Will Increasing Climate Model Resolution Be Beneficial for ENSO Simulation?

Abstract

Increasing climate model resolution offers multifaceted benefits, such as improving modeled tropical cyclones. However, the extent to which it benefits El Niño-Southern Oscillation (ENSO) simulation remains unknown. Here, comprehensive information on the sensitivity of ENSO performance to various resolutions is provided, based on a multi-model and multi-resolution ensemble of global coupled models. Overall, the reduced model biases of the equatorial sea surface temperature (SST) and precipitation mean state in higher-resolution models may be attributed to increased oceanic resolution, and thus, better resolved eddy-driven heat transport. ENSO spatial patterns were reproduced clearer in the eddy-present models, likely due to the improved mean state and associated surface thermodynamic feedback. However, increasing atmospheric resolution alone deteriorates ENSO asymmetry, which may be due to the degradation of nonlinear atmospheric feedback. It remains challenging to alleviate the SST−shortwave-flux feedback bias, which is a major source of too-weak net heat flux feedback, irrespective of model resolution.