A Coupled Experiment with LICOM2 as the Ocean Component of CESM1

In the present study, the LASG/IAP Climate system Ocean Model version 2 (LICOM2) was implemented to replace the original ocean component in the Community Earth System Model version 1.0.4 (CESM1) to form a new coupled model referred to as CESM1+LICOM2. The simulation results from a 300-yr preindustrial experiment by using this model were evaluated against both observations and the Flexible Global Ocean-Atmosphere-Land System Model with grid-atmospheric model version 2 (FGOALS-g2). It was found that CESM1+LICOM2 simulates well the mean features of the ocean, sea ice, and atmosphere, relative to models used in the Coupled Model Intercomparison Experiment (CMIP5), when compared with observations. The spatial distribution of SST bias in CESM1+LICOM2 is similar to that in the Community Climate System Model version 4 (CCSM4). The simulated climate variabilities, such as ENSO and Pacific decadal oscillation, are also reasonably simulated when compared with observations. The successful implementation of LICOM2 in the CESM1 framework greatly enhances the capability of LICOM2 in conducting high-resolution simulations and model tuning. Compared with FGOALS-g2, the simulations of both SST and Atlantic meridional overturning circulation are significantly improved in CESM1+LICOM2. The former can be mainly attributed to the atmospheric model, and the latter to the improvement in the parameterization of diapycnal mixing. The study provides a base to further improve the present version of LICOM and its functionalities in the coupled model FGOALS at both low and high resolutions.