副热带高压北跳与月尖(CUSP)突变

观测事实表明,大气在一个广泛的时空尺度中出现各类突变现象。本文以René Thom首创的突变论为工具,通过月尖突变模型讨论了副热带高压北跳这一大气突变现象,指出控制参数的渐变如何导致现象的突变,进而解释了大气环流的“(六月)突变”现象。文中还指出,由于行星尺度副热带高压的移行发展,有时与等压面位势高度场的变化直接相联,因而副热带高压未必是作为一个系统“实体”而移行发展的。     

NORTHWARD JUMPING OF SUBTROPICAL HIGHS AND CUSP CATASTROPHE

The observational facts show that over a wide range of time and space there exist in the atmosphere a variety of catastrophic phenomena. In this paper, the northward jumping of subtropical highs—a catastrophic phenomenon in the atmosphere—is diseussed on the basis of the catastrophe theory initiated by René Thom as well as the cusp catastrophe model; the mechanism of the gradual change of the controlling parameters leading to the abrupt change of the phenomenon is investigated and thus the well-known phenomenon of the "June catastrophe" of the atmospheric circulation interpreted.Also, it is pointed out, as sometimes immediately conditioned by the change of the geopotential values on the isobaric surface, planetary scale subtropical highs are not necessarily moving and developing as "realistic systems".     

THE GENERALIZED E-P FLUX OF WAVEMEANFLOW INTERACTIONS

This paper deals with the generalized E-P flux relation, containing the stratification effect and directly diagnosing the mean zonal acceleration from data. Its advantages are that the mean zonal acceleration may also be diagnosed, even if there is the strong baroclinity in the atmosphere and the heat transportion of the transient disturbances obviously varies with time and spsee. Meanwhile, both the ill-condition /(u'v')_y existing in the E-P flux and the terms correlative with the disturbance displacement η' not easily measured in Andrews' E-P flux are automatically eliminated in the generalized E-P flux. Therefore, it is suitable for directly diagnobing the mean zonal acceleration from observational data. In order to examine the applicability of the generalized E-P flux, it is illustrated that an example is correctly diagnosed by using the generalized E-P flux instead of the E-P flux.     

表征波与流相互作用的广义E-P通量

本文给出了含有大气层结效应的、并用观测资料可直接去诊断纬向平均流加速的广义E-P通量关系。它的优点在于,即使在大气斜压性较强,瞬变扰动的热量输送随时间和空间有明显变化的情况下,波对纬向平均流的加速作用也能较好地被诊断出来。同时广义E-P通量中,自动解除了过去E-P通量中存在的病态条件及扰动位移η’的不确定性,它能较准确地用观测资料去判别。文中用实例说明了广义E-P通量能诊断出一般E-P通量所不能正确诊断出来的结果。