Comparative analysis of rainstorms caused by two typhoons with similar path deep inland

Typhoons Bolaven (1215) and Lingling (1913) were two typhoons that went directly north to hit Heilongjiang province and caused heavy rain. Both of them changed in the process of going north to the inland. The tropical cyclone yearbook, Fengyun cloud top brightness temperature data, conventional observation data and NCEP/NCAR reanalysis data were used for comparative analysis of the characteristics and precipitation differences between the two typhoons. The results are as follows. (1) The rainstorm processes of the two typhoons were both related to mesoscale frontogenesis in the typhoon circulation. The strong cold air intrusion promoted the strong frontal growth in the northwest frontal area of Bolaven.The deep ascending movement formed mesoscale convective zone and the precipitation intensity was high.Strong cold air made Bolaven denaturated fast and moved slowly. (2) Lingling had greater strength, deeper wet layers and greater specific humidity at lower levels as it travelled north to the same latitude.As only weak cold air spreading southward intruded into the typhoon circulation, Lingling became degenerated and moved quickly.The northern front of the typhoon center was weak, and the precipitation intensity and range were small. (3) The convective structure and precipitation intensity were significantly different: the east side of Bolaven cloud system weakened and dissipated, while the west side and north side interacted with the cold air to trigger convection.The structure of the Lingling cloud system was basically unchanged, and mesoscale convective clouds appeared in the center and the north of the center. (4) Bolaven process showed that the atmosphere had strong convective instability, the convection was active in the rainstorm area, and the duration of heavy precipitation was long.When Lingling moved north, there was only weak convective instability in the lower layer, which was weak, and the duration of heavy precipitation was short.The convective instability in the lower layer and the symmetrical instability in the middle layer of the rainstorm area were conducive to the maintenance and development of heavy precipitation.