Abstract
Sea ice formation processes occur on subgrid scales, and the detailed physics describing the processes are therefore not generally represented in climate models. One likely consequence of this is the premature closing of areas of open water in model simulations, which may result in a misrepresentation of heat and gas exchange between the ocean and atmosphere. This work demonstrates the implementation of a more realistic model of sea ice formation, introducing grease ice as a wind and oceanic stress‐dependent intermediary state between water and new sea ice. We use the fully coupled land‐atmosphere‐ocean‐sea ice model, HadGEM3‐GC3.1 and perform a three‐member ensemble with the new grease ice scheme from 1964 to 2013. Comparing our sea ice results with the existing ensemble without grease ice formation shows an increase in sea ice thickness and volume in the Arctic. In the Antarctic, including grease ice processes results in large local changes to both simulated sea ice concentration and thickness, but no change to the total area or volume.
Plain Language Summary
The way that new sea ice forms in most climate models may result in new sea ice forming more quickly than it does in reality, prematurely closing areas of open water that are important to heat and gas exchange between the ocean and atmosphere, and impacting the albedo, and therefore the radiation budget, of the planet. In this work, we implement a more realistic representation of how new sea ice forms in a fully coupled climate model, and demonstrate the effect using an ensemble of historical climate simulations.
Key Points
A more detailed representation of sea ice formation was implemented in a coupled climate model ensemble
Including grease ice processes resulted in increased Arctic sea ice thickness and volume
Including grease ice processes resulted in large local changes to Antarctic winter sea ice concentration and thickness