Large-Scale Energy Transport by Freezing Rain and Snowstorms in Southern China in January 2008

Local energy generation and conversion in freezing rain and snowstorms over southern China between 26 and 28 January 2008 were investigated using the NCEP-DOE Reanalysis 2 data. In the subtropical jet, the mean kinetic energy (K_m) converts energy into interaction kinetic energy (K_i) flow, and then transient-eddy kinetic energy (K_e) is gained from the K_i flow. The K_i flow has the same orientation as the subtropical jet. The term for baroclinic conversion between K_e and A_e (ω_eα_e) and the geopotential height advection terms were about one order of magnitude lower than the terms for the conversions between K_m and K_i (C(K_m, K_i)) and between K_i and K_e (C(K_i, K_e)). The transient-eddy available potential energy (A_e) mainly obtained energy indirectly from the mean available potential energy (A_m) over central-southern China because of the interaction available potential energy (A_i) flow. At 1200 UTC on 26 January 2008, there were two sources of A_i flow, one over the Tibetan Plateau and the other over northeastern China. The two sources shifted eastward over time so the energy conversions also shifted eastward. The A_i flows had two orientations, one being the orientation opposite that of the subtropical jet and the other in the same direction as the subtropical jet.