A MESOSCALE MODEL INCLUDING POSITIVE WATER TRANSPORT ALGORITHMS AND NUMERICAL EXPERIMENT

It is a very important and difficult problem for prediction heavy rain. The moisture transport plays important role in modeling the mesoscale weather process. Based on mesoscale model MM4, by cooperating with some more accurate water transport schemes, a mesoscale numerical weather prediction system NMM is developed. These schemes include: (1) B-grid Center Conservative Scheme which is used in MM4; (2) Bott (2-order) Scheme;(3) Bott (4-order) Scheme; (4) Upstream Scheme; (5) Prather Scheme. Bott Scheme and Prather Scheme Both Schemes are positive and produces a lit tle numerical diffusion and computation dispersion. Numerical experimete of move heavy rain process under the model water transport algorithm's options of B-grid Center Scheme, Upstream scheme and Prather Scheme shown the high accurate water transport algorithms, just like Prather scheme improving the precipitation prediction of the mesoscale model and giving more accur ate results of the short range precipitation system.