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

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.