Nonlinear instability of baroclinic atmosphere with reference to planetary scale disturbances

I. A. Pisnichenko (1)

1 CPTEC - Center for Weather Forecasting and Climate Studies [São Paulo]

In this paper we investigate the stability of zonal flow in a baroclinic atmosphere with respect to finite-amplitude planetary-scale disturbances by applying Arnold's method. Specifically, we examine the sign of the second variation of a conserved functional for the case of a polytropic atmosphere (i.e. one with a linear lapse rate) and with a linear profile of zonal wind. Sufficient stability conditions for an infinite atmosphere (i.e. with a temperature lapse rate equal to zero) are satisfied only for an atmosphere in solid body rotation. For a polytropic atmosphere of finite extent (a lapse rate is not equal zero) the sufficient conditions of stability can be satisfied if a lid is placed below min (Z_max, polytropic atmospheric height). The dependence of height Z_max on values of the vertical gradient of the zonal wind and the zonal temperature distribution is calculated.

Domaines: Cosmologie et astrophysique extra-galactique [astro-ph.CO]; Astrophysique [astro-ph]; Sciences de la Terre

I. A. Pisnichenko. Nonlinear instability of baroclinic atmosphere with reference to planetary scale disturbances. Nonlinear Processes in Geophysics, 2004, 11 (3), pp.363-370. ⟨hal-00302348⟩