中层大气重力波的一种激发机制及其数值模拟 I. 非地转不稳定和波结构

本文用FGGE资料分析了1979年2月—3月一次爆发性增温期间平流层环流的不稳定性，从而说明在平流层爆发性增温期间伴随产生大振幅重力波活动的原因。分析结果表明:在平流层爆发性增温期间，大气中存在着很强的并且是系统性的非地转运动，从而产生非地转不稳定。强烈的地转偏差的存在激发出大振幅重力波。我们还应用一个线性化扰动方程求得了非地转不稳定判据；并且用数值方法分析了这次爆发性增温期间基流的特征谱点和不稳定波结构。计算结果表明基流满足非地转不稳定条件，具有快波性质的波动出现了不稳定。

A Possible Mechanism for Exciting Gravity Waves in Middle Atmosphere and Its Numerical Simulation. Part I: Ageostrophic Instability and Wave Structure

In this paper, the FGGE data from February 12 to March 4, 1979 are used to analyse t e instability of stratospheric circulation during the sudden warming. We attempt to show ho'\ thegravity waves with large amplitude are excited during the sudden warming. The analyses sa 4gestthat during the sudden warming there are very strong and systematic ageostrophic movel lentswhich cause gravity waves with large amplitudes. A set of linearized disturbance equati(tls isemployed to obtain the instability criteria. A difference method is used to calculal theeigenvalue and eigenfunction of the mean flow during the sudden warming. The results shod thatthe mean flow is ageostrophically unstable. Also the structure of instable waves is investiga:d indetail.