摘要
对NCEP 1°×1°再分析资料进行分析表明,南海地区发展型和不发展型中层涡旋的结构特征有着明显的区别:发展型中层涡旋的中心涡度逐渐增大,并同时向高层和低层发展,其中低层辐合维持得较好;而不发展中层涡旋的中心涡度则逐渐减小,不再向高层发展,其中低层辐合维持得较差。对称性分析表明,发展型中层涡旋的水平风场和风速垂直剖面都具有良好的对称性,而不发展型的较差;发展型中层涡旋中心的风速垂直切变小,有利于对流层中上层暖心的建立与加强,而不发展型则相反。平衡性分析表明,发展型涡旋在对流层中低层的平衡性较好,涡旋维持着较好的风压平衡关系,有利于涡旋的发展;不发展型涡旋则较差。纬向剖面位涡异常分析表明,发展型中层涡旋的正位涡异常在增强的同时向上发展,涡旋处于持续发展的阶段;而不发展型位涡则相反,一方面强度在减小,另一方面没有向上发展,涡旋逐渐减弱。
Using the NCEP 1°×1° reanalysis data, several obvious differences of the structural characteristics of developed versus undeveloped mid-level vortexes are studied. First, the central vorticity of the developed mid-level vortex increases towards higher levels, while the undeveloped one decreases. The low-level convergence structure maintains well in the developed mid-level vortex, whereas the undeveloped one does badly. Second, on the one hand, according to symmetric analysis, the horizontal wind field and wind vertical section of the developed mid-level vortex are well symmetric while those of the undeveloped one are less symmetric. Meanwhile, weak wind vertical shear help the developed mid-level vortex establish a warm core in upper- and mid-levels of the troposphere. On the other hand, according to the balance analysis, better balance between wind and pressure is shown in the mid- and lower-levels of the troposphere of the developed mid-level vortex than in those of the undeveloped vortex. Third, positive anomaly of potential vorticity is enhanced and developed in the vertical direction of the developed vortex. However, the undeveloped vortex weakens with a weak positive anomaly.
出处
《热带气象学报》
CSCD
北大核心
2012年第6期829-837,共9页
Journal of Tropical Meteorology
基金
国家自然科学基金(40875026)
国家重点基础研究发展计划(973计划
2009CB421501)
公益性行业(气象)科研专项(GYHY200906008)
广东省自然科学基金(9451008019002863)共同资助
关键词
南海地区
热带气旋
发生发展
中层涡旋
结构特征
South China Sea area
tropical cyclone
genesis and development
mid-level vortex
structural Characteristics
