A study of a mesoscale solitary wave in the atmosphere originating near a region of deep convection

Abstract

After the wave formed, it propagated in the direction of the mid- and upper-level tropospheric flow and expanded as an arc with the centre located near the region of convective activity. The wave travelled more than 1000 kilometers with a mean speed of 55 m s-1. Surface pressure traces showed an obvious V-shaped pressure drop of 3 to 6 mb over much of the wave path. The wave persisted for about 9 hours with little change in character. Waves of depression or elevation are described by a nondimensional number M Nz1/√g'H which is related to the depth and strength of the inversion, the stratification above the inversion, and the position of the heat source. The effects of nonlinearity and dispersion are determined to be the same order of magnitude. The theoretical description corresponding to the lowest eigenvalue mode describes the basic character of the disturbance as a wave of depression with a preferred propagation in the direction of the basic flow. Both characteristics are verified by observation. The phase speed calculated by the theory compare favourably with the observed values. -from Authors