大尺度大气运动的浑沌形态

本文用一个确定的强迫耗散的八维非线性自治系统描述大尺度斜压大气的运动。在一定的热力强迫范围,流型演变显示出浑沌形态。随着热力强迫的渐变,发生了浑沌形态与周期形态之间的多次转换。在浑沌区内又清楚地显示出周期3和周期6的窗口。 流型演变的周期形态,相应于夏半年对流层上层副热带高压中心沿东西方向的周期的低频振荡。转为浑沌形态后,这种规则性的低频振荡即遭到破坏。这个副热带高压周期性东西振荡的建立与破坏的现象,与实际大气的观测事实十分相似。

CHAOTIC FORMS OF LARGE-SCALE ATMOSPHERIC MOTION

Using an eighth-order set of determinate, forced, dissipative, and nonlinear autonomous equations, which governs the dynamics of a quasi-geostrophic flow of the baroclinic atmosphere, the chaotic forms of large-scale atmospheric motion are investigated numerically. In certain ranges of the thermal forced parameters, the chaotic forms of the variations of the flow patterns are exhibited distinctly. Along with gradual change of the thermal forced parameter, trans-formation; between periodic and chaotic motion forms occur repeatedly.The windows of period-3 and period-6 emerge also in the chaotic regions. The periodic motion forms of the flow patterns corresponde to the periodic low-frequency vacillations of the subtropical high cells along the zonal direction during summer half year. After the transformation from periodic to chaotic form occurs, these regular vacillations are broken immediately. This phenomenon of the establishing and the breaking of the periodic low-frequency vacillation of the subtropical high cells along the zonal direction tallies with observational fact.