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本文对1985年8月下旬北部湾热带低压发展为台风的演变过程作了诊断分析。发现在台风的生成和加强的过程中,涡旋动能出现显著的加强和向下转移,最大涡度层和无辐散层明显下降.与此同时,暖心结构也逐步形成。这一过程与低层西南季风的增强北进,卷入台风环流中的过程密切相关。涡旋动能收支的计算表明,低压由于处在强的水平切变和垂直切变基流中,风场和温度场的不对称和暖心结构的形成,使台风获得正压和斜压不稳定能量,加之以积云对流为代表的次网格过程向涡旋运动输送能量,从而使低压发展为台风。台风的衰亡是由于登陆后低层偏冷气流的入侵和下部暖心结构的破坏,使台风只有纬向平均气流取得能量,不足以补偿摩擦耗散和位能通量的辐散,因而减弱为低压的。 相似文献
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三、关于热带天气尺度系统的研究1973年以来,我国广泛开展了对热带天气系统的研究,取得了许多有意义的研究成果。对于前十年的研究工作已有专文总结,这里主要总结1984年开展本课题研究以来所取得的科研成果。在过去研究的基础上,近年来对影响我国的各种天气系统进行了更深入的研究,除进一步揭露了若干新的事实外,着重研究了主要系统的结构特征和发生发展机制,同时提出了一些预报依据,这无论在学术上或应用上都有新的进展,尤其对于南海地区来说,一些研究成果起到填补空白的作用。 相似文献
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周智翔 《热带气象学报(英文版)》2009,15(1):1-12
On the basis of a comprehensive literature review and data analysis of global influenza surveillance, a transmission theory based numerical model is developed to understand the causative factors of influenza seasonality and the biodynamical mechanisms of seasonal flu. The model is applied to simulate the seasonality and weekly activity of influenza in different areas across all continents and climate zones around the world. Model solution and the good matches between model output and actual influenza indexes affirm that influenza activity is highly auto-correlative and relies on determinants of a broad spectrum. Internal dynamic resonance; variations of meteorological elements (solar radiation, precipitation and dewpoint); socio-behavioral influences and herd immunity to circulating strains prove to be the critical explanatory factors of the seasonality and weekly activity of influenza. In all climate regions, influenza activity is proportional to the exponential of the number of days with precipitation and to the negative exponential of quarter power of sunny hours. Influenza activity is a negative exponential function of dewpoint in temperate and arctic regions and an exponential function of the absolute deviation of dewpoint from its annual mean in the tropics. Epidemics of seasonal influenza could be deemed as the consequence of the dynamic resonance and interactions of determinants. Early interventions (such as opportune vaccination, prompt social distancing, and maintaining incidence well below a baseline) are key to the control and prevention of seasonal influenza. Moderate amount of sunlight exposure or Vitamin D supplementation during rainy and short-day photoperiod seasons, more outdoor activities, and appropriate indoor dewpoint deserve great attention in influenza prevention. To a considerable degree, the study reveals the mechanism of influenza seasonality, demonstrating a potential for influenza activity projection. The concept and algorithm can be explored for further applications. 相似文献
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本文分析了北半球盛夏期间澳大利亚冷高压强度与同期西太平洋低纬大气环流的关联,指出冷高压强度具有与南方涛动相联的准3—4年振荡,阐明了冷高压活动的年际变化对北半球低纬环流的影响与中短期冷空气爆发过程的区别。进而概括出冷高压强度与海气系统变化的相互关系。 相似文献
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本文对热带气旋移向突变进行了动力学分析,得到影响路径变化的主要因子,并在此基础上设计了一个诊断气旋移向稳定性的判据,经两百多次计算检验,证实其准确率达84％强。 相似文献
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