Simulation Study of the Diurnal Radiation Variation Impact on the Landfall Weakening Process of Typhoon

WEN Xiaopei; WU Wei

doi:10.16032/j.issn.1004-4965.2025.071

Abstract：The WRF model was used for numerical sensitivity simulations to analyze the influence of short-wave radiation diurnal variation on the landing and weakening stage of Typhoon In-fa(2106).The results show that the CTRL experiment successfully reproduced the weakening process of the typhoon.In the daytime experiment,the simulated typhoon weakened more slowly and wasmaintained for a longer time,Whereas it weakened rapidly in the nighttime experiment.Compared with the CTRL experiment,the daytime experiment had stronger short-wave radiation,leadingwhich led to increased surface temperature,latent heat flux from surface evaporation,and water vapor from the ocean to the atmosphere,keeping the lower atmosphere highly unstable.Sustained radiative heating and latent heat release in the middle layer produced strong vertical motion.Meanwhile,increased relative humidity in the upper layer promoted upper-level cloud formation,and upper-level stability decreased due to cloud radiative forcing.The continuous release of high-intensity latent heat prevented the breakdown of the typhoon's warm core structure,which is the main reason the typhoon intensity was maintained.In the nighttime experiment,however,surface radiative cooling reduced the energy supply to the lower layer.The typhoon thus released its unstable energy quickly,reached a stable state rapidly,and consequently weakened swiftly.