Numerical Analysis of Wind and its Application to the Numerical Weather Forecasting (Part 1)

Abstract

In section 3, we compute divergence and relative vorticity for each level at about 100-mb intervals from 950 to 300-mb by use of the observed winds. The results show that the patterns of divergence and relative vorticity are fairly smooth beyond our expectation. In the lower atmosphere, the maximum divergence is found slightly ahead of the cyclone in the contour field. In a broad sense, the magnitude of divergence is largest near the ground surface and weakest near 600-mb level.In section 4, we tried to perform the numerical forecasting at the minimum divergent level, namely 600-mb level. The non-barotropic forecasting, in which all terms in the vorticity equation are taken into consideration, is concluded to be fairly superior to the barotropic one, in which the stream function is used. This is accepted by the fact that, even in the minimum divergent level, the divergence term in the vorticity equation is of the same order of magnitude as the horizontal advection term.