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中国东部海域中尺度海-气耦合数值模式的初步研究

Preliminary Research on Mesoscale Air-Sea Coupled Numerical Model over Seas in East of China

【作者】 文元桥

【导师】 黄立文;

【作者基本信息】 武汉理工大学 , 交通信息工程及控制, 2002, 硕士

【摘要】 由于大陆沿海和近海区域是大陆、大气和海洋的交汇地带,使得这一区域有着与其它区域不同的天气和气候特征以及独特的热力和动力学特性。这些特性也引起了海洋学家和气象学家的极大兴趣和关注。他们在长期的研究中发现,在大陆沿海和近海区域的大气和海洋之间的相互作用实际上是在多种中尺度范围(空间尺度:对大气,2-2000km;对海洋,1-1000km;时间尺度:对大气,10分钟到10小时的量级;对海洋,几秒到两个星期)内的热量和动量的相互交换。为了更好的研究这种具有中尺度特征的海-气相互作用以及海洋和大气在热量、水汽、动量交换过程中的相互影响和反馈机制,发展中尺度特征的区域耦合模式是十分必要的。 中国近海不仅陆架宽广,河口、海岸地形复杂,而且处于大洋西边界流西侧,著名的黑潮横贯黄东海区域。研究表明,中国近海和沿海区域的许多天气和海洋现象与中尺度海-气相互作用是密切相关的。本文选择了1995年3月的两个黄东海入海气旋为研究对象,利用Z-O方程结合数值模拟对气旋爆发性发展的机制作了深入的诊断分析。同时还讨论了气旋入海过程中的海-气相互作用现象。为了更深入的探讨气旋入海过程中的海-气相互作用的机制,本文还利用一个大气模式(LASG-REM)和一个海洋模式(ECOM-si)发展了一个中国东部海域的海-气耦合数值模式,并对模式进行了初步的试验。本文主要的试验内容和结论包括: 1.个例诊断分析与模拟在对LASG-REM进行了地形分辨率、陆面类型参数化、行星边界层(PBL)参数化方案中地面变量算法等进行了改进的基础上,利用改进的LASG-REM、借助Z-O方程对两个典型的黄东海入海气旋进行了诊断分析和数值试验。考查入海气旋演变为爆发性气旋的动力过程和入海过程水汽输送对后续气旋发展的影响,我们发现:在冷季大气斜压背景场产生的强温度平流和由积云对流活动产生的大量凝结潜热释放(增强了斜压能量转换)等的共同作用下,入海气旋变成有利的特定空间结构、以及地面地转相对涡度急剧增加时,气旋便出现爆发性发展。爆发性发展时凝结潜热释放需要的大量水汽主要来源于气旋入海过程中,并通过来自于南方的 中国东部海域中尺度海-气耦合数值模式的初步研究低层的水汽水平输送和水汽辐合以及海-气之间的潜热输送积累水汽。其中,当地海-气相互作用过程所积累的水汽起主导作用,它通过影响后续的凝结潜热释放在一定程度上制约了人海气旋是否会发展为爆发性气旋,这对海洋爆发性气旋的预报具有重要意义。该诊断分析和模拟实验的结果表明了气旋在入海阶段海-气相互作用的重要性,这为发展黄东海区域的海-气耦合数值模式打下了良好的理论基础。 2.耦合模式的设计和初步实验 选择中国东部海域,利用基于UNIX系统的管道通信技术,建立了一个基于 LASGAEM和 ECOM1 的区域耦合模式。耦合模式不仅具有双向耦合特征,还能够通过自动进程控制实现耦合信息的实时、同步交换。耦合模式的个例试验则验证了耦合技术的可行性、耦合模式运行的稳定性。个例试验结果的初步分析表明中国东部海域的大气和海洋在中尺度上存在着密切的相互作用。

【Abstract】 The coastal zones of the world’s oceans where land, air and ocean meet are known for both atmospheric and coastal ocean hydrodynamic and thermodynamic patterns which differ from those in other environment because of their weather and climate. The challenge of predicting the motion in the coastal ocean is of interest to coastal oceanographers and meteorologists. They found that the marine atmosphere and the coastal ocean actually exchange buoyance and momentum within the meso-scale spatial and temporal domains of both fluids, spanning two to two thousand kilometers and ten minutes to ten hours on the atmospheric side and one to one thousand kilometers and seconds to two weeks on the ocean side. Therefore, It is very necessary to develop an regional air-sea coupling numerical model in order to face the challenge of reconciling the apparent cause and effect, feedback coupling between the marine atmosphere and coastal ocean, as heat, moisture and momentum are exchanged, over a wide range of spatial and temporal scales of observed motion.The eastern coast of China is not only the west boundary of Western Boundary Currents, but also famous for its numerous embouchures and complex topography. Many researches show that the interaction of marine atmosphere and ocean is obvious and play an important role in the motion of atmosphere and ocean . In this paper, we selected two cases of March in 1995 to discuss the mechanism of two explosively developed cyclone over the Yellow and East China Seas and the effect of air-sea interaction in these development. We also used LASG-REM which is an atmospheric model and ECOM-si which is an ocean model to develop a regional numerical air-sea coupling model of China. The region which we selected is the seas in east of China . The purpose of developing our own coupling model is to investigate the mechanism of the interaction of marine atmosphere and ocean of Chinese coastal zones thoroughly. The main tests and conclusions of this paper are:1. Diagnostic analysis and simulation of cases At first, we improved LASG-REM in topographic resolution, land-use categories and physical parameters, as well as in planetary boundary layer (PBL) parameterizations. In PEL parameterizations, Surface-Energy equation which developed by Blackadar and bulk-aerodynamic parameterization of Deardorff are used. Then, we usedthe improved LASG-REM to diagnose the dynamical processes of the passing extra-tropical cyclone over the Yellow and East China Seas and its explosive development in order to test our improvement. Both the dynamical processes of a passing cyclone evolving into an explosive one over the Yellow and East China Seas and the incipient moisture transfer effects on the sequent development are investigated in dynamical diagnostics and numerical experiment frame. Results suggested that explosive development occurred as significant increase of surface geostrophic vorticity and favorable spatial configure forced jointly by strong temperature advection from baroclinic background in cold season and large latent heat release (enhanced baroclinic energy conversion) by cumulus convective. The large moisture fluxes are on the midway passing over seas and are collected by convergent process of moisture via low level from the South and latent flux from local sea surface. The later is major moisture source during moisture collection process and dominates, to a certain degree, whether the passing cyclone will evolve into an explosive one or not. This will play a significant role on the forecast of marine explosive cyclone.2. Design of numerical air-sea coupled model The coupled model is a two-way coupling model in which the exchanged information coming from atmospheric model (such as wind stress, sensible heat flux, latent heat flux ) and ocean model (such as SST) flowed into each other synchronously. The key technique of our scheme is the inter-process communications in UNIX. We used pipe which complied FIFO(First In and First Out) rule as the communicator to exchange the information of two models a

  • 【分类号】P732
  • 【被引频次】4
  • 【下载频次】237
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