ENSO Diversity and the Simulation of Its Teleconnections to Winter Precipitation Extremes Over the US in High Resolution Earth System Models

Accounting for the diversity in El Nino Southern Oscillation (ENSO)'s spatial pattern, with the novel ENSO longitudinal index (ELI), we evaluate the simulation of its teleconnections to US winter precipitation extremes by seven global high-resolution (HR) Earth System Models (ESM). Six (four) HR ESMs simulate the observed increase in precipitation extremes over Southwest US (Southeast US) during ELI-defined El Nino events better than their low-resolution counterparts, which are low-biased. The stronger ENSO-dependence over the Southwest US and Southeast US in those models is associated with an improved simulation of moisture flux into the regions and/or storm track activity there. HR ESMs, however, generally overestimate the increase in precipitation extremes over the Pacific-Northwest during La Nina events. Model bias there is associated with bias in moisture transport into the region during La Nina events, which is amplified by the enhanced vertical mass fluxes in HR.