Analysis on "96. 8" Heavy Rainstorm Process in Handan

[ ObjEtive] The research aimed to analyze ＂96.8＂ heavy rainstorm process causing flood disaster in Handan. [ Method] Based on ac- tual situation data, satellite cloud data and NCEP reanalysis data in the first dekad of August in 1996, ＂96.8＂ heavy rainstorm process causing flood disaster in Handan was analyzed to understand occurrence reason of the flood disaster. [ Result] Two meso-scale convective cloud clusters which developed and went north in turn caused ＂96.8＂ heavy rainstorm in Handan. Typhoon and inverted trough were main weather systems induced flood disaster in Handan. In going north process of the low-level jet, due to blocking of the subtropical high, water vapor and energy accumulated in Handan, providing material basis for formation of the heavy rainstorm. Development and eastward movement of the short-wave trough at middle lati- tude and continuous invasion of the reflux weak cold air at the low layer were direct reason for triggering generation and development of the convec- tive cloud cluster, and further causing continuous rainstorm. Wet layer over the rainstorm zone was deep and thick. Meridional distribution of the wet zone was wider than latitudinal distribution. South China Sea and Bay of Bengal were water vapor sources for the rainstorm zone. In the whole rain- storm period, it was convergence at low layer and divergence at high layer in the rainstorm zone. It was positive vorticity at low layer and negative vorticity at high layer. Precipitation intensity changed as convergence and divergence. Rainstorm zone had strong ascending motion. As strengthe- ning and uplifting of the ascending motion strong center, strong precipitation also strengthened. Rainstorm center was near the biggest vertical ve- locity center. Strong precipitation changed as vertical ascending motion. [ Conclmion] The research provided scientific basis for disaster prevention and reduction and decision-making service.