The Experimental Research Of The Effect Of The Assimilation Of Cloud-derived Wind In MM5 Adjoint Assimilation System's Correction To The Model Terrain Field

In this paper, the MM5 adjoint-model that is based on variational method with adjoint codes technique as the core is introduced, on the basis of which, conventional observation data and unconventional observation data is applied into this Assimilation System for the purpose of assimilation research. First, choosing the conventional data of the heavy rain case that occurred in the Yangtze river drainage basin on July 29th, 1998 and putting it into the Assimilation System to study the assimilation effect. The result shows that the MM5 Adjoint-model Assimilation System can effectively assimilate the conventional data and adjust the initial field. The forecasting of meteorological element fields and precipitation is improved by use of the adjusted initial field. Second, the experiments of modifying the terrain parameter by means of the MM5 Adjoint-model Assimilation System are carried out. In these experiments, conventional observation data and unconventional data (cloud-derived wind) is used. By comparison of the results of different experiments, it is known that the using of unconventional data in the adjoint assimilation model will correct the topography more effectively than using only the conventional observation data. The forecasting conducted on the basis of this terrain field can be improved by contrast to the results using only conventional data.