Numerical simulation study on the coupling of a regional climate model with a hydrological model

Abstract

This paper numerically simulated the climate situation of rainstorms and surface runoff in the Yangtze basin in 1998 in China. Results show that the regional climate model (RegCM2) can successfully simulate the location and strength of the subtropical high, the Tibetan upper-air high centre and surface thermal low, the cool and warm advection to the east and west side of the Tibetan plateau, and also the confluence of north and southwesterly air flow branches over east China. On the basis of the above simulation, the model was used further to simulate precipitation, for example, the range and location of more than 600 mm rainfall, the 300 mm closed isopluvial, and the 100-500 mm precipitation area of the storm in the south of China, by coupling the general variable infiltration capability (GVIC). The study on the impact of GVIC on the regional climate simulation indicates that the GVIC runoff scheme improved the modelling of moisture convergence, increased the moisture content in the atmosphere below 700 hPa, and enhanced precipitation in the Yangtze River basin. The experiment of coupling RegCM2 with the hydrological model shows that the trend of calculated drainage is consistent with that of the observations, especially for drainage rising and fluctuation processes in June and August, respectively, in spite of some differences between their magnitudes. The simulated drainage at Yichang and Hankou, using the coupling model, are generally consistent with the observations from June to August.