of ecosystem in Mu Us sandy land, and its stock volume and redistribution process play important roles in affecting nutrient cycling between surface soil and plant and soil erosion resistance. Based on the field survey and sampling data, the spatial distribution characteristics of litter of Salix psammophyla normal plant were studied in typical sand dunes of southeastern edge of Mu Us sandy land. The results show that the distribution patterns of Salix litter approximately appeared concentric circle, fan-shape and crescent-shape with the centre of Salix base under the long-term influence of the northwest wind, and the biomass of litter decreased significantly with the increase of the distance (30 cm, 60 cm and 90 cm) from the Salix base. Compared with the concentric circle pattern, the biomass of litter for crescent-shaped and fan-shaped patterns decreased in the northwest of base and increased in the southeast of base, especially for the crescent-shaped pattern the changes were significant. The northwest wind played an important role in migration and redistribution of leaves and fruits in Salix communities, so the northwest wind was main reason for the formation of three pattern of litter. These results might provide scientific basis for vegetation optimization layout and ecological reconstruction in wind-sandy area of northern China.

t:The circulation andmoisture flux characteristics atmiddle and lower levels during a continuous autumn rain process from October24 toNovember6 of2008 in Yunnan Provincewere analyzed. Results show thatduring thisweather process the western Pacific SubtropicalHigh at500 hPawentwest and was stronger than average, and the southwest air currents in front of the trough and in the periphery  ofSubtropicalHighwere beneficial towatervapor transportation toYunnan. Its influence systemswere the southwestair current in front of the trough, the low-level jet and shear line atmiddle and lower levels. Therewere plentiful vaporduring the continuous rain process atmiddle and lower levels. During the previous stage of the process themainwatervapor source in lower levelof tropospherewas in South China Sea and Bay ofBenga,l and during the later stage itwas in South China Sea. Thewater vaporwas convergence overYunnan during thewhole process, and the heavy rain occurred in the area ofdivergence ofvapor flux less than -32×10-7g·hPa-1·s-1·cm-2.