Application of a Coupled Regional-Scale Hydrological-Atmospheric Model to Japan for Climate Change Study

Abstract

This paper presents the improved performance of a regional climate model for the Japan region when a fully coupled boundary layer model and an areally averaged land–surface flow model are employed. It also describes results from the application of the regional climate model to the region for climate-change prediction. An integrated regional-scale hydrological-atmospheric model (IRSHAM) was developed for the Japan region that consisted of a 60-km resolution large-domain model nesting a 20-km resolution small-domain model. The small-domain model was equipped with two-way interaction between the areally averaged land–surface parameterization and the first layer of the atmospheric model. A historical period was then simulated by IRSHAM for local precipitation and other hydrological processes. Simulation results showed a significant improvement in the monsoon-affected regional distribution of monthly precipitation in the Japan region. The simulation results correlated with their counterparts observed at the Tsukuba ground station, showing that IRSHAM performed well in predicting daily meteorological changes. IRSHAM performed another run to simulate local-scale effects of the climate change caused by a doubling of the