Based on conventional meteorological observation data of Zhejiang Province, ERA5 hourly reanalysis data (0.25°×0.25°) and blackbody brightness temperature (TBB) of FY-4A satellite, the two rainstorm processes occurring on June 3 and June 30 in 2020 were compared and analyzed. The results are as follows: (1) The rainstorm on June 3 (short for “6·03”) occurred in the background of monsoon trough, and there were southwest flow in front of the trough at 500 hPa and warm shear at 850 hPa over Zhejiang Province,while the rain storm on June 30 (short for “6·30”) occurred in the background of northeast cold vortex, there were confluence of cold and warm air at 500 hPa and cold shear at 850 hPa. For two rainstorm processes, their rainfall areas were similar, all concentrating in west Zhejiang and presenting east-west belt distribution. But for the “6·30” process, the rainfall area was wider, both the center rainfall and process rainfall were larger, the hourly rainfall intensity was stronger, and the duration of heavy rainfall was longer. (2) Both two rainstorm processes were convective unstable precipitation, but the heavy rainfall areas were in different positions of the jet stream. The “6·03” process was a warm shear type rainstorm in the warm region, the “train effect” of convective cloud clusters was significant and precipitation was located in the strong convergence area of water vapor flux in front of the jet. During the “6·30”, the Meiyu front was a westerly convergence frontogenesis, and the convective cloud clusters presented a backward propagation path, the precipitation was located in the strong convergence area of water vapor flux near the jet axis. The maximum convergence area of water vapor flux and intensity at 700 hPa corresponded to the falling area and intensity of heavy precipitation in the next six hours, which had a certain reference in rainstorm forecast in the Meiyu season. (3) Due to different precipitation types, the corresponding frontogenesis was different, and the height of the frontal zone indicating one hour heavy rainfall was also different. So in the forecast of rainstorm in the Meiyu season, the correspondence of different precipitation types and frontogenesis at different heights should be fully considered.

Based on GRACE (Gravity Recovery and Climate Experiment) satellite products, the TWS changes were calculated in drylands of northern China during the past two decades. And on this basis, the characteristics and causes of TWS changes were explored by using multi-source observations and model simulations. The results show that TWS in drylands of northern China decreased with a rate of 17.80±1.72 Gt per year during 2002-2020, which was also accompanied by various degrees of reduction in groundwater, root zone soil moisture and surface soil moisture. In drylands of northern China, the effects, such as climate warming and human water consumption, caused a substantial increase of evapotranspiration. The negative contributions of evapotranspiration overpassed the concurrently positive contributions of precipitation, and thus led to the decrease in TWS and increase in regional water stress.

Based on the ground intensive observation data, NCEP FNL reanalysis data, FY-2G satellite cloud images and dual polarization radar data, the influences of Typhoon Lekima (1909) on extreme heavy precipitation in the coast of Zhejiang Province were analyzed and discussed. The results show that the intensity of Typhoon Lekima was strong, the range was wide, and the intensity weakened slowly and movement was slow after the typhoon landing, which caused the extreme heavy precipitation in the coast of Zhejiang Province. The low values of black body temperature (TBB) matched with the centers of heavy rainfall for a long time, and the train effect and enhancement of southeasterly jet anticipated the amplification of heavy rainfall. The high value zones of ZH, KDP and ZDR of dual polarization radar were consistent, which indicated there were plenty of big water drops over the coastal areas of Zhejiang. The atmospheric precipitable water consistently maintained high-value with 70 to 80 mm over extreme heavy precipitation area, and the continuous and exuberant southwesterly and easterly jets transported water vapour to Zhejiang. Meanwhile, the center of positive vorticity coincided with the center of strong convergence in lower troposphere, and the height of convection development was very high, which were conductive to the amplification of heavy rainfall. Moreover, the vertical motion of apparent heat source (Q1) and apparent water vapor sink (Q2) was dominant. The peak value of Q1 and Q2 appeared alternately, and the corresponding height of the former was higher than that of the latter, which was beneficial to latent heat releasing and heavy rainfall maintaining.

According to the synoptic background and the evolution characteristics of radar echoes of a strong single hail event occurred in Yongdeng county of Uansu Province on July 8，2003，the jumping change of echo height，intensity and liquid water content，and the special structure features of the strong single hail were analyzed in this paper. 'hhc results show that the range and extension height of strong reflectivity area on vertical section arc important to hailstorm development.  While the strong reflectivity area is corresponding to bunbant  watea area In cloud，and only water content accumulating area being in the cooled 4km,region in the cloud can t0  abundant he benefit to hail development.  <)nec the echo intensity reached 55 dBz and its height was above hail falls immediately. 'hhe strong single hail with special structure developed very strongly.  Above conclusions
arc nificant to hail monitoring and prcwarning.

By using the lightning data in 2000 and 2002 around Lanzhou，lightning characteristics such as daily variation，spatial density，intensity and polarity of lightning are analyzed and also compared with those in Shandong province.The results indicate that major cloud-to-ground（CG）flashes of lightning are negative.The mean intensity of positive flashes is stronger than that of negative flashes and their ratio is over average during 12：00 to 00：00.Daily variety of the CGand negative flashes is bimodalundulance，other than positive flashes unimodal.The biggest flashes frequency center locates in Weiyuan and Longxi county，and accord with the location of hail source are aand hail affecting zone. Furthermore，the spatial distribution of lightning is closely related to the topography and under lying surface and synoptic climatic background