Furthermore, the conventional observations are done in the MM5 model system, and a four-dimensional variational data assimilation test is made based on observed data.

The key problem of four-dimensional variational data assimilation method, which solves the constraining numerical predict equations through accompanied model, is how to establish an accompanied model.

The four-dimensional data assimilation is to integrate the current and past data into a forecast model equation for providing time continuity and dynamic coupling.