长波的垂直結构和它的移动与发展的关系

本文利用线性两层模式討論了对流层上部和下部扰动的发展和移动,以及它們之間相互关系。有以下主要結果: 1.一般常用的“溫度波落后于气压波,扰动发展”这一規則,对于超长波(波长大于10000公里)只适用于对流层上部,对于波长为7000公里左右的长波自对流层中部以上皆可应用,对于較短的长波整个对流层皆可应用。 2。当槽线或脊线随高度向西傾斜时,扰动的上层发展,下层阻尼;向东傾斜时,上层阻尼,下层发展;当时,上下层同时发展. 3.溫度波和高度波的移速可以不同,甚至方向可以相反;无論在上层或下层,当脊移进輻散区或槽移进輻合区时,扰动发展;当脊移进輻合区或槽移进輻散区时,扰动阻尼. 4.扰动的振幅和移速随时間而变,它不仅决定于基本流場的参数和扰动的波长,同时决定于扰动本身的上下結构. 5.周期性变化的稳定波在发展时期,其振幅的发展一天可达两倍半以上.因此日常所观測到的环流的巨大变化是否都属于一般所謂的西风带不稳定的現象值得深入研究.

THE VERTICAL STRUCTURE AND ITS RELATION TO THE SPEED OF MOVEMENT AND DEVELOPMENT OF THE LONG WAVES

With linear two-layer model the development and movement of long waves in the upper and lower part of the troposphere are studied. The main results are:1. The usually used synoptic rules-the disturbance develops, when the pressure wave preceeds the temperature wave-is valid only in upper troposphere for ultra-long waves (with wave ength of about 10⁴ km or larger); valid from middle troposphere upward for long waves of wave length of about 7000 km and valid for whole troposphere for long wave of comparatively shorter wave length.2. In the basic current with shear ,the upper part of the disturbance develops while the lower part,damps when the axis of the trough or ridge line tilts westward with height and the upper part of the disturbance damps while lower part develops when the axis tilts eastward with height. When the upper and lower part develop or damp simultaneously. 3. The temperature wave and pressure wave may travel with different speed and their direction of movement may even reverse. In the upper as well as in the lower layer, the disturbance develops (damps) when the ridge moves into the region of divergence (convergence) or the trough moves into the region of convergence (divergence). 4. The amplitude as well as the speed of movement of the disturbance varies with time. They depend not only on the structure of the basic current and the wave length but also on the vertical structure of the disturbance as well. 5. The periodically varied stable disturbances may increase or decrease in amplitude snore than 250% in one day during the stage of development. Thus the ordinarily observed large variation of circulation in westerly belt may not be a phenomenon of instability.