中尺度海-气相互作用对台风暴雨过程的影响研究

THE EFFECTS OF MESOSCALE AIR SEA INTERACTION ONHEAVY RAIN IN TWO TYPHOON PROCESSES

中文关键词:  海-气相互作用，台风暴雨，中尺度耦合模式

英文关键词:Air-sea interaction, Numerical simulation, Typhoon heavy rain, Mesocale Coupled Model.

中文摘要:

      利用中尺度海-气耦合模式MCM对两个典型台风过程进行了数值模拟试验，定量地分析了海-气相互作用对台风暴雨的影响，并探讨了这一影响的物理机制。结果表明，模式MCM 能成功模拟台风的路径、强度以及台风暴雨的落时、落区。考虑海-气相互作用能使台风中 心气压48和72 h分别回升9.9和3.5 hPa，使后续时段的台风对流性降水减小40～100 mm，还 明显改变了非对流性降水分布。耦合与非耦合试验对比分析初步表明，海-气相互作用影响 台风暴雨的机制是一种通过台风大风区附近海平面温度(SST)下降来调节的负反馈机制。

英文摘要:

      Two representative typhoon processes are simulated using a Mesoscale Coupled air-sea Model (MCM). The quantificational effects of air-sea interaction on heavy rain and physical mechanism are analyzed and investigated in details. MCM is a two-way interactive mesoscale coupled model that linked two component models (i .e., LASG-REM or MM5 and ECOM-si) together via Unix's process communication te chnique and coupled object modules. The lower boundary of the atmospheric model is forced by SST which is produced by ocean model and the upper boundary of ocea nic model is forced by sensible heat flux, latent heat flux, net long-wave radiation and net short-wave radiation flux which are predicted from atmospheric model. The coupling is active both from 23°N to 41°N and from 116°E to131°E, and information exchange is in two-way over a time step of ocean model. Experime nts indicate that typhoon track, intensity, rainfall time, distribution and rain fall intensity are better simulated by MCM. Due to air-sea interaction involved in MCM, the intensity errors are decreased by 9.9 hPa at 48h and 3.5 hPa at 72 h, accumulative convective precipitation decreased by 40-100 mm for 24 h and the distribution of non-convective precipitation improved significantly. A potenti al mechanism that air-sea interaction impacts on typhoon heavy rain is a negati ve feedback regulated by SST reduction: Wind stress induces vertical mixing, leads to SST decrease, results in heat flux decrease and lower level cooling of atm osphere, weakens ascent motion, inhibits convective activity and rainfall via cloud physics, weakens typhoon intensity and maximum surface wind, feedbacks to ocean and then slower SST decrease, finally forms a negative feedback process.