STEPWISE DISCRIMINATION ANALYSIS OF POTENTIAL AREAS FOR RAIN ENHANCEMENT IN STRATIFORM CLOUDS IN NORTH CHINA

By means of the data of the 701 windfinding radar at Stations 07:00 and 19:00 of Changchun Meteorological Office and the 713 digital radar from Meteorological Bureau of Jilin Province in the past nine years, the potential areas of rain enhancement are classified into two categories: Class I (larger) and Class II (smaller), according to the data from cross-cloud observation. Two groups of discrimination functions S1, S2, are given, which include four meteorological factors obtained by using stepwise discrimination analysis method: 500 hPa south wind component, height of echo top, (negative temperature layer echo depth)/ (positive temperature layer echo depth) and (height of 0oC layer)/(height of echo top). Then, by using Microsoft VB6.0, Jinlin Province is divided into nine seeding operation areas according to radar echo parameters and 500 hPa wind from the near-time radiosonde observation; the automatic decoding and the rain enhancement potential calculation and automatic display for pre-seeding and stratifrom clouds are conducted.