Toward quantifying the impact of atmospheric forcing on Arctic sea ice variability using the NPS 1/12 degree pan-Arctic coupled ice-ocean model

Abstract

The rapid Arctic sea ice decline since the 1970s has propelled the United States into a state of urgency for updating its defense plan as Arctic and non-Arctic nations alike are taking an interest in the newfound natural resources of an ice-declining Arctic. In line with the National Security Presidential Directive-66, we quantify the amount of anomalous sea ice variability (aSIV) that anomalous atmospheric forcing parameters explain using partial covariance analysis. A one-system approach where the NPS Model sea ice parameters are the direct output of the atmospheric forcing parameters input is employed. Atmospheric forcing fields of 2-m temperature, downward shortwave and longwave fluxes, 10-m zonal and meridional winds and stresses, are from the European Centre for Medium-Range Weather Forecasts Reanalysis-15 and Operational Products. Locations of interest are the Central Arctic seas, and locations along the Northwest Passage (NWP) and the Northern Sea Route (NSR). Results show that the atmospheric parameter having the largest influence on aSIV is anomalous surface air temperature. This occurs during the cooling months and averages 4-39% of aSAT contribution to aSIV in the Central Arctic, 9-16% along the NWP, and 11-25% along the NSR. Results also suggest that atmospheric forcing alone does not explain all of aSIV.