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Publication Date
29 December 2021

Simulation of ENSO teleconnections to precipitation extremes over the US in the high resolution version of E3SM

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<p>We evaluate the simulated teleconnection of El Ni&ntilde;o Southern Oscillation (ENSO) to winter season precipitation extremes over the United States in a long (98 years) 1950-control high resolution version (HR, 25 km nominal atmosphere model horizontal resolution) of US Department of Energy&#39;s (DOE) Energy Exascale Earth System Model version 1 (E3SMv1). Model bias and spatial pattern of ENSO teleconnections to mean and extreme precipitation in HR overall are similar to the low-resolution model&#39;s (LR, 110 km) historical simulation (4-member ensemble, 1925-1959). However, over the Southeast US (SE-US), HR produces stronger El Ni&ntilde;o associated extremes, reducing upon LR&#39;s model bias. Both LR and HR produce weaker than observed increase in storm track activity during El Ni&ntilde;o events there. But, HR improves the ENSO associated variability of moisture transport over SE-US. During El Ni&ntilde;o, stronger vertical velocities in HR produce stronger large-scale precipitation causing larger latent heating of the troposphere that pulls in more moisture from the Gulf of Mexico into the SE-US. This positive feedback also contributes to the stronger mean and extreme precipitation response in HR. Over the Pacific Northwest, LR&#39;s bias of stronger than observed La Ni&ntilde;a associated extremes is amplified in HR. Both models simulate stronger than observed moisture transport from the Pacific Ocean into the region during La Ni&ntilde;a years. The amplified HR bias there is due to stronger orographically driven vertical updrafts that create stronger large scale precipitation, despite weaker La Ni&ntilde;a induced storm track activity.</p>

Mahajan, Salil, Qi Tang, Noel D. Keen, Jean-Christophe Golaz, and Luke P. Van Roekel. 2021. “Simulation Of Enso Teleconnections To Precipitation Extremes Over The Us In The High Resolution Version Of E3Sm”. Journal Of Climate, 1-62. doi:10.1175/jcli-d-20-1011.1.
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