Emma Bent

Titre de la thèse : Investigating wave-ice feedbacks in the Arctic Ocean.

Encadrants : Peter Sutherland, Camille Lique and Fabrice Ardhuin

Financements : demi bourses ERC WAAXT et ISblue

Date de début : 04/01/2021

Résumé :
Sea ice in the Arctic Ocean has been decreasing both in thickness and extent since the beginning of the satellite era, and that trend is expected to continue for the next several decades. This means that open-water, as opposed to under-ice, oceanographic processes are becoming increasingly important for Arctic dynamics.
One of the most fundamental differences between the open and ice-covered oceans is the presence of surface waves. As the area of open water in the Arctic increases, well-known fetch relations indicate that a more energetic wave field will develop. Recent work has also shown that during periods of low ice cover, large waves do indeed develop in the Arctic Ocean. Associated to these emerging wave fields are three wave-ice feedback mechanisms: breakup and melting of existing ice by wave motions, increased air-sea fluxes due to wave-driven turbulence which cools the ocean’s surface and contributes to ice thickening, erosion of the halocline by wave-driven turbulence which warms the mixed layer and contributes to ice melting.
The objective of this Ph.D. is to investigate the relative importance of these wave-ice feedback mechanisms in the Arctic Ocean. We will begin with a 1D model (NEMO) coupled with a spectral wave model (WaveWatchIII) to assess the upper ocean mixing in the Arctic Ocean and disentangle the major wave-driven feedbacks, estimating their overall significance. The next step will be to generalize to a 3D set up (coupling waves, ocean and ice) and to use fieldwork observations to compare our results.