Study on Evolution Mechanisms and Energy Features of Northeast Cold Vortex with Heavy Rainfall Events
On the basis of NCEP CFS reanalysis data with a resolution of 0.5°×0.5°, conventional surface observation and FY2E satellite data from the China Meteorological Administration, detailed investigation was conducted to one northeast cold vortex (NECV) that caused several heavy rainfall events. The results indicate that the developing stage of the NECV is the most active period for convective activities and precipitation. Minimum TBB during the lifetime of the vortex is below -60℃, and maximum precipitation is 124 mm. The South China Sea, the Yellow Sea and the Japan Sea are main moisture sources for the heavy rainfall events associated with the NECV. The NECV is a kind of deeplydeveloped baroclinic vortex system with its strong baroclinicity and kinetic energy zones mainly located at the peripheral regions around the vortex. Cold regions associated with the vortex mainly appear in midupper troposphere and lower troposphere. Vorticity budget indicates that the vertical advection of vorticity that is closely related to convective activities dominate the formation of the NECV; the vertical advection of vorticity and the convergence effects are the most favorable factors to the rapid development of the vortex; and the divergence effects dominate the dissipation of the NECV. Kinetic energy budget indicates that the kinetic energy production by the rotational wind is the most favorable factor to the vortex during the formation stage; and during the maintaining stage, transport of kinetic energy by the rotational wind is the dominant factor to the sustainment of kinetic energy associated with the NECV.