Abstract | This poster summarizes key attributes of the global sea ice solution in the E3SMv2 North American Regionally Refined Model (NARRM) relative to the standard coupled model. We compare 500-year preindustrial simulations of the two models as well as historical ensembles to understand the impact of 14km marine regional refinement over the entire Arctic Ocean and North American coastal regions. This is coupled to 25km atmospheric refinement extending to abyssal areas off North American coasts. The refinement is relative compared to the standard model with 30-60km and 100km respective standard resolution ocean and atmosphere meshes. For the pre-industrial control, Arctic regional refinement results in an average 5000 to 6400 km3 greater simulated ice volume in the Northern Hemisphere than at standard resolution, a 16% (winter) to 57% (summer) increase over the 500-year preindustrial controls at 99% compatibility. There is only a small associated improvement in Arctic summer sea ice extent, and virtually no change in southern hemisphere ice cover relative to standard resolution. For Using daily sea ice means from E3SM, our analysis indicates there is a marked increase in northern hemisphere sea ice volume with regional refinement, but little improvement in Arctic and Antarctic winter sea ice extent. For the industrial period, we intercompare inter-compare 5-member ensembles against the latest version of the NOAA Climate Data Record of ice concentration to provide an integrated ice edge error. This indicates and the Pathfinder dataset of sea ice drift. These comparisons indicate there is little improvement within 2𝝈 of in E3SM as compared to the observed winter ice edge even with Atlantic regional refinement, and that the NARRM model configuration does not resolve a chronic ice-edge bias in the model. Both models successfully reproduce climatological circulation features seen in the Polar Pathfinder approximation of sea ice drift from 1980 to 2014, with an increase in sea ice kinetic energy associated with eddying activity and coastal currents where regional refinement is most pronounced. The end-of-melt-season trend in northern hemisphere extent, as measured on the equinox, is similar and largely unbiased as compared to observations, while the southern hemisphere is biased and the trend has the wrong sign in E3SM. Both models produce markedly different circulation patterns in the Arctic relative to the Pathfinder drift dataset, however results from that dataset draw into question its veracity, and we are investigating this further by comparing with independent buoy drift datasets. |
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