作　　者： ; ; ; ;

机构地区： 中国科学院大气物理研究所

出　　处： 《气象学报》 2007年第2期198-207,共10页

摘　　要： 利用NCEP/NCAR1000—10hPa2.5°×2.5°日平均和每日4次再分析资料,分析了2003年6月19—25日热带对流层上空东风带扰动对西太平洋副热带高压东西向进退的影响。结果表明:热带对流层上空东风带扰动从对流层中低层伸展到50hPa高度附近,在200hPa上表现最为明显,在热力场上表现出“上暖强,下冷弱”的垂直分布特征。当西太平洋副热带高压南/北侧的东/西风带上的扰动在相向运动中抵达同一经度上时,对应于西太平洋副热带高压的异常东退。垂直涡度方程的诊断分析表明:在东风带扰动附近,涡度倾向效应贯穿于对流层整层到50hPa高度上,在200hPa高度附近表现最显著,当高层东风带扰动东/西侧的负/正变涡增强时,当东/西风带扰动在相向移动过程中,它们涡度倾向正值区在130°E南北打通时,西太平洋副热带高压出现突然东撤。涡度方程分析还表明,对于涡度倾向变化的贡献中,水平涡度平流的贡献最大、β效应的贡献最小;当东风带扰动附近的水平涡度平流和β效应增强时、且由β效应所引起的东/西风带扰动中的南、北风分量在130°E附近南北同相迭加出现“正压发展”时,有显著的正涡度增长,对应于西太平洋副热带高压的东撤。 By employing the NCEP/NCAR reanalysis data sets （1000 - 10 hPa, 2.5° × 2.5°） , the impact of the vortex in the easterlies （EV）over the tropical upper troposphere on the east-west direction movement of the subtropical anticyclone over the Western Pacific Ocean （WPSA） on 19 - 25 June 2003 are analyzed in this paper. It is shown that the EV spatially extended from 700 hPa upwards to about 50 hPa, reached the maximum intensity at 200 hPa, and thermally exhibited the vertical distribution character of ＂warmer in the upper level （100 hPa） of the upper troposphere and colder in the lower level （350 hPa）＂. The WPSA retreated eastward abnormally when the EV in the easterlies in the south side of the WPSA and the vortex in the westerlies （WV） in the north side encountered in the vicinity of the same longitude while they moved in the opposite directions. The diagnostic analyses of the vorticity trend equation show that in the vicinity of the EV the effect of vorticity trend term extended from the whole troposphere upwards to 50 hPa level, with its most prominent effect at 200 hPa level. The WPSA abnormally retreated eastwards when the negative/positive vorticity change rate in the east/west side of the EV enhanced, and at the same time the two positive vorticity trend areas in the west side of the EV and in the east side of the WV meridionally connected along 130°E during the process of their motion in the opposite directions. In the vorticity equation, the contribution to the vorticity trend from the horizontal advection term was the maximum, and the one from the Beta effect the minimum. It is also found that the enhancement of the horizontal vorticity advection and Beta effect, as well as the ＂barotropic development＂ of disturbance resulted from meridionally in-phase superposition of the south and north wind components in the easterlies and westerlies near 130°E are temporally in agreement with the anomalous retreat of WPSA.

关 键 词： 东风带扰动 西太平洋副热带高压 东撤 涡度方程

领　　域： [天文地球]