Based on the conventional observational data, satellite cloud images, radar echo data, automatic weather stations rainfall and NCEP/NCAR reanalysis data (0.25°×0.25°), the mesoscale features of a heavy rainstorm by the residual circulation of Typhoon Haitang in the northern part of Northeast China from 3 to 4 August 2017 were analyzed. The major conclusions were as follow:The residual circulation of typhoon had been strengthened again after it was moved into Northeast China. The negative pressure center on the ground was located at the inverted trough shear on the north side of the cyclone. The rapid development of cyclone and the enhancement of the convergence of the variable pressure wind resulted in the lower level convergence and heavy rains. The zonal distribution in the rainstorm area showed a tendency to increase northward, and there were obvious mesoscale features in the space-time distribution. Precipitation had the characteristics of strong intensity, sudden strength and short duration. The rainstorm zone was linear, with a horizontal width of 50 km and a length of 300 km, which had typical characteristics of the mesoscale-β. The sounding analysis showed that the atmosphere was in an unstable state, which was advantageous to the convection development with short time heavy rainfall. Heavy rains were caused by the mesoscale convection systems (MCS) activities. Each time the heavy precipitation was corresponding to the black body temperature (TBB) low value center, and the delay was about 1 h. In the process of convective cloud spreading from south to north, heavy rain occurred mainly in the area of cold cloud area or the TBB gradient at the posterior edge of the cloud cluster. The backward propagation of radar echo caused the strong echo activity in the rainstorm zone, and the precipitation lasted for a long time. Heavy precipitation was a warm cloud precipitation which led to high precipitation efficiency and strong rainfall. The mesoscale convective system which caused torrential rain, had a deep vertical motion. The deep vertical motion strengthened the lower layer heat and water vapor transmission. The positive vortex column of middle and lower level was enhanced rapidly, and the water vapor convergence was enhanced, which strengthened the development and duration of mesoscale convective systems. The middle and upper layer had dry air activity, which not only triggered convection, but also greatly reduced the atmospheric stability and provided favorable conditions for the occurrence and development of convection.

Typhoon Noguri(0801) caused a torrential rain event after landfall at East Hainan and West Guangdong. Based on the observational data, NCEP reanalysis data and the kinetic energy budget of divergent wind, the large-scale circulation and the transfer of kinetic energy were analyzed. The results show that: The heavy rain event is the result of the interaction between the Noguri remnant and its environmental systems. The strong low-level southeastern jet from the West Pacific together with the weakened southwestern jet linking with Typhoon Noguri after landfall keeps the strong transfer of moisture to the east of Guangdong, and the variation of kinetic energy of divergent wind indicates the details of the process. The convergence effect of kinetic energy flux which is induced by the variation of the intensity of low-level jets and the convergence fields, is the main source of kinetic energy of divergent wind over the heavy rain band. Furthermore, the updraft of warm air in southeaster jet and the downdraft of cold air in southeastern jet result in the transfer of baroclinic available potential energy to kinetic energy of divergent wind. Cold air plays an important role in the two processes. Besides, the variation of heavy rain between the East Guangdong and near the landing site is mostly due to the difference of the atmospheric stratification, even though the low level divergence is close within these two places.

In September 2016, Typhoon Meranti, the strongest recoded tropical cyclone to date 2016 made landfall over the city of Xiamen, China which caused great disaster. A comprehensive examination of Typhoon Meranti (2016) development and evolution processes, precipitation derived from the Integrated Multi-satellitE Retrievals for GPM (IMERG) algorithm and three dimensional structure and characteristics of cloud systems in the typhoon eye and the outer spiral rain bands on the ocean is studied by combination of Himawari-8, CloudSat and Global Precipitation Measurement (GPM) satellite high resolution data. The results reveal that there is a small and clear circular typhoon eye during the super typhoon stage. The distribution of total 24 hour typhoon precipitation exists heterogeneous and asymmetric structure and the maximum precipitation is located near the center of Typhoon Meranti. Measurements form the CloudSat level 2 cloud scenario classification product reveal that the eye wall and spiral cloud bands of Typhoon Meranti appear in the presence of deep convective cloud system and near the cloud top is cirrus and altostratus cloud. Above the 4 km height, there is discontinuous bright band and vigorous cloud system developed upper the bright band from the CloudSat level 2 Geometrical Profile (GEOPRO) product. The CloudSat and GPM satellite onboard radar see very tall convective hot towers at eye wall of Typhoon Meranti. Estimates precipitation from GPM DPR level-2A product indicates a maximum 295 mm·h^-1 precipitation rate which is located in the northeastern side of Meranti's eye wall. The vertical profile of radar echo intensity and latent heat from the spectral latent heating algorithm shows asymmetric distribution between eye walls from the GPM satellite. The maximum of 57 dBZ radar echo intensity, 17 km radar echo top and 88 K·h^-1 latent heat rate in convective hot towers at eye wall on the right side of the eye is observed by the GPM satellite where warm cloud microphysical processes is dominated in this area.

