| 线性和非线性正压不稳定 |
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| 引用本文： | 陆维松.线性和非线性正压不稳定[J].气象学报,1987,45(3):274-281. |
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| 作者姓名： | 陆维松 |
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| 作者单位： | 南京气象学院 |
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| 摘 要： | 本文从无摩擦的、无辐散的非线性正压涡度方程出发,利用行波解,在相平面上对方程的平衡点分别导得线性和非线性正压不稳定判据,与传统的不稳定判据作了比较分析。还求得了线性和非线性不稳定波的解析解,计算结果表明,若初始时刻两者波幅相等,则以后非线性不稳定波幅的增长值总小于线性不稳定波幅的增长值。非线性效应有使线性不稳定指数型增长减缓的作用。不稳定使得振幅比初始时刻增大一倍所需要的时间,对于线性不稳定大约是6h,对于非线性不稳定大约是18h,后者与实际大气中的观测事实是一致的。
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| 收稿时间： | 1986/5/24 0:00:00 |
| 修稿时间： | 1986/10/4 0:00:00 |
LINEAR AND NONLINEAR BAROTROPIC INSTABILITY |
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| Lu Weisong.LINEAR AND NONLINEAR BAROTROPIC INSTABILITY[J].Acta Meteorologica Sinica,1987,45(3):274-281. |
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| Authors: | Lu Weisong |
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| Institution: | Nanjing Institute of Meteorology |
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| Abstract: | Starting from a non-frictional and non-divergent nonlinear barotropic vorticity equation, using solution of the travelling waves, the linear and nonlinear bartropic instability criterions are gained respectively at an equilibrium point of the equation on a phase plane, these criterions are compared and analysed with the traditional instability criterions. The linear and nonlinear analysis solutions are also found. The computational results show that if amplitudes both of these instabilities are equal at initial time, the amplitude increments of the nonlinear barotropic instability are always less than these of the linear barotropic instability, the nonlinear effects can slow the exponential growing of linear instability, necessary time that two kinds of instabilities cause that amplitudes go up once as compar with initial ones for, is about 6 hours for linear instability, and is 18 hours for nonlinear instability, the latter is identical with the observational facts in the real atmosphere. |
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