Limited Area Of ​​three-dimensional Climate Model Nested Method A Preliminary Study

As well-known, the regional model nested with the global model is a new option for climate modeling at present, although a number of problems still remain to be solved, such as the lateral boundary errors which are considered as one of the main errors existing in the regional model, in particular, the error accumulation associated with long time integration.In this article, a new method, namely, the Three Dimensions Nesting method is introduced to reduce the accumulated lateral boundary errors in regional model. The preface elaborated the necessity, and the rationale supporting this method. A series of schemes of Three Dimensions Nesting have been tested by means of the Regional Climate Model (REG-CM2) from which the optimal scheme has been chosen after comparing all the numerical simulation results with the observed fields. Then the comparison studies between Three Dimensions Nesting and the traditional scheme (i.e. the Horizontal Lateral Boundary Nesting) were carried out. Comprehensive analysis shows that Three Dimensions Nesting runs steadily and reduces the accumulation of lateral boundary errors significantly, especially in model long-time integration. The prediction of precipitation is better than the traditional scheme, in particular, for the intensified rain. The simulations of other fields are also improved in different extent. The advantages of Three Dimensions Nesting method became even obvious as the model time integration goes on for longer period. The results show that the proposed new method for nesting lateral boundary is rational; the technique has been successfully adapted to the REG-CM2 model, it can also be applied in other models and with different vertical coordination. The study also provides a solid foundation for further developing three dimensions nesting technique in the future.