Properties and diagnose of horizontal kinetic energy gradientin multilevel model

Based on multilevel primary equations of motion, the relations between the horizontal kinetic energy gradient at each level and the corresponding geostrophic deviation of weather systems over different scales are obtained. The diagnostic analysis on horizontal kinetic energy gradient of the rainstorm on July 22, 2010 in Nanjing are carried out. The main results are as follows. For atmospheric systems of synoptic scale and meso-α scale, the value of horizontal kinetic energy gradient is approximately proportional to the value of geostrophic deviation at each level. The proportional coefficient for the system of synoptic scale is the geostrophic coefficient, and independent of the system. While the proportional coefficient for a smaller scale atmospheric system is closely related to the system. For atmospheric system of meso-β scale, the value of horizontal kinetic energy gradient is less than the sum of two terms at each level. The first term is proportional to the value of geostrophic deviation and the second one is the value of the time derivative of geostrophic deviation. In the high value area of horizontal kinetic energy gradient, the nonequilibrium behavior and outbreak behavior of atmospheric motion are strong. The values of kinetic energy gradient at each level over precipitation areas and squall line are greater. The analysis of the magnitude of kinetic energy gradient makes it possible to diagnose and analyze atmosphere systems of various scales in wind field terms, which is important to the diagnostic analysis of meso scale systems.