摘要
采用NCEP/NCAR再分析逐日资料,根据全型垂直涡度倾向方程,研究2005年6月华南强降水期间西太平洋副热带高压(副高)位置变动特征及其与加热场的关系。结果表明,西太平洋副高位置变化和副热带地区的非绝热加热有密切关系。与气候平均状况相比,2005年6月副高北侧的加热区很强,而南侧赤道辐合带(ITCZ)没有相当强度的对流;伴随着副高北抬,其南侧均有明显的对流潜热加热向北伸展。副高西侧的加热基本上都大于副高纬带内的加热,副高的每一次西伸都伴随着西侧加热的显著增强,并且加热增强先于副高西伸。对流层中层,副高北侧非绝热加热率的垂直变化基本上都大于气候平均值,不利于副高北进;而南侧加热率的垂直变化均小于多年平均,有利于副高南侧反气旋性涡度异常增长,从而有利于副高南退。2005年6月下旬副高西伸之前,副高西侧非绝热加热率的垂直变化基本上都高于气候平均状况,有利于副高西侧反气旋涡度增加,从而诱使副高随后西伸;而东侧加热率的垂直变化大多数时间都低于气候平均状况,使得副高东侧气旋性涡度增加,有利于副高西伸,对流层低层也具有类似特点。因此在南北两侧加热和东西两侧加热的共同作用下,2005年6月副高位置较常年偏南偏西,从而有利于雨带在华南地区维持。
Based on NCEP/NCAR daily reanalysis data, the position variation of the western Pacific subtropical high (WPSH) in June 2005 and its relation to diabatic heating are analyzed using the complete vertical vorticity equation. The results show that the position variation of WPSH is associated with the diabatic heating in subtropical areas. In comparison with June climatology, there were strong heating to the north side of WPSH and relatively weak ITCZ convection to the south side in June 2005. Along with the northward movement of WPSH, the convective latent heating extended northwards from its south side. The heating to the west of WPSH was generally greater than that inside of the WPSH, and each of significantly enhancements in the heating corresponded to a subsequent westward extension of WPSH In mid-troposphere, the vertical variation of heating rates to the north of WPSH was basically greater than the climatology, which is unfavorable to the northward movement of WPSH. On the other hand, the vertical variation of heating to the south of WPSH was mainly less than the climatology, which is favorable to the anomalous increase of anti-cyclonic vorticity, leading to the southward retreat of WPSH. Before the westward extension of WPSH in the late June 2005, the vertical variation of heating rates to the west (east) of WPSH was largely higher (lower) than the climatology, which is in favor of the increase of anti-cyclonic (cyclonic) vorticity to the west (east) of WPSH, inducing the subsequent westward extension of WPSH. There were similar features in lower troposphere. As a result, the heating to the north and south, the east and west of WPSH worked together to make the WPSH extend more southwards and westwards in June 2005, which is in favor to maintain the rainbelts in South China.
出处
《气象学报》
CAS
CSCD
北大核心
2009年第4期666-673,共8页
Acta Meteorologica Sinica
基金
国家重点基础研究发展计划项目(2004CB418302
2004CB418301)
江苏省气象灾害重点实验室项目(KLME060204)
关键词
华南强降水
西太平洋副高
非绝热加热
全型垂直涡度倾向方程
Heavy rain in South China Western Pacific subtropical high Diabatic heating Complete vertical vorticity equation