摘要
随着大气探测技术的发展 ,登陆热带气旋研究已经成为热带气旋研究中一个新的领域。新的探测技术能初步揭示出热带气旋登陆过程中发生的多种改变。近年来 ,国内外科学家实施了一系列外场科学试验 (Fieldscientificexperi ments) ,对登陆热带气旋进行探测和研究 ,旨在提高预报的准确率。登陆热带气旋研究内容包括 :海岸和内陆山脉地形影响 ,结构和强度变化 ,登陆热带气旋的暴雨强度和分布 ,大风强度和分布 ,风暴潮强度和范围 ,登陆热带气旋在陆上的维持机制 ,陆地涡旋的路径和入海加强 ,边界层结构 ,陆面过程和能量交换 ,变性过程等。研究采用外场科学试验与数值模拟相结合的方法。模拟或预报模式中使用同化资料尤其是卫星同化资料来构造初值场 ,取得较好结果。登陆热带气旋的研究目前正在展开 ,并取得了一些重要结果。研究表明 ,潜热释放和斜压位能释放是近海或登陆热带气旋加强或维持的两种主要能源。这两种能量可分别从水汽输送和热带气旋与中纬度环流的相互作用中获得。另外 ,陆面饱和湿地或水面的潜热输送、热带气旋与中尺度涡旋或热带云团的合并以及高空流出气流强辐散也对其加强和维持有利。世界气象组织的热带气象研究计划 (TMRP)正在组织对这一领域的总结和下一步的研究计划。
Most prominent structure change of a tropical cyclone in its life span would appear in the period of its landfall process. Topographic forcing plays an important role for the tropical cyclone structure change when it's making landfall. Apart from the topographic forcing, structure change of a landfalling tropical cyclone also can arise from the interaction between the cyclone itself and some peripheral mesoscale vortices or a mid-latitude westerly trough. The structure change of a tropical cyclone often give rise to its intensity change, track turning and rainfall enhancement etc. On the other hand, the occurrence of most severe damages is due to those high impact weather such as high winds, heavy rainfall and strong storm surges associated with the landfalling tropical cyclones. Research community around the world attach more importance to the area of tropical cyclone landfall process in last ten years. Several scientific field experiments related to those tropical cyclones in the coastal water or over land are being implemented in the different region of the world. The title and its acronyms are as follows: TOST (THORPEX Observational System Test) in the eastern coast of US, CBLAST (Coupled Boundary Layer Air-Sea Transfer)-US, ATCCIP (Australia Tropical Cyclone Coastal Impacts Program), DOTSTAR (Dropsonde Observation for Typhoon Surveillance near the Taiwan Region), CLATEX (China Landfallling Typhoon Experiment). One of the common scientific objectives of those field experiments is to improve the tropical cyclone forecasting accuracy. Research programs are being carried out on the tropical cyclone landfall process. Some observational studies indicated that some tornadoes spawned in the right front quadrant of the typhoon after its landfall. Others find some mesovortices generated in the rainband of a tropical cyclone. Those structure changes would affect the behavior of the tropical cyclone including its high winds and rainfall intensity and distribution. Numerical simulation indicates that the moisture transportation is a favorable condition for the intensification of a tropical cyclone in the region of coastal water. Moisture transportation and latent heat transfer from the inland water surface or saturated wet ground are also favorable to landfalling tropical cyclone sustaining over land. Upper level strong divergence field or out-flow channel and small vertical shear or merger with some peripheral meso vortices (MSV) would be helpful to tropical cyclone intensifying in the off shore water or sustaining over land. Those processes provide latent heat energy to tropical cyclone which are also helpful to increase heavy rainfall of a landfalling typhoon. On the other hand, strong cold wave and oceanic stratification would be helpful to fill up or decay the typhoon. Extratropical transition process is another channel for storm to gain the new energy-baroclinic potential energy from the mid-latitude which is the result of the interaction between the tropical cyclone and the mid-latitude systems. ET process will convert the baroclinic potential energy into the kinetic energy to strengthen the circulation of the remnant low of the landfalling typhoon.
出处
《气象学报》
CAS
CSCD
北大核心
2004年第5期541-549,共9页
Acta Meteorologica Sinica
基金
国家自然科学基金 ( 4 0 175 0 19
40 3 3 3 0 2 8)
国家科技部公益项目 ( 2 0 0 1DIA2 0 0 2 6)
