Diagnostic Analysis of Precipitating Convective Process in East China with Moist Baroclinic Vorticity Parameters

The moist baroclinic vorticity (MBV) and moist thermodynamic baroclinic vorticity (MTBV) contain the vorticity information perpendicular to the potential temperature gradient which is excluded by moist potential vorticity (MPV). The MBV represents horizontal advection of the moist specific volume by shear wind. The MTBV indicates the coupling of the vertical pressure gradient, convective instability, vertical wind shear, and horizontal gradient of moist specific volume. A strong precipitating convective process in East China on August 17, 2009, is studied with these physical variables in this paper. The results show that a close configuration of a high-level jet stream, mid-level shallow trough, and low-level shear line induces this event. The convective system in this process undergoes three development stages: the nonsquall cluster stage, squall line and nonsquall cluster coexistence stage, and the nonsquall cluster redevelopment stage. It is shown that the MPV, MBV, and MTBV can indicate the location and evolution of the precipitation inside the convective system effectively. However, the MBV and MTBV are more sensitive to the change of the precipitation intensity and thus more capable of indicating precipitation in this case.