Preprints
https://doi.org/10.5194/tc-2021-67
https://doi.org/10.5194/tc-2021-67

  05 Mar 2021

05 Mar 2021

Review status: this preprint is currently under review for the journal TC.

Arctic sea ice sensitivity to lateral melting representation in a coupled climate model

Madison Smith1, Marika Holland2, and Bonnie Light1 Madison Smith et al.
  • 1Applied Physics Lab, University of Washington, Seattle, Washington, USA
  • 2National Center for Atmospheric Research, Boulder, Colorado, USA

Abstract. The melting of sea ice floes from the edges (lateral melting) results in open water formation and subsequently increases absorption of solar shortwave energy. However, lateral melt plays a small role in the sea ice mass budget in both hemispheres in most climate models (Keen et al., 2020). This is likely influenced by simple parameterizations of this process in sea ice models that are constrained by limited observations. Here we use a coupled climate model (CESM2.0) to assess the sensitivity of modeled sea ice state to the lateral melt parameterization. The results show that sea ice is sensitive both to the parameters determining the effective lateral melt rate, as well as the nuances in how lateral melting is applied to the ice pack. Increasing the lateral melt rate within the range of reasonable values is largely compensated by decreases in the basal melt rate, but can still result in a significant decrease in sea ice concentration and thickness, particularly in the marginal ice zone. We suggest that it is important to consider the efficiency of melt processes at forming open water, which drives the majority of the ice-albedo feedback. Melt processes are more efficient at forming open water in thinner ice scenarios (as we are likely to see in the future), suggesting the importance of well representing thermodynamic evolution. Revisiting model parameterizations of lateral melting with observations will require finding new ways to represent important physical processes.

Madison Smith et al.

Status: open (until 30 Apr 2021)

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  • RC1: 'Comment on tc-2021-67', Anonymous Referee #1, 02 Apr 2021 reply

Madison Smith et al.

Madison Smith et al.

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Short summary
Climate models represent the atmosphere, ocean, sea ice, and land with equations of varying complexity, and are important tools for understanding changes in global climate. Here, we explore how realistic variations in the equations describing how sea ice melt occurs at the edges (called lateral melting) impacts ice and climate. We find that these changes impact the progression of the sea ice-albedo feedback in the Arctic, and so make significant changes to the predicted Arctic sea ice.