Davidson Fraser J. M.

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Davidson
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Fraser J. M.
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  • Preprint
    Rapid circulation of warm subtropical waters in a major glacial fjord in East Greenland
    ( 2009-12-17) Straneo, Fiamma ; Hamilton, Gordon S. ; Sutherland, David A. ; Stearns, Leigh A. ; Davidson, Fraser J. M. ; Hammill, Mike O. ; Stenson, Garry B. ; Rosing-Asvid, Aqqalu
    The recent rapid increase in mass loss from the Greenland Ice Sheet is primarily attributed to an acceleration of outlet glaciers. One possible cause is increased melting at the ice/ocean interface driven by the synchronous warming of subtropical waters offshore of Greenland. This hypothesis is largely untested, however, because of the lack of observations from Greenland’s glacial fjords and our limited understanding of their dynamics. Here, we present new ship-based and moored oceanographic data, collected in Sermilik Fjord, a large glacial fjord in East Greenland, showing that subtropical waters are present throughout the fjord and are continuously replenished via a wind-driven exchange with the shelf, where they occur year-round. The temperature and rapid renewal of these waters suggest that, at present, they drive enhanced submarine melting at the terminus. Key controls on the melting rate are the volume and properties of subtropical waters on the shelf and the patterns of the along-shore winds, suggesting the glaciers’ acceleration was triggered by a combination of atmospheric and oceanic changes. These measurements provide evidence of rapid advective pathway for the transmission of oceanic variability to the ice-sheet margins and highlight an important process that is missing from prognostic ice-sheet models.
  • Article
    Polar ocean observations: A critical gap in the observing system and its effect on environmental predictions from hours to a season
    (Frontiers Media, 2019-08-06) Smith, Gregory C. ; Allard, Richard ; Babin, Marcel ; Bertino, Laurent ; Chevallier, Matthieu ; Corlett, Gary ; Crout, Julia ; Davidson, Fraser J. M. ; Delille, Bruno ; Gille, Sarah T. ; Hebert, David ; Hyder, Patrick ; Intrieri, Janet ; Lagunas, José ; Larnicol, Gilles ; Kaminski, Thomas ; Kater, Belinda ; Kauker, Frank ; Marec, Claudie ; Mazloff, Matthew R. ; Metzger, E. Joseph ; Mordy, Calvin W. ; O’Carroll, Anne ; Olsen, Steffen M. ; Phelps, Michael W. ; Posey, Pamela ; Prandi, Pierre ; Rehm, Eric ; Reid, Philip C. ; Rigor, Ignatius ; Sandven, Stein ; Shupe, Matthew ; Swart, Sebastiaan ; Smedstad, Ole Martin ; Solomon, Amy ; Storto, Andrea ; Thibaut, Pierre ; Toole, John M. ; Wood, Kevin R. ; Xie, Jiping ; Yang, Qinghua ; WWRP PPP Steering Group
    There is a growing need for operational oceanographic predictions in both the Arctic and Antarctic polar regions. In the former, this is driven by a declining ice cover accompanied by an increase in maritime traffic and exploitation of marine resources. Oceanographic predictions in the Antarctic are also important, both to support Antarctic operations and also to help elucidate processes governing sea ice and ice shelf stability. However, a significant gap exists in the ocean observing system in polar regions, compared to most areas of the global ocean, hindering the reliability of ocean and sea ice forecasts. This gap can also be seen from the spread in ocean and sea ice reanalyses for polar regions which provide an estimate of their uncertainty. The reduced reliability of polar predictions may affect the quality of various applications including search and rescue, coupling with numerical weather and seasonal predictions, historical reconstructions (reanalysis), aquaculture and environmental management including environmental emergency response. Here, we outline the status of existing near-real time ocean observational efforts in polar regions, discuss gaps, and explore perspectives for the future. Specific recommendations include a renewed call for open access to data, especially real-time data, as a critical capability for improved sea ice and weather forecasting and other environmental prediction needs. Dedicated efforts are also needed to make use of additional observations made as part of the Year of Polar Prediction (YOPP; 2017–2019) to inform optimal observing system design. To provide a polar extension to the Argo network, it is recommended that a network of ice-borne sea ice and upper-ocean observing buoys be deployed and supported operationally in ice-covered areas together with autonomous profiling floats and gliders (potentially with ice detection capability) in seasonally ice covered seas. Finally, additional efforts to better measure and parameterize surface exchanges in polar regions are much needed to improve coupled environmental prediction.
  • Article
    Atlantic water variability on the SE Greenland continental shelf and its relationship to SST and bathymetry
    (John Wiley & Sons, 2013-02-20) Sutherland, David A. ; Straneo, Fiamma ; Stenson, Garry B. ; Davidson, Fraser J. M. ; Hammill, Mike O. ; Rosing-Asvid, Aqqalu
    Interaction of warm, Atlantic-origin water (AW) and colder, polar origin water (PW) advecting southward in the East Greenland Current (EGC) influences the heat content of water entering Greenland's outlet glacial fjords. Here we use depth and temperature data derived from deep-diving seals to map out water mass variability across the continental shelf and to augment existing bathymetric products. We compare depths derived from the seal dives with the IBCAO Version 3 bathymetric database over the shelf and find differences up to 300 m near several large submarine canyons. In the vertical temperature structure, we find two dominant modes: a cold mode, with the typical AW/PW layering observed in the EGC, and a warm mode, where AW is present throughout the water column. The prevalence of these modes varies seasonally and spatially across the continental shelf, implying distinct AW pathways. In addition, we find that satellite sea surface temperatures (SST) correlate significantly with temperatures in the upper 50 m (R = 0.54), but this correlation decreases with depth (R = 0.22 at 200 m), and becomes insignificant below 250 m. Thus, care must be taken in using SST as a proxy for heat content, as AW mainly resides in these deeper layers.