On the Structure of Medium-Scale Depressions over the East China Sea during AMTEX'75
On the Structure of Medium-Scale Depressions over the East China Sea during AMTEX'75
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AMTEX75期间东海中型凹陷结构研究
DOI：
10.2151/jmsj1965.55.3_286
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发表时间：
1977
影响因子：
3.1
通讯作者：
N. Saito
中科院分区：
文献类型：
--
作者：
N. Saito
通过对AMTEX'75期间东海形成的3个中型凹陷的分析，得出以下特征：（1）中型凹陷是浅层扰动，暖核低于700mb。 (2) 低压被认为是在东海产生的。然而，当预先存在的约 850 mb 的气旋涡旋从大陆移过海洋时，海平面气旋就开始了。 (3)系统的强化程度在最底层最大,且加深程度随着高度的增加而迅速减小。 (4)大范围锋区形成的凹陷。上述特征表明，最低层变暖是海平面中等规模凹陷形成的主要因素。使用厚度趋势方程评估1000mb至500mb之间三层的热平衡。评估结果表明，以下三个同时发生的动力过程是其形成的原因：（1）暖空气平流； (2)向上运动，小绝热冷却； (3)最低层视热源。有时，这样一个浅层系统似乎会发展成一个强大的气旋。这归因于天气尺度扰动的发展，而不是中尺度低压的自身发展。
From the analysis of three medium-scale depressions which formed over the East China Sea during the AMTEX '75, the following characteristic features were drawn: (1) The medium-scale depression was a shallow disturbance with a warm core below 700mb. (2) The depression was thought to generate over the East China Sea. The sea-level cyclogenesis, however, commenced when a pre-existing cyclonic vortex at about 850mb moved over the sea from the continent. (3) The intensification of the system was largest in the lowest layer, and the deepening rapidly decreased with height. (4) The depression formed in the largescale frontal zone. The above-mentioned features suggested warming in the lowest layer was a primary factor for formation of sea-level medium-scale depression. Heat balances in the three layers between 1000mb and 500mb were evaluated by using the equation of thickness tendency. The result of evaluation showed the following three simultaneous dynamical processes were responsible for the formation: (1) warm air advection; (2) upward motion and small adiabatic cooling; (3) apparent heat source in the lowest layer. Sometimes such a shallow system seemed to develop into a strong cyclone. This was attributed to development of a synoptic-scale disturbance rather than to self-development of a mediumscale low.