摘要
采用中尺度大气模式MM5和区域海洋模式POM构造了中尺度海气耦合模式,模拟了Krovanh(0312)台风过程中台风-海洋相互作用,分析了台风引起的海面降温影响台风强度的机制和海洋对台风响应的特征。试验结果显示:考虑台风引起的海面降温使台风强度模拟有了较大改进,模拟的台风中心气压和近中心最大风速均与实况较符合。POM模拟的海表面温度与TRMM/TMI观测的海表面温度也较为一致,台风Krovanh在其路径右侧95 km处引起较大的海面降温,最大降温幅度达5.8℃。与海表面温度降低相对应的是混合层深度的增加,较大的海面降温对应较大的混合层加深,表明大风夹卷在海表面温度的降低中起主要作用。分析表明,台风引起的海面降温降低海洋向大气输送的潜热通量和感热通量,特别是在台风内核区,平均总热通量减少了32.1%。热通量的减少使得湿静力能及湿静力能径向梯度减小,削弱了台风强度。
In order to investigate the mechanism of impact of sea surface temperature （SST） cooling on typhoon intensity and the ocean response to typhoon, a mesoscale coupled air- sea model is developed based on the non-hydrostatic mesoscale model MM5 （the fifth-generation Pennsylvania State University-National Center for Atmospheric Research Mesoscale Model） and the regional ocean model POM （Princeton Ocean Model）. In this study, two experiments are performed, one used the coupled model and the other MM5, in which the SST field at the model initial time is fixed so that the typhoon-induced cooling is ignored. Results reveal that the level of intensity prediction is improved including typhoon-induced SST cooling, the simulated minimum surface pressure and maximum surface wind in the coupled model are better consistent with observation than that in the uncoupled model, and the simulated central pressure from the latter is 20 hPa deeper than that from the coupled model result.
The SST simulated by POM in the coupled experiment is also in good agreement with that from the TRMM/ TMI-derived data. The maximum SST cooling is 5. 8℃, which is about 95 km away from the right side of the typhoon track. Corresponding to the SST cooling, the depth of mixed layer deepens in the meantime, indicating the effect of entrainment on SST cooling.
Analysis shows that SST cooling reduces the sensible and latent heat fluxes from ocean to the vortex, especially in the inner-core region. In this study, the averaged total heat fluxes in the inner-core region of the typhoon decrease by 32. 1%, which causes reduction of the moist static energy and the radial gradient of moist static energy, resulting in weakening of the typhoon.
出处
《大气科学》
CSCD
北大核心
2009年第1期99-108,共10页
Chinese Journal of Atmospheric Sciences
基金
国家自然科学基金资助项目40675065
40333026
国家重点基础研究发展规划项目2007CB411805
关键词
海气相互作用
台风强度
耦合模式
海面降温
air- sea interaction, typhoon intensity, coupled model, SST cooling
