A Study On The Numerical Simulation Of The Influence Of Air-sea Interation To The Intensity And Structure Of Soulik(1307)

Air-sea interaction is one of the main physical processes affecting the intensity and structure of typhoon.This work successfully simulated the entire process of the interacting between Soulik(1307)and the ocean by using high-resolution atmosphere-ocean coupling model(WRF-POM)and real atmospheric and oceanic conditions,and analyzed the mechanism of air-sea interaction in the condition of typhoon from different aspects.The cold wake weaked the typhoon by reducing a large amount of Air-sea heat flux.The adjustment of the lowest model layer's temperature(LMLT)can reduce the negative feedback of the cold wake,and the reduction is about 40%.By reducing the sensible heat flux and suppressing the evaporating of the precipitation,the influences of cold wake on the the LMLT resulted in the strongest cooling of the LMLT occur in the eye of typhoon.On the other hand,the cold wake promoted the formation of a stable boundary layer(SBL).The low-level radial inflow is enhanced by the suppressing on convective activity outside the eye wall,but the influence on the typhoon's intensity is limited.Numerical experiments show that the ocean heat content(OHC)has a great correspondence with the rate of typhoon's intensity change.High OHC is beneficial to the improvement of typhoon strengthening rate.It is found that the upper current on the right side of the typhoon path in the coupling test is significantly strengthened,which enhances the vertical shear near the maximum wind speed radius of the typhoon.The vertical shear causes the upwelling and turbulent entrainment in the deeper water,leading to the reduction of sea surface temperature.At the same time,due to the shallow mixing layer of the ocean cold core eddy,the vertical mixing caused by the typhoon lead to the more obvious cooling of SST.The ocean cold core eddy obviously inhibits the formation of sea surface water vapor,which weakens the heating effect of water vapor condensation in the middle atmosphere on the typhoon warm core,which is not conducive to the instification of the typhoon.Dynamic roughness and enthalpy roughness have different effects on typhoon's intensity and structure.Dynamic roughness suppresses the increase of wind speed by consuming low-level aerodynamic energy,which also weaks the negative feedback effect of cold wake and the convergence of low-level water vapor.In general,the typhoon's intensity is negatively correlated with the dynamic roughness.The simulated typhoon is the strongest when the roughness at high wind speed decreases as the wind speed increases.In addition,the dynamic roughness also has a great influence on the wind-pressure relationship of typhoon.When the roughness at high wind speed does not change with the wind speed,the typhoon's wind-pressure relationship is closely related to the observation.The enthalpy roughness mainly affects the exchange of sea air heat flux.When the enthalpy roughness is taken as a large value constant,it is most beneficial to typhoon reinforcement.At the same time,the response of the ocean to the typhoon has weakened the instification of typhoon.