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Honorary Chair awarded to Michael Paul Meredith by the University of Highlands and Islands in recognition of polar research contributions.
This Weddell Sea freshwater budget assessment: - has generated a huge quantity of seawater δ18O data in a region noted for its limited spatial and temporal data coverage. This single project has increased seawater δ18O data for the Weddell Gyre in the public domain by ~40%. - generates a point of reference assessment of the freshwater system in the Weddell Gyre, from which seasonal / inter-annual variability and long-term change can be compared and evaluated in the future. - provides benchmark budget figure to which the global research community can compare model outputs and measurement-based freshwater assessments. - highlights sensitivity of freshwater system in the Weddell Gyre region to underlying deep water circulation.
This ANDREX transient tracer / carbon budget assessment: - has created the first, self-contained measurement-based carbon budget of the Weddell Gyre, that generates a point of reference assessment of the carbonate system in the region from which seasonal / inter-annual variability and long-term change can be compared and evaluated in the future. - highlights the sensitivity of the carbon system in the Weddell Gyre region and the residual air-sea flux to underlying deep water circulation schemes. - has shown the importance of the Weddell Gyre in the global carbon cycle. This is through its role in deep water formation rather than as a location of high annual mean CO2 uptake. Canth is primarily imported into the gyre in surface and mid-depth waters and exported at depth into the global abyss, making the region a critical part of isol...
A multi-year, all-season time series of water column physical properties and sea ice conditions in Ryder Bay, at the western Antarctic Peninsula (WAP), is used to assess the effects on the ocean of varying ice cover. Reduced ice cover leads to increased mixing and heat loss in the winter. The reduction in stratification persists into the following summer, preconditioning the water column to a greater vertical extent of surface-driven mixing. This leads to an increased amount of heat from insolation being mixed down, affecting approximately the top 100m. The increased heat uptake in summer exceeds the heat lost the preceding winter, giving the initially counter-intuitive effect that enhanced winter cooling generates warmer temperatures in the following summer and autumn. This process is therefore a positive feedback on sea ice, as reduc...
A large phytoplankton bloom occurs downstream of South Georgia, an island on the northern edge of the Scotia Sea, Atlantic sector of the Southern Ocean. This is due to natural iron fertilisation being advected downstream in the Antarctic Circumpolar Current. Mapping of SeaWiFS chl-a in dynamic height/longitude space reveals the trajectory of surface water under the dual influences of geostrophic flow and Ekman flux. A theoretical estimate of the trajectory shows good agreement with observations. The trajectory is dependent on the wind stress:mixed layer depth ratio, but independent of the latitudinal separation of dynamic height contours. The chl-a distribution suggests that iron reaches 20°W below the mixed layer, away from the effects of Ekman flux, but beyond the iron is confined to the surface layer. Chl-a reduces monotonically eas...
Executive Summary The Southern Ocean provides the principal connection between the Earth’s ocean basins and between the upper and lower layers of the global ocean circulation. As a result, the Southern Ocean strongly influences climate patterns and the cycling of carbon and nutrients. Changes in the Southern Ocean would therefore have global ramifications. Limited observations suggest the Southern Ocean is indeed changing: the region is warming more rapidly than the global ocean average; salinity changes driven by changes in precipitation and ice melt have been observed in both the upper and abyssal ocean; the uptake of carbon by the Southern Ocean has slowed the rate of climate change but increased the acidity of the ocean; and Southern Ocean ecosystems are reacting to changes in the physical and chemical environment. However...
Signals in sea-level or, more properly, sub-surface pressure (SSP; sea-level corrected for the inverse barometer effect) are expected to propagate rapidly along the continental slope due to the effect of sloping topography on wave modes, resulting in strongly correlated SSP over long-distances. Observations of such correlations around the Arctic and Antarctic are briefly reviewed, and then extended using satellite altimetry to the rest of the global continental slope. It is shown that such long.-distance correlations are common, especially in extra-tropical regions. Simple correlations from altimetry cannot., however, establish the wave speed., or whether waves are responsible for the correlations as opposed to large-scale coherence in the forcing. A case study, around South America is used to highlight some of the complications, and i...
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