Water cycle and microphysical processes associated with a mesoscale convective vortex system in the Dabie Mountain area

Abstract

The water vapor budget and the cloud microphysical processes associated with a heavy rainfall system in the Dabie Mountain area in June 2008 were analyzed using mesoscale reanalysis data (grid resolution 0.03° × 0.03°, 22 vertical layers, 1-h intervals), generated by amalgamating the local analysis and prediction system (LAPS). The contribution of each term in the water vapor budget formula to precipitation was evaluated. The characteristics of water vapor budget and water substances in various phase states were evaluated and their differences in heavy and weak rainfall areas were compared. The precipitation calculated from the total water vapor budget accounted for 77% of actual precipitation; surface evaporation is another important source of water vapor. Water vapor within the domain of interest mainly came from the lower level along the southern boundary and the lower-middle level along the western boundary. This altitude difference for water vapor flux was caused by different weather systems. The decrease of local water vapor in the middle-lower layer in the troposphere during the system development stage also contributed to precipitation. The strength and the layer thickness of water vapor convergence and the content of various water substances in the heavy rainfall areas were obviously larger than in the weak rainfall areas. The peak values of lower-level water vapor convergence, local water vapor income, and the concentration of cloud ice all preceded the heaviest surface rainfall by a few hours.