Wood Michael

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Last Name
Wood
First Name
Michael
ORCID
0000-0003-3074-7845

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  • Article
    BedMachine v3 : complete bed topography and ocean bathymetry mapping of Greenland from multibeam echo sounding combined with mass conservation
    (John Wiley & Sons, 2017-11-01) Morlighem, Mathieu ; Williams, Chris N. ; Rignot, Eric ; An, Lu ; Arndt, Jan Erik ; Bamber, Jonathan L. ; Catania, Ginny ; Chauché, Nolwenn ; Dowdeswell, Julian ; Dorschel, Boris ; Fenty, Ian ; Hogan, Kelly ; Howat, Ian M. ; Hubbard, Alun ; Jakobsson, Martin ; Jordan, Tom M. ; Kjeldsen, Kristian K. ; Millan, Romain ; Mayer, Larry A. ; Mouginot, Jeremie ; Noël, Brice P. Y. ; O’Cofaigh, Colm ; Palmer, Steven ; Rysgaard, Soren ; Seroussi, Helene ; Siegert, Martin J. ; Slabon, Patricia ; Straneo, Fiamma ; Van den Broeke, Michiel ; Weinrebe, W. ; Wood, Michael ; Zinglersen, Karl Brix
    Greenland's bed topography is a primary control on ice flow, grounding line migration, calving dynamics, and subglacial drainage. Moreover, fjord bathymetry regulates the penetration of warm Atlantic water (AW) that rapidly melts and undercuts Greenland's marine-terminating glaciers. Here we present a new compilation of Greenland bed topography that assimilates seafloor bathymetry and ice thickness data through a mass conservation approach. A new 150 m horizontal resolution bed topography/bathymetric map of Greenland is constructed with seamless transitions at the ice/ocean interface, yielding major improvements over previous data sets, particularly in the marine-terminating sectors of northwest and southeast Greenland. Our map reveals that the total sea level potential of the Greenland ice sheet is 7.42 ± 0.05 m, which is 7 cm greater than previous estimates. Furthermore, it explains recent calving front response of numerous outlet glaciers and reveals new pathways by which AW can access glaciers with marine-based basins, thereby highlighting sectors of Greenland that are most vulnerable to future oceanic forcing.
  • Article
    Characteristic depths, fluxes and timescales for Greenland’s tidewater glacier fjords from subglacial discharge‐driven upwelling during summer
    (American Geophysical Union, 2022-03-02) Slater, Donald A. ; Carroll, Dustin ; Oliver, Hilde ; Hopwood, Mark J. ; Straneo, Fiamma ; Wood, Michael ; Willis, Joshua K. ; Morlighem, Mathieu
    Greenland's glacial fjords are a key bottleneck in the earth system, regulating exchange of heat, freshwater and nutrients between the ice sheet and ocean and hosting societally important fisheries. We combine recent bathymetric, atmospheric, and oceanographic data with a buoyant plume model to show that summer subglacial discharge from 136 tidewater glaciers, amounting to 0.02 Sv of freshwater, drives 0.6–1.6 Sv of upwelling. Bathymetric analysis suggests that this is sufficient to renew most major fjords within a single summer, and that these fjords provide a path to the continental shelf that is deeper than 200 m for two-thirds of the glaciers. Our study provides a first pan-Greenland inventory of tidewater glacier fjords and quantifies regional and ice sheet-wide upwelling fluxes. This analysis provides important context for site-specific studies and is a step toward implementing fjord-scale heat, freshwater and nutrient fluxes in large-scale ice sheet and climate models.
  • Article
    Export of ice sheet meltwater from Upernavik Fjord, West Greenland
    (American Meteorological Society, 2022-03-01) Muilwijk, Morven ; Straneo, Fiamma ; Slater, Donald A. ; Smedsrud, Lars H. ; Holte, James W. ; Wood, Michael ; Andresen, Camilla S. ; Harden, Benjamin E.
    Meltwater from Greenland is an important freshwater source for the North Atlantic Ocean, released into the ocean at the head of fjords in the form of runoff, submarine melt, and icebergs. The meltwater release gives rise to complex in-fjord transformations that result in its dilution through mixing with other water masses. The transformed waters, which contain the meltwater, are exported from the fjords as a new water mass Glacially Modified Water (GMW). Here we use summer hydrographic data collected from 2013 to 2019 in Upernavik, a major glacial fjord in northwest Greenland, to describe the water masses that flow into the fjord from the shelf and the exported GMWs. Using an optimum multi-parameter technique across multiple years we then show that GMW is composed of 57.8% ± 8.1% Atlantic Water (AW), 41.0% ± 8.3% Polar Water (PW), 1.0% ± 0.1% subglacial discharge, and 0.2% ± 0.2% submarine meltwater. We show that the GMW fractional composition cannot be described by buoyant plume theory alone since it includes lateral mixing within the upper layers of the fjord not accounted for by buoyant plume dynamics. Consistent with its composition, we find that changes in GMW properties reflect changes in the AW and PW source waters. Using the obtained dilution ratios, this study suggests that the exchange across the fjord mouth during summer is on the order of 50 mSv (1 Sv ≡ 106 m3 s−1) (compared to a freshwater input of 0.5 mSv). This study provides a first-order parameterization for the exchange at the mouth of glacial fjords for large-scale ocean models.
  • Article
    Greenland Subglacial Discharge as a driver of hotspots of increasing coastal chlorophyll since the early 2000s
    (American Geophysical Union, 2023-05-18) Oliver, Hilde ; Slater, Donald ; Carroll, Dustin ; Wood, Michael ; Morlighem, Mathieu ; Hopwood, Mark J.
    Subglacial discharge emerging from the base of Greenland's marine‐terminating glaciers drives upwelling of nutrient‐rich bottom waters to the euphotic zone, which can fuel nitrate‐limited phytoplankton growth. Here, we use buoyant plume theory to quantify this subglacial discharge‐driven nutrient supply on a pan‐Greenland scale. The modeled nitrate fluxes were concentrated in a few critical systems, with half of the total modeled nitrate flux anomaly occurring at just 14% of marine‐terminating glaciers. Increasing subglacial discharge fluxes results in elevated nitrate fluxes, with the largest flux occurring at Jakobshavn Isbræ in Disko Bay, where subglacial discharge is largest. Subglacial discharge and nitrate flux anomaly also account for significant temporal variability in summer satellite chlorophyll a (Chl) within 50 km of Greenland's coast, particularly in some regions in central west and northwest Greenland.Runoff and modeled nitrate upwelling can explain temporal variability in surface cholorophyll in some coastal areas in west Greenland