Development of Coupled Modeling System for Regional Water Cycle and Material Transport in the Atmospheric, Terrestrial, and Oceanic Environment

Abstract

Numerical simulations are the effective approach to investigate the complex mechanism in environmental pheno- mena and many numerical models have been developed for specific applications over wide range of field. Recently, much effort has been made to develop numerical models that can deal with the multi-physics problems in the com- plex environmental system. Most of these models are constructed by coupling existing models developed separately for their specific field of studies and called as coupled models. A general-purpose model coupling program of Japan Atomic Energy Agency (JAEA-Coupler) has been developed to construct local to regional scale coupled models for environmental studies. In these coupled models, calculations of component models are carried out by different processors of parallel computers in the same manner as their origi- nal stand-alone calculations and the coupler controls these processes and handles data exchanges among component models using Message Passing Interface (MPI). Data exchanges are only conducted between the coupler and each component model and the coupler handles the data distribution to target models with interfacing spatial, temporal, and physical discrepancies among component models. By using JAEA-Coupler, integrated coupled models to simulate regional water cycle and material transport have been constructed. The coupled model for regional water cycle consists of the non-hydrostatic atmospheric dynamic model of PSU/NCAR (MM5), detailed multi-layer land surface model (SOLVEG) and three-dimensional hydrology model (RIVERS) developed by JAEA, the third-generation ocean wind-wave model of NOAA (WW3), and the Prin- ceton Ocean Model (POM). For the material transport, Lagrangian particle dispersion models for the atmosphere and ocean (GEARN and SEA-GEARN, respectively) developed by JAEA are incorporated into the water cycle coupled model, where RIVERS includes the function to calculate material transport. Test calculations were carried out to si- mulate water movement after heavy rainfall and dissolved material transport after a hypothetical release to the atmosphere. These results show the validity of the coupled models in appropriate data exchanges for complex inte- ractions among component models and reasonable reproduction of the target phenomena.