Air-Sea Interactions during Cold Air Outbreaks in a coupled Mixed Layer Model
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- Master theses 
Cold air outbreaks play a crucial role in the air-sea heat exchange in high latitudes. To explore the sensitivity to ocean coupling, the role of latent heating and the sensitivity to sea ice distributions in cold air outbreaks, we couple an atmospheric to an oceanic mixed layer model. The mixed layer model of the atmosphere is based on the equations for liquid water potential temperature and the total mixing ratio and the oceanic mixed layer model is based on the equations for temperature and salinity. A steady state is obtained through heat exchange between the atmosphere and ocean, as well as advection in the atmosphere and relaxation toward a climatological state in the ocean. The results show that the coupling with the ocean has only a marginal impact on the atmospheric boundary layer structure, but that cold air outbreaks can lead to an increase in the oceanic mixed layer depth. Latent heating acts to increase the atmopsheric boundary layer growth, which leads a reduction of sensible heat fluxes. We further investigate the effect of different sea ice distributions with and without coupling between the atmosphere and ocean, and show that the sea ice distribution does not change the effect of the cold air outbreak when integrating the fluxes from the ice edge to far downstream the fetch, but it does change the distribution of the fluxes and thereby the local response between the atmosphere and the ocean. The model shows that the oceanic mixed layer depth is deeper when there is a sharper transition from sea ice to open water.
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