摘要
In this paper,the effects of sea spray on tropical cyclone(TC)structure and intensity variation are evaluated through numerical simulations using an advanced sea-spray parameterization from the National Oceanic and Atmospheric Administration/Earth System Research Laboratory(NOAA/ESRL),which is incorporated in the idealized Advanced Research version of the Weather Research and Forecast (WRF-ARW)model.The effect of sea spray on TC boundary-layer structure is also analyzed.The results show that there is a significant increase in TC intensity when its boundary-layer wind includes the radial and tangential winds,their structure change,and the total surface wind speed change.Diagnosis of the vorticity budget shows that an increase of convergence in TC boundary layer enhances TC vorticity due to the dynamic effect of sea spay.The main kinematic effect of the friction velocity reduction by sea spray produces an increment of large-scale convergence in the TC boundary layer,while the radial and tangential winds significantly increase with an increment of the horizontal gradient maximum of the radial wind, resulting in a final increase in the simulated TC intensity.The surface enthalpy flux enlarges TC intensity and reduces storm structure change to some degree,which results in a secondary thermodynamic impact on TC intensification.Implications of the new interpretation of sea-spray effects on TC intensification are also discussed.
In this paper, the effects of sea spray on tropical cyclone （TC） structure and intensity variation are evaluated through numerical simulations using an advanced sea-spray parameterization from the National Oceanic and Atmospheric Administration/Earth System Research Laboratory （NOAA/ESRL）, which is incorporated in the idealized Advanced Research version of the Weather Research and Forecast （WRF-ARW） model. The effect of sea spray on TC boundary-layer structure is also analyzed. The results show that there is a significant increase in TC intensity when its boundary-layer wind includes the radial and tangential winds, their structure change, and the total surface wind speed change. Diagnosis of the vorticity budget shows that an increase of convergence in TC boundary layer enhances TC vorticity due to the dynamic effect of sea spay. The main kinematic effect of the friction velocity reduction by sea spray produces an increment of large-scale convergence in the TC boundary layer, while the radial and tangential winds significantly increase with an increment of the horizontal gradient maximum of the radial wind, resulting in a final increase in the simulated TC intensity. The surface enthalpy flux enlarges TC intensity and reduces storm structure change to some degree, which results in a secondary thermodynamic impact on TC intensification. Implications of the new interpretation of sea-spray effects on TC intensification are also discussed.
基金
National Basic Research Program of China(973 Program)(2009CB421500)
Natural Science Foundation of China(40875039,40730948,40921160381)
Projects for Public Welfare(Meteorology)of China (GYHY201006008)
