Water properties, heat and volume fluxes of Pacific water in Barrow Canyon during summer 2010

Itoh, Motoyo; Pickart, Robert S.; Kikuchi, Takashi; Fukamachi, Yasushi; Ohshima, Κay I.; Simizu, Daisuke; Arrigo, Kevin R.; Vagle, Svein; He, Jianfeng; Ashjian, Carin J.; Mathis, Jeremy T.; Nishino, Shigeto; Nobre, Carolina

doi:10.1016/j.dsr.2015.04.004

Cited by 46 publications

(56 citation statements)

References 40 publications

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“…During our late spring survey, however, the majority of the water on the northeast Chukchi shelf was NVWW (Figure a). Here, we define NVWW as colder than −1.6 °C and saltier than 31.5, a definition consistent with past studies (e.g., Gong & Pickart, ; Itoh et al, ; Pickart et al, ). As noted in section , NVWW can be further transformed within the northeast Chukchi polynya to form a very salty water mass known as hypersaline winter water.…”

Section: Resultsmentioning

confidence: 83%

Characteristics and Transformation of Pacific Winter Water on the Chukchi Sea Shelf in Late Spring

et al. 2019

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Data from a late spring survey of the northeast Chukchi Sea are used to investigate various aspects of newly ventilated winter water (NVWW). More than 96% of the water sampled on the shelf was NVWW, the saltiest (densest) of which tended to be in the main flow pathways on the shelf. Nearly all of the hydrographic profiles on the shelf displayed a two‐layer structure, with a surface mixed layer and bottom boundary layer separated by a weak density interface (on the order of 0.02 kg/m3). Using a polynya model to drive a one‐dimensional mixing model, it was demonstrated that, on average, the profiles would become completely homogenized within 14–25 hr when subjected to the March and April heat fluxes. A subset of the profiles would become homogenized when subjected to the May heat fluxes. Since the study domain contained numerous leads within the pack ice—many of them refreezing—and since some of the measured profiles were vertically uniform in density, this suggests that NVWW is formed throughout the Chukchi shelf via convection within small openings in the ice. This is consistent with the result that the salinity signals of the NVWW along the central shelf pathway cannot be explained solely by advection from Bering Strait or via modification within large polynyas. The local convection would be expected to stir nutrients into the water column from the sediments, which explains the high nitrate concentrations observed throughout the shelf. This provides a favorable initial condition for phytoplankton growth on the Chukchi shelf.

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Section: Resultsmentioning

confidence: 83%

Characteristics and Transformation of Pacific Winter Water on the Chukchi Sea Shelf in Late Spring

et al. 2019

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“…In the summer, WW is increasingly modified through solar heating and/or lateral mixing (e.g., Gong & Pickart, ) and biological activity (Lowry et al, ), and is eventually transported northward to the deep Arctic basin. This occurs via advection through Barrow Canyon (Gong & Pickart, ; Itoh et al, ; Woodgate et al, ) and Herald Canyon (Pickart et al, ). WW is also fluxed offshore via turbulent processes such as eddy formation in the two canyons (Pickart et al, ; Pisareva et al, ) and eddy generation from the shelfbreak jet along the Chukchi and Beaufort Seas (Mathis et al, ; Spall et al, ).…”

Section: Introductionmentioning

confidence: 99%

Under‐Ice Phytoplankton Blooms Inhibited by Spring Convective Mixing in Refreezing Leads

et al. 2018

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Spring phytoplankton growth in polar marine ecosystems is limited by light availability beneath ice‐covered waters, particularly early in the season prior to snowmelt and melt pond formation. Leads of open water increase light transmission to the ice‐covered ocean and are sites of air‐sea exchange. We explore the role of leads in controlling phytoplankton bloom dynamics within the sea ice zone of the Arctic Ocean. Data are presented from spring measurements in the Chukchi Sea during the Study of Under‐ice Blooms In the Chukchi Ecosystem (SUBICE) program in May and June 2014. We observed that fully consolidated sea ice supported modest under‐ice blooms, while waters beneath sea ice with leads had significantly lower phytoplankton biomass, despite high nutrient availability. Through an analysis of hydrographic and biological properties, we attribute this counterintuitive finding to springtime convective mixing in refreezing leads of open water. Our results demonstrate that waters beneath loosely consolidated sea ice (84–95% ice concentration) had weak stratification and were frequently mixed below the critical depth (the depth at which depth‐integrated production balances depth‐integrated respiration). These findings are supported by theoretical model calculations of under‐ice light, primary production, and critical depth at varied lead fractions. The model demonstrates that under‐ice blooms can form even beneath snow‐covered sea ice in the absence of mixing but not in more deeply mixed waters beneath sea ice with refreezing leads. Future estimates of primary production should account for these phytoplankton dynamics in ice‐covered waters.

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“…Driven by the Arctic‐North Pacific sea surface height difference, the Bering Strait inflow carries Pacific water into the Chukchi Sea [ Aagaard et al ., ] and divides into several flow branches [ Weingartner et al ., ]. In summer, a large portion of the inflowing Pacific water drains into the Canada Basin through Barrow Canyon [ Itoh et al ., ; Gong and Pickart , ; Pickart et al ., ], much of it via the Alaskan Coastal Current (ACC) which flows northeastward along the Alaskan coast (Figure ) [ Paquette and Bourke , ; Weingartner et al ., ].…”

Section: Introductionmentioning

confidence: 99%

Seasonal variation of the Beaufort shelfbreak jet and its relationship to Arctic cetacean occurrence

Lin

Pickart

Stafford

et al. 2016

J. Geophys. Res. Oceans

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Using mooring time series from September 2008 to August 2012, together with ancillary atmospheric and satellite data sets, we quantify the seasonal variations of the shelfbreak jet in the Alaskan Beaufort Sea and explore connections to the occurrences of bowhead and beluga whales. Wind patterns during the 4 year study period are different from the long‐term climatological conditions that the springtime peak in easterly winds shifted from May to June and the autumn peak was limited to October instead of extending farther into the fall. These changes were primarily due to the behavior of the two regional atmospheric centers of action, the Aleutian Low and Beaufort High. The volume transport of the shelfbreak jet, which peaks in the summer, was decomposed into a background (weak wind) component and a wind‐driven component. The wind‐driven component is correlated to the Pt. Barrow, AK alongcoast wind speed record although a more accurate prediction is obtained when considering the ice thickness at the mooring site. An upwelling index reveals that wind‐driven upwelling is enhanced in June and October when storms are stronger and longer‐lasting. The seasonal variation of Arctic cetacean occurrence is dominated by the eastward migration in spring, dictated by pack‐ice patterns, and westward migration in fall, coincident with the autumn peak in shelfbreak upwelling intensity.

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Water properties, heat and volume fluxes of Pacific water in Barrow Canyon during summer 2010

Cited by 46 publications

References 40 publications

Characteristics and Transformation of Pacific Winter Water on the Chukchi Sea Shelf in Late Spring

Characteristics and Transformation of Pacific Winter Water on the Chukchi Sea Shelf in Late Spring

Under‐Ice Phytoplankton Blooms Inhibited by Spring Convective Mixing in Refreezing Leads

Seasonal variation of the Beaufort shelfbreak jet and its relationship to Arctic cetacean occurrence

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