高空輻散與劇烈天氣之關係

陳毓雷

　　The prediction of severe weather depends largely on the following four factors : high altitude divergence, low level moisture supply, instability and low level convergence ( related to LLJ), of which the first is of prior importance. Here the term “high altitude ” should be defined as 200~300mb level, and the divergence area can be determined gualitatively in terms of the jetstream core. Quantitative method is also introduced prorided wind field data is available and sufficiently accurate. Two typical cases in the U.S. and Taiwan are presented to illustrate the procedure of severe weather prediction using high altitude divergence as the main predictor.