Diagnostic Analyses of the Modified Convective Vorticity Vector in Non-uniformly Saturated Moist Flow

Abstract

Because the real atmosphere is non-uniformly saturated, the generalized potential temperature is introduced. The convective vorticity vector, which can depict the occurrence and development of mesoscale deep convective systems, is modified and re-derived in a nonuniformly saturated moist atmosphere (C^*). Then, a case study is performed for a frontal rainfall event which occurred near the middle and lower reaches of the Yangtze River in China. The diagnostic results of C^* show that, in the lower troposphere, the vertical component of C^* (C^*_z ) can diagnose developments and movements of precipitation and convection better than those of C_m (C_mz, in saturated moist flow) and C (C_z, in dry flow). C^*_z is a good predictor for precipitation analyses as well.

Key Words:

• non-uniform saturation
• generalized potential temperature
• modified
• convective vorticity vector