Atmospheric river representation in the Energy Exascale Earth System Model (E3SM) version 1.0

Abstract. The Energy Exascale Earth System Model (E3SM) project is an ongoing, state-of-the-science system modeling, simulation, and prediction developed by the US Department of (DOE). With emphasis on supporting DOE's energy mission, understanding quantifying how well model simulates water cycle processes particular importance. Here, we evaluate E3SM version 1.0 (v1.0) for its ability to represent atmospheric rivers (ARs), which play significant roles in vapor transport precipitation. characteristics precipitation associated with global ARs at standard resolution (1∘ × 1∘) are compared Modern-Era Retrospective analysis Research Applications, 2 (MERRA2). Global patterns AR frequencies show high degrees correlation (≥0.97) MERRA2 low mean absolute errors (MAEs; <1 %) annually, seasonally, across different ensemble members. However, some large-scale condition biases exist, leading – most double intertropical convergence zone (ITCZ), a stronger and/or equatorward-shifted subtropical jet during boreal austral winters, enhanced Northern Hemisphere westerlies summer. By comparing atmosphere-only fully coupled simulations, attribute sources component or coupling response. Using relationships revealed Dong et al. (2021), provide evidence showing North Pacific winter summer, E3SM's ITCZ related weaker Atlantic meridional overturning circulation (AMOC), respectively, found simulations.