Melling Humfrey

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Melling
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Humfrey
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  • Article
    Circulation in the vicinity of Mackenzie Canyon from a year-long mooring array
    (Elsevier, 2020-07-04) Lin, Peigen ; Pickart, Robert S. ; Fissel, David ; Ross, Ed ; Kasper, Jeremy L. ; Bahr, Frank B. ; Torres, Daniel J. ; O’Brien, Jeff ; Borg, Keath ; Melling, Humfrey ; Wiese, Francis K.
    Data from a five-mooring array extending from the inner shelf to the continental slope in the vicinity of Mackenzie Canyon, Beaufort Sea are analyzed to elucidate the components of the boundary current system and their variability. The array, part of the Marine Arctic Ecosystem Study (MARES), was deployed from October 2016 to September 2017. Four distinct currents were identified: an eastward-directed flow adjacent to the coast; a westward-flowing, surface-intensified current centered on the outer-shelf; a bottom-intensified shelfbreak jet flowing to the east; and a recirculation at the base of the continental slope within the canyon. The shelf current transports −0.120.03 Sv in the mean and is primarily wind-driven. The response is modulated by the presence of ice, with little-to-no signal during periods of nearly-immobile ice cover and maximum response when there is partial ice cover. The shelfbreak jet transports 0.030.02 Sv in the mean, compared to 0.080.02 Sv measured upstream in the Alaskan Beaufort Sea over the same time period. The loss of transport is consistent with a previous energetics analysis and the lack of Pacific-origin summer water downstream. The recirculation in the canyon appears to be the result of local dynamics whereby a portion of the westward-flowing southern limb of the Beaufort Gyre is diverted up the canyon across isobaths. This interpretation is supported by the fact that the low-frequency variability of the recirculation is correlated with the wind-stress curl in the Canada Basin, which drives the Beaufort gyre.
  • Article
    Dynamics in the deep Canada Basin, Arctic Ocean, inferred by thermistor chain time series
    (American Meteorological Society, 2007-04) Timmermans, Mary-Louise ; Melling, Humfrey ; Rainville, Luc
    A 50-day time series of high-resolution temperature in the deepest layers of the Canada Basin in the Arctic Ocean indicates that the deep Canada Basin is a dynamically active environment, not the quiet, stable basin often assumed. Vertical motions at the near-inertial (tidal) frequency have amplitudes of 10– 20 m. These vertical displacements are surprisingly large considering the downward near-inertial internal wave energy flux typically observed in the Canada Basin. In addition to motion in the internal-wave frequency band, the measurements indicate distinctive subinertial temperature fluctuations, possibly due to intrusions of new water masses.
  • Article
    Toward quantifying the increasing role oceanic heat in sea ice loss in the new Arctic
    (American Meteorological Society, 2015-12) Carmack, Eddy C. ; Polyakov, Igor V. ; Padman, Laurie ; Fer, Ilker ; Hunke, Elizabeth C. ; Hutchings, Jennifer K. ; Jackson, Jennifer M. ; Kelley, Daniel E. ; Kwok, Ron ; Layton, Chantelle ; Melling, Humfrey ; Perovich, Donald K. ; Persson, Ola ; Ruddick, Barry R. ; Timmermans, Mary-Louise ; Toole, John M. ; Ross, Tetjana ; Vavrus, Steve ; Winsor, Peter
    The loss of Arctic sea ice has emerged as a leading signal of global warming. This, together with acknowledged impacts on other components of the Earth system, has led to the term “the new Arctic.” Global coupled climate models predict that ice loss will continue through the twenty-first century, with implications for governance, economics, security, and global weather. A wide range in model projections reflects the complex, highly coupled interactions between the polar atmosphere, ocean, and cryosphere, including teleconnections to lower latitudes. This paper summarizes our present understanding of how heat reaches the ice base from the original sources—inflows of Atlantic and Pacific Water, river discharge, and summer sensible heat and shortwave radiative fluxes at the ocean/ice surface—and speculates on how such processes may change in the new Arctic. The complexity of the coupled Arctic system, and the logistic and technological challenges of working in the Arctic Ocean, require a coordinated interdisciplinary and international program that will not only improve understanding of this critical component of global climate but will also provide opportunities to develop human resources with the skills required to tackle related problems in complex climate systems. We propose a research strategy with components that include 1) improved mapping of the upper- and middepth Arctic Ocean, 2) enhanced quantification of important process, 3) expanded long-term monitoring at key heat-flux locations, and 4) development of numerical capabilities that focus on parameterization of heat-flux mechanisms and their interactions.
  • Article
    Freshwater and its role in the Arctic Marine System : sources, disposition, storage, export, and physical and biogeochemical consequences in the Arctic and global oceans
    (John Wiley & Sons, 2016-03-30) Carmack, Edward C. ; Yamamoto-Kawai, Michiyo ; Haine, Thomas W. N. ; Bacon, Sheldon ; Bluhm, Bodil A. ; Lique, Camille ; Melling, Humfrey ; Polyakov, Igor V. ; Straneo, Fiamma ; Timmermans, Mary-Louise ; Williams, William J.
    The Arctic Ocean is a fundamental node in the global hydrological cycle and the ocean's thermohaline circulation. We here assess the system's key functions and processes: (1) the delivery of fresh and low-salinity waters to the Arctic Ocean by river inflow, net precipitation, distillation during the freeze/thaw cycle, and Pacific Ocean inflows; (2) the disposition (e.g., sources, pathways, and storage) of freshwater components within the Arctic Ocean; and (3) the release and export of freshwater components into the bordering convective domains of the North Atlantic. We then examine physical, chemical, or biological processes which are influenced or constrained by the local quantities and geochemical qualities of freshwater; these include stratification and vertical mixing, ocean heat flux, nutrient supply, primary production, ocean acidification, and biogeochemical cycling. Internal to the Arctic the joint effects of sea ice decline and hydrological cycle intensification have strengthened coupling between the ocean and the atmosphere (e.g., wind and ice drift stresses, solar radiation, and heat and moisture exchange), the bordering drainage basins (e.g., river discharge, sediment transport, and erosion), and terrestrial ecosystems (e.g., Arctic greening, dissolved and particulate carbon loading, and altered phenology of biotic components). External to the Arctic freshwater export acts as both a constraint to and a necessary ingredient for deep convection in the bordering subarctic gyres and thus affects the global thermohaline circulation. Geochemical fingerprints attained within the Arctic Ocean are likewise exported into the neighboring subarctic systems and beyond. Finally, we discuss observed and modeled functions and changes in this system on seasonal, annual, and decadal time scales and discuss mechanisms that link the marine system to atmospheric, terrestrial, and cryospheric systems.