Abstract:

Using the conventional observation data, tropical cyclone dataset data from China Meteorological Administration, the 1°×1°reanalysis data of NCEP every six hours and FY-2G temperature of brightness blackbody (TBB) product, the precipitation distribution characteristics caused by "Hagupit" and "Lekima" at Wenzhou airport, the characteristics of environmental field and the physical field causing the difference precipitation are analyzed. The results show that: The influence periods at Wenzhou Airport of "Hagupit" and "Lekima" are different. The "Hagupit" precipitation is concentrated before and after the landing, which is caused by the precipitation of the typhoon itself. The precipitation of "Lekima" is concentrated before the landing, mainly caused by the precipitation carried by the spiral rainband around the typhoon; The low-level jet and the shallow water vapor transport channels provide water vapor and energy for typhoon, and the variation of water vapor flux divergence at 925 hPa has a good corresponding relationship with typhoon rainstorm.Long-term convergence of strong water vapor flux can lead to the continuous enhancement of rainstorm.Compared with "Lekima", the long-term convergence of strong water vapor flux in the shallow layer during the landing of "Hagupit" is the main reason for the long-term heavy rainfall; The dynamic mechanism of high-level divergence and low-level convergence combined with the shallow vertical upward movement is beneficial to the intensification of typhoon precipitation. The dynamic mechanism of "Hagupit" is more powerful and stable than "Lekima", which is the important reason for the difference precipitation between the two typhoons; On the structure of TBB cloud, during the influence period of "Hagupit" the overall cloud cluster structure was symmetrical and compact, and precipitation was mainly affected by its ontological cloud cover, while the precipitation of "Lekima" is mainly influenced by its outer spiral cloud belt. The heavy rain period of airport is related to the coverage of the clouds with TBB ≤-70 ℃, and the long coverage of TBB≤-70 ℃ clouds during the period of "Hagupit" is the direct reason for the stronger precipitation than "Lekima".

Key words: Heavy precipitation difference, Water vapor transport, Dynamic mechanism, TBB