Comparative analysis of intensity changes between super typhoons Rammasun (1409) andDamrey (0518) during the period of entering the Beibu Gulf

Using conventional meteorological data and NCEP/NCAR 1o by 1o reanalysis data, the differences of intensity characteristics betweensuper typhoon Rammasun (1409) and Damrey (0518) were investigated during the period of landfall and entering the Beibu Gulf. Theresults show that (1) the rapid strengthening of the subtropical high, the monsoonal and cross-equatorial inflows, weak downstream zonal verticalwind shear, and high temperature in northern South China Sea were key factors of two super typhoons sudden strengthening. (2) Super typhoonRammasun has a path of crossing Qiongzhou Strait into the Beibu Gulf, which exhibit weak friction and slight intensity decreasing, andis favorable to maintain its super typhoon grade. In contrast, super typhoon Damrey crossed Hainan Island into the Beibu Gulf, leading to greatintensity decreasing. (3) The kinetic budget shows that kinetic friction dissipation caused by terrain is concentrated in the boundary layer (below800 hPa). Rammasun has a considerable decrease of kinetic energy after into the Beibu Gulf, while Damrey has greater kinetic dissipationduring the period of crossing Hainan Island.