Coupling of Integrated Land Simulator to MIROC6's Atmosphere and Ocean Models

Accurate simulation of terrestrial energy and hydrological cycles is crucial for various purposes such as flood and drought forecasting and climate projections. To achieve this goal, we have developed an Integrated Land Simulator (ILS; Nitta et al., 2020) that allows the coupling of various land component models with minimum modifications. ILS is designed to 1) make a land part independent from atmospheric models to use appropriate grid coordinates and resolutions, 2) validate land-only experiments using near real-time observation-based meteorological data during development, and 3) use an accurate and up-to-date land model in climate models. In this study, we coupled ILS with MIROC6's atmosphere and ocean models using the same general purpose coupler in ILS. ILS used 0.5-degree catchment-shaped grids, which differs from the AGCM and the OGCM. We conducted historical experiments following the CMIP6 protocol. Surface meteorological field and fluxes were exchanged between the AGCM and the ILS every 12 minutes. We verified that the 30-year simulations ran without any problems, and the water balance for each model was closed within the acceptable level. Also, we evaluated the computational efficiency and showed that ILS was fast enough compared to the AGCM and OGCM. In the presentation, we will also show how coupling frequency between land and atmosphere affects surface flux and climate and discuss current issues.