A Comparison of Synoptic-Scale Vertical Motions Computed by the Kinematic Method and Two Forms of the Omega Equation

Abstract

A comparison is made between the kinematic method, the quasi-geostrophic omega equation and the general balance model omega equation during the growth of an intense extratropical cyclone from 0000 GMT 12 April to 1200 GMT 13 April 1964. Qualitative comparisons between vertical motions and synoptic features fail to establish the superiority of any of the methods. However, a simple scoring procedure devised to quantify the pattern comparisons and correlation coefficients calculated between vertical motions and precipitation amounts indicate that for this case the kinematic method is better than both forms of the omega equation. In addition, these tests yield the surprising result that the quasi-geostrophic omega equation is somewhat better than the general balance equation.