Korea Institute of Ocean Science and Technology Earth System Model and Its Simulation Characteristics

We document the performance of a new earth system model developed at Korea Institute of Ocean Science and Technology, called the KIOST-ESM, based on a low-resolution (~ 200 km for the atmosphere, ~ 100 km for the ocean) version of the Geophysical Fluid Dynamics Laboratory Climate Model 2.5. The main changes made to the base model include adopting a unified convection scheme for cumulus convection and an ocean mixed layer parameterization considering Langmuir circulation, which improve the model fidelity significantly. In addition, the KIOST-ESM adopts a new soil respiration scheme in the dynamic vegetation process of its land component. The performance of the KIOST-ESM was assessed in pre-industrial and historical simulations that are made as part of its participation in the Coupled Model Intercomparison Project phase 6 (CMIP6). The response of the earth system to increasing greenhouse gas concentrations was analyzed in the ScenarioMIP simulations. An abrupt quadrupling of CO 2 experiment suggests that the equilibrium climate sensitivity of KIOST-ESM is 3.36 K—very close to the averaged one obtained from CMIP5 simulations. Although the KIOST-ESM showed a notable cold bias in the Northern Hemisphere and the double Inter-Tropical Convergence Zone bias, the KIOST-ESM outperforms the base model in simulating the mean sea surface temperature over the Southern Ocean and over the cold tongue in the tropical Pacific. The KIOST-ESM can also simulate the dominant tropical variability in intraseasonal (Madden–Julian Oscillation) and interannual (El Niño-Southern Oscillation) timescales more realistically.