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Abstract:
Mesoscale atmosphere-ocean interaction processes in the Arctic, such as marine cold air outbreaks (MCAOs), are often poorly represented in weather and climate prediction models. Yet, the energy exchange associated with these events can have a significant impact on the atmospheric heat and water content, as well as the ocean mixed layer. In the Nordic Seas, where crucial warm-to-cold water mass transformation occurs, MCAOs have a significant effect on the Atlantic Meridional Overturning Circulation. However, the processes through which MCAOs affect this water mass transformation and the ocean circulation remain unclear, with possible competing effects occurring in the boundary currents and in the interior of the Nordic Seas. We investigate the impact of air-sea heat exchange during MCAOs events in the Nordic Seas, shedding light on the role of MCAOs on water mass properties and dynamics. We use a combination of atmospheric (ERA5) and ocean (TOPAZ4, GLORYS12) reanalyses data to characterize the spatial dependence of the ocean response to MCAOs. By classifying the events according to their location, intensity, and duration, we focus on the ocean response in terms of heat and salt content, stratification, as well as dynamics. We propose mechanisms linking the atmosphere-ocean energy exchanges during MCAOs to the concomitant changes in the boundary current regions and the interior region of the Nordic Seas.
