Investigating the linkage between simulated precipitation climatology and ENSO-related precipitation anomaly based on multi-model and perturbed parameter ensembles

Abstract

It remains a challenge for climate models to correctly capture the relationship between precipitation and ENSO. This study examines the linkage between the simulated precipitation climatology and ENSO-related precipitation anomaly during boreal winter based on the multi-model ensemble from the Atmospheric Model Intercomparison Project Phase 5 (AMIP5) and perturbed parameter ensemble (PPE) with the Beijing Climate Center (BCC) atmospheric model. The AMIP5 models have large biases in simulating the tropical precipitation anomaly during El Nino, such as the shifts of the Inter-Tropical Convergence Zone (ITCZ) and South Pacific Convergence Zone (SPCZ). The inter-model differences show that the precipitation change in response to sea surface temperature (SST) change increases with enhanced precipitation climatology. The ENSO-related precipitation anomaly can also be related to the spatial distribution of the mean-state precipitation. The simulated ITCZ/SPCZ displacements are significantly correlated with the spatial precipitation-SST relationship in the mean state. Models with stronger mean-state precipitation-SST relationship also produce stronger SPCZ/ITCZ displacements. The mean-state tropical precipitation also has strong impacts on the ENSO-related precipitation anomalies over East Asia. In the BCC PPE, the connection between the mean-state precipitation and ENSO-related precipitation anomaly is overall consistent with that in AMIP5. Parameters associated with the low-cloud and deep convection processes are the most influential ones for the precipitation simulations in BCC. Compared with the version in AMIP5, the new BCC model can better simulate the precipitation climatology and the relationship between ENSO and precipitation over southern China. These results have important implications for model development and model-based climate predictions.