节点文献

台风海面风场的动力分析、四维同化及数值试验

Dynamical Analyses,Four-Dimensional Data Assimilation and Numerical Experiment for Typhoon Sea Surface Wind

【作者】 马艳

【导师】 张庆华;

【作者基本信息】 中国科学院海洋研究所 , 物理海洋学, 2000, 博士

【摘要】 台风是最具破坏性的海洋-大气系统。台风及其引起的沿海强风暴潮和海上巨浪不仅给沿海地区人民的生命财产造成严重的损失,而且对海上交通运输、军事活动、海洋工程和渔业都带来严重影响。准确的台风海面风场是获得比较真实的海浪、风暴潮等海洋现象的关键所在。由于不准确的海面初始场和台风海面风场数值模式中物理过程不完善等问题,模拟预报台风海面风场的精度达不到要求,极大的影响了海浪、风暴潮等海洋过程的模拟预报精度。因此获得准确真实的台风海面风场不仅对国民经济的顺利健康发展起到至关重要的作用,而且会很好地促进海浪、风暴潮等过程的研究。 中尺度大气数值模式MM5在灾害性天气的预报研究方面具有重要的地位,并在暴雨研究方面取得了成功。在本论文中,我们结合气象工作者和海洋学者在台风研究中的不同侧重点,耦合自由大气和边界层过程,考察海气相互作用对台风海面风场的作用,首次将MM5应用于台风海面风场的研究之中,这对台风海面风场的研究来说是一个新的起点。本论文在MM5中,将中国国家气象中心中期预报谱模式T63/T106分析和预报场与常规地面和探空观测资料相结合,合理调整模式参数(海面粗糙度等参数),建立了一套适用于中国区域的台风海面风场的模拟、预报系统。 本论文利用改造过的中尺度大气数值模式MM5对两个台风个例:9608号台风(HERB)和9711号台风(WINNIE)进行数值试验。对海面风场而言,海气热通量交换对海面风场发挥着重要作用。因此本论文研究海面热量通量交换对9608号台风的强度和中心位置的影响,这也是以前国内台风数值模式中疏于考虑的方面。最后将模式模拟风场用于波浪的模拟研究之中,考察模拟海面风场在海洋环境研究中应用的有效性;并与目前国内较先进的LAGFD-WIN海面动力风场模式对比,检验MM5在台风海面风场研究中的性能。研究结果表明,MM5较好的反映出台风特性,并且优于LAGFD-WIN海面动力风场模式结果。 在考察台风不稳定扰动特征时,我们区别于以往的本征值方法,利用中尺度二维扰动模式,由MM5提供9711号台风数值试验结果作为扰动模式的初始场,从动力学角度研究台风过程的扰动特征。 初始资料问题对台风模式的预报模拟精度来说是一个最大、最重要的问题。因 此改善、弥补模式初始场所造成的不足是本研究论文的重点工作之一。目前,在国 内关于MMS中的四维资料同化(FDDA)方案试验刚刚起步。在本论文中,我们成 功的启动MMS的四维资料同化方案:分析逼近和观测逼近。我们改造模式,同时 启动这两种逼近方法,充分发挥探空资料和地面观测资料各自的优越性*探索不司 尺度、不同类型的资料在台风海面风场的应用。尝试卫星高度计风场资料溶于MMS 中的同化方案中,这是本研究论文的另一个创新之处。 本文的主要结论是: (l)对两个台风个例:9608号台风(HE朋)和9711号台风(W删IE)进行了 控制试验(CNTL)研究,分析台风模拟过程的温度距平、海平面气压及海面风场 分布特点。研究表明,两个台风过程分别在不同高度上具有暖中心结构;模拟出的 两个台风环流都呈现出台风的非对称及涡旋型态,模拟出的台风强度令人满意。对 移动路径来说,对9608号台风过程,12h模拟台风路径误差为1.3个纬度,0.7个经度, 而24h的模拟误差则为 0.4个纬度,0.2个纬度;而对于9711号台风过程,其 12h模拟 台风路径误差为1二个纬度,1石个经度;24h路径误差为1.9个纬度,1.5个经度:36h 模拟路径误差为 3二个纬度,2.8个经度。我们认为,山于9711号台风过程不准确的 初始场,9711号台风模拟路径精度逊色于9608号台风过程的结果。 p)9608号台风过程中感热通量和潜热通量交换,在台风中心附近,热通量较 小,但在台风周围,存在热通量的高值压,随着台风强度的减弱,热量通量交换也 随之减小。在海面上始终是海水给大气提供热量。海面潜热通量总为正通量,并且 都大于相应时刻的感热通量,表明水汽通量对台风系统比感热通量更重要。在分析 热通量在不同下垫面演变特征时发现,感热通量在陆地下垫面上最大,其峰值出现 在下午Zh左右,在水陆交界处的次之,而在水域上的最小,对于潜热通量则是水域 上最大,陆地上最小。 o)应用9608号台风的模拟海面风场到海浪的数值模拟研究中,发现山于台风 海面风场分布的不对称性(在台风前进方向的右侧风速最大),也因此造成了海浪 有效波高分布的不对称性,同时在台风影响的右前方也传播得较远。随着台风海面 风场减弱,风浪能量也逐渐消耗,有效波高也逐渐降低。 K)在台

