Numerical Simulation On Sea Spray Enthalpy Flux Exchange During The Process Of Tropical Cyclone

Enthalpy flux plays an important role in ocean-atmosphere boundary layer during the process of Typhoon.It is indispensable for typhoon in terms of development and maintenance.However,there are still many uncertainties in the parameterization of the air-sea interface fluxes during a typhoon.As for the intensity of typhoon,the results of current numerical models are normally weaker than the observation values.Studies have shown that a large number of sea spray can be generated by the breaking of the waves existing at the surface of the ocean.These sprays can influence the heat flux on the sea surface layer through a series of physical processes,directly or indirectly contributing heat and energy to the development and maintenance of typhoons.So it is of vital importance for us to figure out interfacial enthalpy flux exchange during the process of Typhoon.Firstly,based on the current parameterization scheme of heat fluxes at the interface of the sea-air,the author reviewed the theory of heat fluxed parameterization and development process in terms of the oceanic spray heat flux at the air-sea boundary layer.Considering the features of spray fluxes,We figured out the physical process,input and output of WRF module ‘Surface Layer,and then we transplant the spray module to the WRF numerical model.Secondly,based on the WRF model with sea spray parameterization embedded in,by comparison between observation and simulation results,we utilize the super typhoon called ‘Megei' as an example to investigate the influence of sea spray on the typhoon's trace and magnitude.We perform this analysis from the perspective of Typhoon's structure and heat distribution.The experiment results demonstrates that the overall influence of sea spray on the Typhoon's trace is quite small while the simulation of the Typhoon's magnitude is improved concerning the influence of sea spray.This is because that the sea spray effect significantly increases the wind speed of the Typhoon,which further increases the vertical vorticity and promotes the vertical convection.As a result,the area of vertical vorticity extends higher,bringing moisture to upward layer,and this water evaporation promotes the interaction of sensible and latent heat flux at the air-sea surface.In addition,by analyzing the transfer of enthalpy between different high-wind areas,we find that the latent heat caused by sea spray evaporation is more intense in the area with higher wind speed.Finally,due to the lack of observational data,there is a great uncertainty in the parameters of the parameterization scheme for the boundary layer of the air-sea interface.Therefore,this paper compares the different values of commonly used parameters in the parameterization scheme of oceanic droplets heat flux.The paper discuss the different values of commonly used parameters in the parameterization scheme of oceanic droplets heat flux.And the result shows that : as for typhoon "Megi",spray fluxes are very sensitive to different sea surface roughness parameterization.However,it showed no sensitivity to sea surface heat and moisture parameterization.Furthermore,the effect of significant wave height on sea spray fluxes is also very obvious.