Particle flux on the continental shelf in the Amundsen Sea Polynya and Western Antarctic Peninsula

Ducklow, Hugh W.; Wilson, Stephanie E.; Post, Anton F.; Stammerjohn, Sharon; Erickson, Michelle A.; Lee, Sanghoon; Lowry, Kate E.; Sherrell, Robert M.; Yager, Patricia L.

doi:10.12952/journal.elementa.000046

Cited by 54 publications

(81 citation statements)

References 76 publications

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“…This work underscores the need for improved and coordinated in situ time series observations of air-ocean-ice interactions, coupled with continued improvements in satellite-derived products and high-resolution ocean models. Although acquiring in situ observations is challenging, given the highly dynamic nature of Antarctic sea ice, newer, cost-effective and more sophisticated technologies (e.g., autonomous vehicles and moored instrumentation) are now making such observations possible (Schofield et al, 2010(Schofield et al, , 2015Maksym et al, 2012;Smith et al, 2014;Ackley et al, 2015;Ducklow et al, 2015). By joining these efforts, we will better resolve cause and effect and better assess future changes to this highly sensitive and rapidly changing marine environment.…”

Section: Discussionmentioning

confidence: 99%

Seasonal sea ice changes in the Amundsen Sea, Antarctica, over the period of 1979–2014

Stammerjohn

Maksym

Massom

et al. 2015

Elementa: Science of the Anthropocene

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Recent attention has focused on accelerated glacial losses along the Amundsen Sea coast that result from changes in atmosphere and ocean circulation, with sea ice playing a mediating but not well-understood role. Here, we investigated how sea ice has changed in the Amundsen Sea over the period of 1979 to 2014, focusing on spatio-temporal changes in ice edge advance/retreat and percent sea ice cover in relation to changes in winds. In contrast to the widespread sea ice decreases to the east and increases to the west of the Amundsen Sea, sea ice changes in the Amundsen Sea were confined to three areas: (i) offshore of the shelf break, (ii) the southern Pine Island Polynya, and (iii) the eastern Amundsen Sea Polynya. Offshore, a 2-month decrease in ice season duration coincided with seasonal shifts in wind speed and direction from March to May (relating to later ice advance) and from September to August (relating to earlier retreat), consistent with reported changes in the depth/location of the Amundsen Sea Low. In contrast, sea ice decreases in the polynya areas corresponded to episodic or step changes in spring ice retreat (earlier by 1-2 months) and were coincident with changes to Thwaites Iceberg Tongue (located between the two polynyas) and increased southeasterly winds. Temporal correlations among these three areas were weak, indicating different local forcing and/or differential response to large-scale forcing. Although our analysis has shown that part of the variability can be explained by changes in winds or to the coastal icescape, an additional but unknown factor is how sea ice has responded to changes in ocean heat and freshwater inputs. Unraveling cause and effect, critical for predicting changes to this rapidly evolving ocean-ice shelf-sea ice system, will require in situ observations, along with improved remote sensing capabilities and ocean modeling.

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Section: Discussionmentioning

confidence: 99%

Seasonal sea ice changes in the Amundsen Sea, Antarctica, over the period of 1979–2014

Stammerjohn

Maksym

Massom

et al. 2015

Elementa: Science of the Anthropocene

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“…4). At this site, the sea ice concentration decreased to nearly nonexistent levels in November 2010, and the ice-free condition was maintained for over 3 months from midNovember to the end of February (Ducklow et al, 2015). The ice concentration afterward fluctuated between $ 30% and 90%.…”

Section: Spatial Variation Of Poc Fluxmentioning

confidence: 91%

“…The pH of the solution in the sampling bottles was not determined upon recovery. The US ASPIRE sediment trap (Technicap, cylindrical type) was deployed at a 350 m depth inside the polynya (73.821S, 113.071W; 785 m water depth (Ducklow et al, 2015)). …”

Section: Methodsmentioning

confidence: 99%

“…The ice concentration afterward fluctuated between $ 30% and 90%. The highest POC flux was observed in early January when an intense but short-lived pulse of enhanced POC export (up to 96 mgC m À 2 d À 1 ), apparently due to a phytoplankton bloom, was registered by the trap (Ducklow et al, 2015). The peak flux of sinking POC inside the polynya was about twice that in the SIZ.…”

