Recent community reports on autonomous and Lagrangian platforms and Arctic observing identify the development of under-ice navigation and telemetry technologies as one of the critical factors limiting the scope of high-latitude measurement efforts. An NSF-sponsored workshop will address these needs, bringing together international participants from the fields of acoustic navigation and telemetry, arctic oceanography, acoustical oceanography and autonomous platforms. Workshop participants will begin the coordinated definition of an acoustic navigation and telemetry system capable of supporting a diverse range of Arctic observational activities. Efforts will focus on comprehensive system design, including specifications for components comprised of mature technologies and identification of areas requiring additional development. MORE »

As part of a coordinated international effort to quantify (and eventually monitor) the variability of fluxes connecting the Arctic and Atlantic Oceans and to understand the role played by the Arctic and sub-Arctic in steering decadal scale climate variability, an integrated observing system consisting of moorings and gliders will provide year-round measurements of volume, liquid freshwater and ice fluxes across Davis Strait. Fluxes through the Strait represent the net integrated Canadian Archipelago throughflow, modified by terrestrial inputs and oceanic processes during its southward transit through Baffin Bay. By the time they reach Davis Strait, Arctic waters already embody most of the transformation they undergo prior to exerting their influence on the deepwater formation sites in the Labrador Sea. This makes the Strait an ideal site for monitoring temporal and spatial variability in the critical upstream boundary condition for Labrador Sea convection. Measurements at Davis Strait will be used to study how fluctuations in the Arctic freshwater system modulate deep water formation to the south, thus influencing the associated meridional overturning circulation (MOC). MORE »

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The West Wind Drift feeds both the California and Alaska Currents, providing a pathway for exchange between the subarctic and subtropical gyres. Its bifurcation at the eastern boundary is known qualitatively but not particularly quantitatively. The relative proportions of waters returning poleward and those continuing equatorward is a matter of speculation due to a relatively sparse observational base incapable of resolving the space-time structure of the eastern boundary current formation. Seasonal and interannual changes in stratification in a broad region off the Pacific Northwest coast are recognized, but their causes and links to flow variation are largely unknown. Seagliders will operate year-round, occupying repeated hydrographic sections across the northern reaches of the California Current system. These measurements will characterize the seasonal evolution of the eastern boundary current system off the Washington coast.

Recent ONR-funded investigations have focused on regions bounded by progressively more complex topography (e.g. Arabian Sea, Japan/East Sea and Adriatic Sea) where orographic effects produce intense, small-scale atmospheric forcing. Small-scale wind- and buoyancy-forcing, combined with riverine input, complex bathymetry and proximity to the coastal boundary, support a wide variety of energetic fronts, filaments and eddies. These features have short temporal and spatial scales and can play critical roles in governing basin-scale circulation, cross-shelf transport, watermass transformation and subduction. Two cruises in the Northern and Central Adriatic Sea conducted quasi-synoptic, three-dimensional surveys of mesocale and submesoscale physical and optical variability, following their response to strong forcing events. During winter (February), sampling emphasized the response to episodic Bora wind events. Although springtime (May) measurement program was designed to sample during the Po River spring freshette, freshwater discharge rates were more than a standard deviation below the 12-year mean and winds remained weak throughout the survey period, leading to a study of weakly forced dynamics in a strongly stratified, shallow water regime. MORE »

As part of the U.S. GLOBEC Northeast Pacific program, repeated Seaglider surveys will characterize the seasonal and interannual variability of the Alaska coastal Current (ACC). The dynamics of the Alaska Coastal Current (ACC) govern stratification and circulation over the inner portion of the Alaskan shelf, a region that plays a critical role in the early life history of several commercially important fish species, including juvenile salmon. The system responds strongly to large seasonal and interannual changes in freshwater discharge and wind-forcing. Moreover, seasonal shifts in dynamics likely exert strong influences on the temporal and spatial structure of stratification, on the spring phytoplankton bloom and on the advective transport of zooplankton and fish. Seasonal cycles in dynamics may also play a key role in explaining how nutrients are replenished in this downwelling-favorable system that is inundated by nutrient-deplete freshwater discharge. Thus, variability in wind-forcing and freshwater discharge produce significant changes in ACC dynamics which can influence the recruitment success of zooplankton and fish through a number of different pathways. MORE »

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