Numerical simulation and terrain sensitivity experiments on the heavy rainfall caused by the typhoon Nesat during 29-30 September 2011 were studied using the weather and research forecast(WRF) model when Nesat made the landfall and went through the north Hainan Island. The results show that: The rainfall caused by the westing typhoon landfall on the north area distributed more in the north than the south. In the north, there is more rain in the west area than east area. 48 h and 3 h accumulative rainfall from the 12 km experiment are successfully modeled and the landing time and location is close to the observed. The typhoon track and intensity are good simulated as well. The terrain sensitivity experiment shows that 24 h precipitation from the experiments with terrain have increased generally by more than 50 mm in the west area in Hainan Island. Increase of more than 150 mm has been observed in the western mountainous regions, with 350 mm increase in the north part of the main peak. Heavy precipitation center is found responding to main mountain peak, It proves that, the terrain can result in general obvious rainfall increase in typhoon. However, there is a 50~150 mm rainfall reduction in the eastern coast of the island due to the block from the Wuzhishan Mountain. Analysing the comparison of low-level mesoscale flow field and the vertical velocity, significant difference can be found between control experiments and experiment with none terrain. The Wuzhishan terrain can enhance low-level disturbances, which can easily produce the vortex of mesoscale convection (MCS), then by increasing the typhoon rainfall. The special terrain of Wangxia plays an important role in increasing the typhoon rainfall.

A heavy rainfall event that occurred in Shandong Province on 17-19 July 2008 was caused by the interaction between typhoon Haiou and westerly trough. The water vapor and the activities of dry and cold air of this heavy rainfall event were studied by using routine observation, NCEP/NCAR 1°×1° reanalysis and simulated data from the WRF3.2 model. The results show that the water vapor convergence was mainly from the inflow of the southern boundary. The intensification of the inflow of the water vapor from southern boundary primarily contributed to the northward transportation of water vapor from the typhoon. The convergence of water vapor in the west and middle parts of Shandong Province resulted from the vortex in the lower troposphere. The convergence of water vapor in the south-north direction corresponded well with rainfall. Dry and cold air apparently intruded into rainfall area in the process of the rainfall. In the initial phase of the heavy rainfall, dry and cold air in the tropopause first intruded into the rainfall area and induced the acceleration of west wind in the high levels and the enhancement of divergence, which led to the development of upward motion. In the development phase of the heavy rainfall, dry and cold air in the middle troposphere (500 hPa or 600 hPa) intruded into rainfall area with westerly wind from northwest to southeast and met with warm and moist air, resulted in upward motion. In the heavy rainfall period, dry and cold air came not only from northwest in the mid-latitude but also from the high latitudes. Dry intrusion in the higher levels was always ahead of that in the lower levels, which is favorable to the development of potential instability. The activities of dry and cold air as well as warm and moist air intensified frontogenesis in the lower and middle levels in Shandong Province and ageostrophic ascending motion was triggered, which is one of the mechanisms of the intensification of the ascending motion. Convective instability and conditional symmetric instability existed in the heavy rainfall event. Dry intrusion can slant the equivalent potential temperature surface and force warm and moist air to move upward slantwise along front, which is beneficial to the development of conditional symmetric instability.

Based on conventional ground data, typhoon best track from Shanghai Typhoon Institute, sounding data, black body temperature equivalent (TBB) of FY-2 meteorological satellite from National Satellite Meteorological Center, and high-resolution NCEP/NCAR global reanalysis data, the physical development mechanism and strong precipitation mechanism in Northeast China during typhoon Lionrock (1610) merging into extratropical cyclone process was analyzed. The result indicated that symmetric tropical cyclone cloud system developed into asymmetric baroclini cloudsystem, and finally evolved into mature extratropical cyclone cloud system. Meanwhile, Lionrock entered into the strong vertical wind shear environment gradually, and typhoon vortex circulation, water-vapor transfer and vertical movement showed remarkable asymmetric and vertical westward tilt feature. Furthermore, warm-core structure was destroyed, water-vapor transfer gradually went away from typhoon circulation. Under the interaction between upper and low-level jet, extratropical cyclone appeared obvious frontogenesis for the positive vertical vorticity advection, which enhanced the development of extratropical cyclone. Under the co-effect of Lionrock and extratropical cyclone, enhanced dynamic, water vapor and energy transport caused by development cyclone, was the main reason for the heavy rain in northeast China. It was found that precipitation in Northeast China mainly occurred in warm advection, high value of thickness gradient had good direct a indicative function. It was also found that heavy precipitation was influenced by strong upper levels divergence and low levels convergence of dynamic and water vapor, meanwhile corresponded to strong temperature advection and vertical upward motion. Long time duration of rainfall and ending slow, was related with weak dry cold air intrusion from high to low level slowly. The precipitation process was sustainability, with relatively strong convective precipitation occurring locally.

By using the data of routine aerological sounding, surface observation data and reanalysis data with 1°×1° every 6 hours, the remote typhoon rainstorm happened on 17 and 18 September 2011 in Shaanxi were analyzed. The results show that the typhoon is the leading system for this rainstorm process. Firstly, the typhoon and Western Pacific subtropical high block the eastward shift of the westerlies, and make Shaanxi in central and southern Influenced by southwest warm airflow for a long time. And this is a favorable circulation background for the formation of a wide range of heavy rain. Secondly, the wave excited by remote typhoon propagation to Chinese mainland,meets the mid-latitude low pressure systems and interact each other. It induces a moisture channel for the rainstorm, with the jet interaction and induced secondary circulation, and provides enough water vapor, energy and dynamic lifting for the rainstorm. Thirdly, the surface front is the trigger mechanism for rainstorm. The warm air that typhoon transmission through the wave meet the cold air over Chinese mainland. That produces frontogenesis and makes the precipitation strengthen.