In order to study the characteristics of typhoon precipitation and typhoon core precipitation in East China and the influence of large-scale circulation on the distribution of typhoon core precipitation, this paper uses the daily precipitation data from the National Meteorological Information Center and reanalysis data from NCEP/NCAR (National Centers for Environmental Prediction/National Center for Atmospheric Research), applies the dynamic synthesis analysis method, compares and analyzes the large-scale circulation characteristics of two types of typhoons (The L-type and the R-type core precipitation typhoons) with different distributions of precipitation during typhoon landing. The results are as follows: (1) Typhoons mainly landed in summer in East China, and the times of typhoon landing and extreme precipitation caused by typhoon had the characteristics of “single-peak mode” in monthly distribution. The precipitation gradually decreased from coastal to inland, from south to north. (2) The precipitation in the typhoon core was asymmetrical, and the heavy precipitation was more likely to occur on the side with the coordination of divergence and convergence field and the better maintenance of ascending motion. (3) The L-type core precipitation typhoon was mainly controlled by warm advection. There were multiple cold advection centers in the west of circulation. Cold and warm advection intersection enhanced the atmospheric convective instability and provided unstable energy for precipitation. R-type core precipitation typhoon was mainly controlled by cold advection after landing. In the northeast of circulation there were warm advections, and the atmospheric stability dropped due to the cold and warm advections interaction. It was beneficial to precipitation on the right side of the path. (4) Strong water vapor convergence existed in the southwest of the L-type core precipitation typhoon, which was conducive to the occurrence of precipitation on the left side of the path. During the landfall of R-type core precipitation typhoon, the water vapor convergence center maintained for a long time in the northeast of the circulation, which was conducive to the occurrence and development of precipitation system on the right side of the path. Divergence and convergence configuration in high and low level, cold and warm advection and water vapor transport were the main factors to affect the precipitation distribution in typhoon core.
The thermal and dynamic processes of the convective boundary layer over the Tibetan Plateau (TP) have an important impact on weather and climate of the downstream region and even the entire East Asia region. This paper uses a summer case of 2017 as an example to analyze the applicability of three sets of reanalysis data including ERA-Interim, JRA-55 and MERRA-2 in the study of the boundary layer over the TP, and further uses the constraints of the numerical model physical framework to correct its analysis error. In the summer of 2017, the variation of air temperature and dew point temperature were presented well through the three sets of reanalysis data in the boundary layer over the southeastern TP, while the reproducibility of the horizontal wind field was very poor, and the reanalysis data with better applicability over the TP during the study period was ERA-Interim. The results from the 12 parameterization scheme combinations selected in this paper were compared by the dispersion degree of the horizontal wind field error, improvements of the simulations in clear skies and moderate rain were significant. Therefore, for the simulated critical physical quantity (the horizontal wind field), the combination of Betts-Miller-Janjic, WSM6 and ACM2 scheme was the most locally applicable in the study area. The wind field in the reanalysis data could describe the summer boundary layer development over the TP more closely after adjustment using simulation results. It was proved that the model parameterization scheme could reduce its deviation of seasonal distribution in the plateau area, which had certain guiding significance for subsequent research and application.