Seasonal variation and latitudinal distribution of the instability of two-level quasi-geostrophic waves in horizontal shear

Chung-Muh Tang

doi:10.3402/tellusa.v25i3.9658

Seasonal variation and latitudinal distribution of the instability of two-level quasi-geostrophic waves in horizontal shear

Tellus

Volume 25 (1973): Issue 3

By: Chung-Muh Tang

Open Access

|Jan 1973

Abstract

The instability of a simplified, combined baroclinic-barotropic, two-level quasi-geostrophic model is investigated. The results are applied to the observed mean zonal wind, which varies with season and latitude, by approximating the sphericity of the earth by infinite tangent β-planes. Maximum instability is found to exist in winter at about 37° N, for zonal wave number 7, changing to zonal wave number 6 in higher middle latitudes and to lower zonal wave numbers in polar latitudes. The latitudinal and spectral bands of instability shrink gradually from winter through spring, reach a minimum in summer, and gradually widen in fall.

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