Section: Spatial Variation Of Poc Fluxmentioning

confidence: 96%

“…We describe the detailed results of the sinking particle samples in the SIZ only. Then we compare our results with those obtained from sinking particle samples collected at a 350 m depth inside the polynya by the US Amundsen Sea Polynya International Research Expedition (ASPIRE, (Ducklow et al, 2015)). …”

Section: Introductionmentioning

confidence: 99%

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Sinking particle flux in the sea ice zone of the Amundsen Shelf, Antarctica

Kim¹,

Hwang²,

Kim³

et al. 2015

Deep Sea Research Part I: Oceanographic Research Papers

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a b s t r a c tWe have examined the flux, biogenic composition, and isotopic values of sinking particles collected by a time-series sediment trap deployed in the sea ice zone (SIZ) of the Amundsen Sea from January 2011 for 1 year. The major portion of the particle flux occurred during the austral summer in January and February when sea ice concentration was reduced to o 60%. Biogenic components, dominated by opal ( $ 78% of the biogenic components), accounted for over 75% of particle flux during this high-flux period. The dominant source of sinking particles shifted from diatoms to soft-tissued organisms, evidenced by high particulate organic carbon (POC) content ( 430%) and a low bio-Si/POC ratio (o 0.5) during the austral winter. CaCO 3 content and its contribution to total particle flux was low ( $ 6%) throughout the study period. Aged POC likely supplied from sediment resuspension accounted for a considerable fraction only from October to December, which was evidenced by a low radiocarbon content and relatively high (30-50%) content of the non-biogenic components. When compared with POC flux inside the Amundsen Sea polynya obtained by the US Amundsen Sea Polynya International Research Expedition (ASPIRE), the POC flux integrated over the austral summer in the SIZ was virtually identical, although the maximum POC flux was approximately half that inside the Amundsen Sea polynya. This comparatively high POC flux integrated over the austral summer in the SIZ may be caused by phytoplankton blooms persisting over a longer periods and more efficient export of organic matter potentially owing to the diatom-dominant plankton community. If this observation is a general phenomenon on the Amundsen Shelf, the role of the SIZ, compared with the polynyas, need to be examined more carefully when trying to characterize the POC export in this region.

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Dynamic Biological Functioning Important for Simulating and Stabilizing Ocean Biogeochemistry

Buchanan

Matear

Chase

et al. 2018

Global Biogeochemical Cycles

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The biogeochemistry of the ocean exerts a strong influence on the climate by modulating atmospheric greenhouse gases. In turn, ocean biogeochemistry depends on numerous physical and biological processes that change over space and time. Accurately simulating these processes is fundamental for accurately simulating the ocean's role within the climate. However, our simulation of these processes is often simplistic, despite a growing understanding of underlying biological dynamics. Here we explore how new parameterizations of biological processes affect simulated biogeochemical properties in a global ocean model. We combine 6 different physical realizations with 6 different biogeochemical parameterizations (36 unique ocean states). The biogeochemical parameterizations, all previously published, aim to more accurately represent the response of ocean biology to changing physical conditions. We make three major findings. First, oxygen, carbon, alkalinity, and phosphate fields are more sensitive to changes in the ocean's physical state. Only nitrate is more sensitive to changes in biological processes, and we suggest that assessment protocols for ocean biogeochemical models formally include the marine nitrogen cycle to assess their performance. Second, we show that dynamic variations in the production, remineralization, and stoichiometry of organic matter in response to changing environmental conditions benefit the simulation of ocean biogeochemistry. Third, dynamic biological functioning reduces the sensitivity of biogeochemical properties to physical change. Carbon and nitrogen inventories were 50% and 20% less sensitive to physical changes, respectively, in simulations that incorporated dynamic biological functioning. These results highlight the importance of a dynamic biology for ocean properties and climate.

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Particle flux on the continental shelf in the Amundsen Sea Polynya and Western Antarctic Peninsula

Cited by 54 publications

References 76 publications

Seasonal sea ice changes in the Amundsen Sea, Antarctica, over the period of 1979–2014

Seasonal sea ice changes in the Amundsen Sea, Antarctica, over the period of 1979–2014

Sinking particle flux in the sea ice zone of the Amundsen Shelf, Antarctica

Dynamic Biological Functioning Important for Simulating and Stabilizing Ocean Biogeochemistry

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