海洋飞沫方案改进对台风“威马逊”强度预报的影响

本文采用分粒径段组合方式改进海气耦合模式海洋飞沫方案,并利用耦合模式对1409号台风"威马逊"进行数值模拟,分析了海洋飞沫方案改进对台风结构、强度以及海气动量通量、热量通量模拟结果的影响。结果显示,耦合模式中海洋飞沫方案可通过改变海表面粗糙度影响海气动量与热量通量;海洋飞沫还可以通过沫滴向大气输送感热和水汽而直接影响海气热通量,进一步影响台风的强度。模拟结果显示改进后海洋飞沫方案的台风强度更接近观测。改进海洋飞沫方案后粗糙度的计算结果小于原始方案,相应地海气热通量以及下垫面耗散作用也弱于后者,海表面风场是海气热交换与下垫面耗散共同作用的结果。

ON TROPICAL CYCLONE INTENSITY FORECAST USING IMPROVED SEA SPRAY SCHEME IN REGIONAL ATMOSPHERE-WAVE COUPLED MODEL

A sea-spray parameterization scheme in tropical cyclone (TC) model was improved and it well performed at selected diameter domains.The super Typhoon Rammasun in 2014 was simulated to analyze the impact of the improved scheme on TC development.The TC structure,intensity,momentum flux,sensible heat flux,and latent heat flux were analyzed.The simulation result in the improved sea spray scheme was closer to the TC track.In the sea spray scheme,air-sea momentum and heat exchanges varied by changing sea surface roughness and droplet evaporation,the TC intensity and structure in the simulation were also changed,and the roughness was smaller than that in the original scheme.In addition,the sea surface wind was enhanced as the friction was weakened.On the other hand,the reduced roughness resulted in smaller sensible and latent heat fluxes and less energy supply for TC.The sea surface wind speed was controlled by the balance between friction mechanism and heat strengthening mechanism.