Results

(This section will be fed by results as the project advances)

Development of Bottom Following Deep Floats

First pool tests of the prototype were performed at IFREMER pool, and were successful. Further software adjustments are to be made before first "real-world" test deployment in the Mediterranean later this year (2016).

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The ocean mixed layer under Southern Ocean sea-ice: seasonal cycle and forcing​

Pellichero, V., Sallée, J.B., Schmidtko, S., Roquet, F., Charrassin, J.B., 2016, submitted to JGR

The mixed-layer at the surface of the ocean is the gateway for all exchanges between air and sea. A vast area of the Southern Ocean is however seasonally capped by sea-ice, which alters this gateway and the characteristic the ocean mixed-layer. The interaction between the ocean mixed-layer and seaice plays a key role for water-mass formation and circulation, carbon cycle, sea-ice dynamics, and ultimately for the climate as a whole. However, the structure and characteristics of the mixed layer, as well as the processes responsible for its evolution, are poorly understood due to the lack of in-situ observations and measurements. We urgently need to better understand the forcing and the characteristics of the ocean mixed-layer under sea-ice if we are to understand and predict the worlds climate. In this study, we combine a range of distinct sources of observation to overcome this lack in our understanding of the Polar Regions. Working on Elephant Seal-derived data as well as ship-based observations and Argo float data, we describe the seasonal cycle of the characteristics and stability of the ocean mixed layer over the entire Southern Ocean (South of 40◦S), and specifically under sea-ice. Here you can see for instance the seasonal cycle of the salinity. Under sea-ice and close to the continent, we observe a salinity increase in the surface layer in fall and winter associated with brine rejection from ice formation:

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Mixed-layer budgets of heat and freshwater are used to investigate the main forcings of the mixed-layer seasonal cycle. The seasonal variability of sea surface salinity and temperature are primarily driven by surface processes, dominated by sea-ice freshwater flux for the salt budget, and by air-sea flux for the heat budget. Ekman advection, vertical diffusivity and vertical entrainment play only secondary role. Our results suggest that changes in regional sea-ice distribution or sea-ice seasonal cycle duration, as currently observed, would widely affect the buoyancy budget of the underlying mixed-layer, and impacts large-scale water-mass formation and transformation.



Water-mass transformation and Pathways In The Weddell Sea: uncovering the dynamics of a global climate chokepoint from In-situ measurements. 


Wapiti is a European funded project aimed at exploring the regional water-mass pathways in the Weddell Sea: an unchartered cornerstone for understanding the polar ocean circulation and its links to global climate.

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