Sea ice dynamics are highly complex and generally poorly resolved by sea ice models.  This is problematic, as they modulate the amount of momentum exchanged between the atmosphere and the ocean in polar regions, as well as play a key role in heat and light fluxes through the opening/closing of sea ice leads.  A solution to improve simulated sea ice dynamics is to use a brittle rheology to represent the mechanical behaviour of sea ice. Such rheology is included in the sea ice model neXtSIM, and we demonstrated its ability to capture the
observed characteristics and complexity of fine-scale sea ice deformations. Here, we present two cases where we coupled this sea ice model to better understand the role of ice dynamics in ice-ocean interactions.
In the first case, we set up a 12km resolution ocean–sea-ice coupled model, using OPA, the ocean component of NEMO. We investigate the sea ice mass balance of the model for the period 2000-2018. After evaluating the modelled sea ice against available observations (extent, drift, volume, deformations, etc.), we estimate the contribution of leads and polynyas to winter ice production. We find this contribution to add up from 25% to 35% of the total ice growth in pack ice in winter, showing a significant increase over the 18 years covered by the model simulation.
In the second case, we focus on the marginal ice zone (MIZ) and couple neXtSIM with the wave model WAVEWATCH III. We use this configuration to investigate how wave-induced breakup impacts sea ice dynamics in the MIZ. We show how, using the “damage” quantity that is at the core of the brittle rheology framework, we can represent the loss of ice strength associated with wave-induced breakup, and how breakup can increase the mobility of the thickest ice in the MIZ after storms.

Date & Time: Tue Nov 19 2024 11:00:00 GMT+0100 (Central European Standard Time)
Room: salle du LOCEAN, couloir 45-55, 4ème étage, pièce 417