On simulation improvement of the Noah_LSM by coupling with a hydrological model using a double-excess runoff production scheme in the GRAPES_Meso model

Abstract

Land surface models play an important role in simulating mass, energy and momentum exchanges between the atmosphere and land surface in numerical weather prediction systems. The Noah land surface model (Noah_LSM) is adapted to describe the water and energy balance in the GRAPES_Meso model (V4.0). However, the Noah_LSM does not distinguish the infiltration-excess runoff and the saturation-excess runoff effects and does not simulate runoff routing, making its applicability limited in China. In this work, the Noah_LSM was improved by incorporating double-excess runoff production and routing schemes. The double-excess runoff production scheme is based on the depletion of water storage coupling with the Holtan method. The Muskingum model is used for routing. To evaluate the performance of the improved model, numerical simulations were carried out using the old and improved models to investigate the feedback of changes in the land surface hydrological model to numerical simulations for meteorology. The results demonstrate that the improved land surface hydrological model affects numerical simulations for meteorology in terms of the soil temperature, soil moisture, air temperature and wind speed as well as predicting rainfall events better in terms of the rainfall regime.