Effect Of Sea Spray On The Sea-air Fluxes And The Upper Ocean Temperature During The Typhoon Passage

Firstly, the effect of sea spray on air-sea heat and momentum fluxes are completely introduced to improve the existing sea spray flux algorithm. On the macroscopical aspect, the momentum effect of sea spray is introduced into the parameterization of sea surface roughness for the full wind speed conditions. Variation characteristics of the drag coefficient with considering the impact of sea spray are consistent with the counterparts obtained from the observations. On the microcosmic aspect, both the sea spray feedback mechanism and comprehensive whitecap areal fraction are introduced into the sea spray flux algorithm developed by Fairall et al., which is more consistent with the real physical process.Secondly, based on above sea spray flux algorithm and KEO buoy observation, the effect of sea spray on the air-sea fluxes is investigated during typhoon Yagi passage. In addition, based on the ocean mixed layer diagnostic equation and one-dimensional GOTM turbulence model, the impact of sea spray on the upper ocean is further investigated. Results show that the air-sea heat exchange is enhanced obviously, especially for the latent heat exchange. The maximum of total latent heat flux is enhanced by 137.2W/m2, which is an increment of 15.7% compared with the interfacial latent heat flux. Meanwhile, there is a certain correlation between.the sea spray heat fluxes and wind speed as well as wave age; Besides, the air-sea momentum exchange is also enhanced by the effect of sea spray. When wind speed is larger than 30m/s, the sea spray momentum flux is comparable with the interfacial momentum flux. The regime of limiting saturation suspension layer is formed by the sea spray, which reduces the growth rate of total momentum flux. Diagnostic results show that the maximum of the temperature dropping rate has an increment of 1.22℃/d by the sea spray entrainment flux during the process of the thermal balance in the mixed layer, which is 84% of,the entrainment flux without the effect of the sea spray, and the maximum of the mixed layer deeping rate has an increment of 0.7m/d by the sea spray entrainment velocity during the process of the mass balance in the mixed layer, which is 6% of the entrainment flux without the effect of the sea spray. In short, the total entrainment fluxes in the mixer layer are enhanced through the momentum entrainment component induced by the sea spray, which further makes the mixed layer deeper and colder during the typhoon passage. Results from the GOTM turbulent model show that the turbulent kinetic energy above the 50m depth is enhanced by the sea spray when Yagi passes the KEO station, especially, the value of the turbulent kinetic energy is doubled near the sea surface.When the typhoon left the KEO station for two or three days, the enhanced turbulent kinetic energy cascades to spread downward to 75m depth. Therefore, the turbulent mixing near the sea surface is improved by the enhanced turbulent kinetic energy by the sea spray, which makes the vertical distribution of ocean temperature consistent with the actual KEO observation.Finally, based on the three-dimensional POMgcs ocean model, the effect of sea spray on the air-sea fluxes and the ocean upper temperature are investigated in the ECYB (East China, Yellow and Bohai) Sea region. According to the numerical results, the distribution of sea spray fluxes depends on the location and the local structure of the typhoon. The value of the sea spray fluxes almost is zero around the center of typhoon; The location of the maximum of sea spray fluxes lies right front of typhoon, consistent with the distribution trends of the wind speed and the significant wave height. Sea spray momentum flux enhances both the vertical diffusion and the advection process of the sea temperature, and sea spray heat fluxes mainly modulate the vertical diffusion of temperature only. When the impact of sea spray heat fluxes and momentum flux are taken into account together, the positive feedback process between them further affects the heat budget of the upper sea. In addition, the spray enhances the strength of the "cold suction" and "heat pump" during the typhoon passage. In the process of the "cold suction", the sea spray increases the value of the cooling in the 60m underwater corresponding to the typhoon center position.In the process of the "heat pump", the degree of both the cooling near the sea surface and the warming near the sea subsurface are improved. Compared with the case without the impact of sea spray fluxes, the maximum of the sea surface cooling induced by the sea spray is increased by 0.5 ℃ in the right side of the typhoon track, which is in accord with the actual satellite observations.