COSMUS

Departure from Port Stanley (51° 41' S 57° 51' W), straight line towards southern Weddell Sea, Filchner Trough (roughly 76° 48’ S, 34° 31’ W), continental shelf break towards the west (~ 44°W) and back to Port Stanley via Neumayer III Station. Expedition to the southern Weddell Sea (Filchner Trough) in collaboration with scientists from France, Norway, and Switzerland. Scientific goals are (a) quantifying the fluxes of heat and salt across the continental shelf break and (b) the carbon flux from the sea-ice controlled surface to the abyss. Participating groups cover sea-ice physics and biology, physical oceanography, bio-geo-chemistry, marine mammals, pelagic fluxes, benthic fluxes and fauna, microplastic, and bathymetry.

Important goals of the expedition PS124 (COSMUS) are: • Characterisation of hydrographic features and water masses of the Filchner-Ronne Outflow System, the role of bathymetry for current pathways, and the deep and bottom water formation rates at the continental slope. • Monitoring time variations of hydrographic conditions on the eastern flank of the Filchner Trough by means of re-deployment of 3 moorings at 76°S, complemented by 3 additional moorings, and (re)-deployment of several moorings near the Filchner Trough sill in cooperation with institutes from Norway and France. • Wide-range hydrographic profiling during austral winter west of the Filchner Trough by means of CTD-tagged Weddell Seals. • Quantification of the Antarctic continental shelf’s contribution to global carbon and nutrient/iron budgets, assessing the biological carbon pump by dissecting biotic and abiotic controls of ocean productivity and carbon exports from the surface ocean to the deep. • Understanding and predicting the change of marine biological diversity and assessing the risk for critical transitions in marine ecosystem functionality. • Investigation of the biological production of the Filchner Trough region and the high-energy turnover to subsequent trophic levels. • Estimating the impact of possible changes in the hydrography and shelf and sea ice dynamics on biodiversity and ecosystem functioning of the southern Weddell Sea. • Compilation of data on distribution patterns of pack ice seals in the Filchner Trough region. • Describing the sea ice in front of the Filchner-Ronne Ice Shelf (FRIS) by measuring salinity, drift velocity and other physical parameters together with a sea ice buoy programme. • Investigation of the geochemical content of the sediments. • Measuring the micro-plastic content of seawater in the southern Weddell Sea.