【Abstract】 Typhoon is the best destructive marine-atmosphere system. Typhoon, strong coastal storm tide and billow which are caused by typhoon not only bring severe loss for people lived in coastal areas but also have high effect on transportation and operation on the sea, marine project and fishery. Accurate typhoon sea surface wind is the key point to obtain true wave and storm tide. The prediction accuracy of typhoon sea surface wind still does not satisfy the demand because of untrue sea surface initial data and incomplete physical process in numerical model of typhoon sea surface wind. These affect greatly the simulation and forecast accuracy of wave and storm tide. It is very important and critical to obtain accurate and true typhoon sea surface wind for the favoring and fine development of economy, and it is good to accelerate the study of wave, storm tide and so on. The mesoscale atmospheric numerical model of PSU/NCAR (MM5) possess important status in forecasting disaster weather and get success in heavy rainfall, in this dissertation, combining the different emphasis on the study of typhoon between meteorology operators and marine researchers, coupling free atmosphere and the process of boundary layer and studying the effect of air-sea interaction on typhoon sea surface wind, we took the lead in applying advanced mesoscale atmospheric numerical model (MM5) in the study of typhoon sea surface wind. It is a new jumping-off for the study of typhoon sea surface wind. We combined the analyses and forecast of T63/T106(spectrum model) in the National Meteorology Center with conventional surface and sounding observation data, adjusted logically model parameters, for example, sea surface roughness and so on in MM5. Finally we established a simulation and forecast system for typhoon sea surface wind that is suitable for China Sea. We made use of improved MM5 and had numerical experiment on two typhoons: one is for 9608 Typhoon (HERB), the other is for 9711 Typhoon (WINNIE). The exchange of air-sea heat is important for sea surface wind because we aimed at studying sea surface wind. We discussed for 9608 Typhoon how the surface heat I. respectively. We thought the simulated route accuracy of 9711 Typhoon was lower than that of 9608 Typhoon probably because of untrue initial field of 9711 Typhoon. (2). For the sensible heat and latent heat exchange for 9608 Typhoon, the exchange of heat flux were lower value near the center of typhoon, but it showed higher value area around the typhoon. The heat flux tended to decrease accompanying the decline of the strength of typhoon. On the sea surface, sea always offered heat to atmosphere. The latent heat flux was positive value and higher than sensible heat flux of same time. This showed that moisture flux was more important to typhoon system than sensible heat flux does. We analyzed heat flux evolution character on the different landuse. We found sensible heat flux of land took on the highest value and the peak value appeared at 2 PM; the value of common boundary between water and land took the second place, the value of the sensible heat flux of sea was the lowest. For latent heat flux, the value of land was the highest and the value of land was the lowest. The net radiation flux showed remarkable diurnal variation character. (3). Applying simulated sea surface wind to the study of wave, we found that the

  • 【分类号】P732
  • 【被引频次】3
  • 【下载频次】882
节点文献中: