In this study, an advanced land surface process model SiBUC(Simple Biosphere including Urban Canopy) is coupled into a mesoscale numerical atmospheric model ARPS(Advanced Regional Prediction System). SiBUC uses mosaic approach to incorporate all kind of land-use into LSS. Precise description of urban area and cropland including paddy field are important aspects of SiBUC.

During the intensified field campaign of the Lake Biwa Project 2001, well developed local circulation was observed in the Lake Biwa Basin in Japan on typical summer sunny day (14th August 2001). This case was simulated by both original ARPS (with simple land surface model) and ARPS-SiBUC. Through the comparison of the simulated atmospheric fields with surface observation data and radiosonde data, it turns out that mosaic approach and urban canopy model of SiBUC can improve the development of local circulation and accuracy of near surface air temperature.