A document by Hannah Glover. Click on the document to view its contents.

The retreat of Arctic sea ice is enabling increased ocean surface wave activity at the sea ice edge, yet the physical processes governing interactions between waves and sea ice are not fully understood. Here, we use a collection of in situ observations of waves in ice to evaluate a recent global climate model experiment that includes coupled interactions between ocean waves and the sea ice floe size distribution. Observations come from subsurface moorings and free-drifting buoys spanning 2012-2019 in the Beaufort Sea, and we group the data based on distance inside the ice edge for comparison with model results. Locally generated wind waves are relatively prevalent in observations beyond 100 km inside the ice but are absent in the model. Low-frequency swell, however, is present in the model, while subsurface moorings located more than 100 km inside the ice do not report any swell with significant wave height exceeding the instruments' detection limits. These results motivate further model development and future observing campaigns, suggesting that local wave generation inside the ice edge may play a significant role for floe fracture while demonstrating a need for more robust constraints on wave attenuation by sea ice.

The thermodynamic growth of sea ice is a critical factor in the mass balance of Arctic sea ice, which has important implications for Arctic communities and the global climate. However, the magnitude by which snow atop Arctic sea ice limits thermodynamic ice growth is still not fully understood. Prior work has shown that the wind-driven snow redistribution could significantly modify the heat conduction through the snow cover and hence the rate of thermodynamic ice growth. However, the effects of snow redistribution on sea ice growth have not been quantified and are not well represented in climate models. We use observations from the MOSAiC expedition to show how different facets of snow redistribution can enhance or reduce heat conduction through the snow cover for the same mean snow thickness. The net effect depends on ice topography and environmental conditions. For example, snow redistribution onto young ice in April at MOSAiC reduced heat conduction by approximately 5-15%. We quantify the impact winter and springtime snow redistribution events on the heat conduction on deformed, level, and young ice. We explore the implications of these snow redistribution processes in the Community Earth System Model and discuss priorities for improving climate models.