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  • Oceanography  (3)
  • 577.1  (1)
  • ASFA_2015::E::Ecosystems  (1)
  • ASFA_2015::H::Human impact  (1)
  • Bottle, Niskin 10-L; Carbon, organic, particulate; Carbon, organic, total; Carbon, organic, total, standard deviation; DEPTH, water; NIS_10L; Nitrogen, organic, particulate; North Atlantic; Phosphorus, organic, particulate; POS284; POS284_171; Poseidon
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  • 1
    Publication Date: 2019-07-18
    Description: The intensive field observational phase of JGOFS in the North Atlantic Ocean has shown the importance of oceanic mesoscale variability on biogeochemical cycles and on the strength of the ocean biological pump. Mesoscale physical dynamics govern the major time/space scales of bulk biological variability (biomass, production and export). Mesoscale eddies seem to have a strong impact on the ecosystem structure and functioning, but observational evidence is rather limited. For the signature of the mesoscale features to exist in the ecosystem, the comparison of temporal scales of formation and evolution of mesoscale features and reaction of the ecosystem is a key factor. Biological patterns are driven by active changes in biological source and sink terms rather than simply by passive turbulent mixing. A first modelling assessment of the regional balances between horizontal and vertical eddy-induced nutrient supplies in the euphotic zone shows that the horizontal transport predominates over the vertical route in the subtropical gyre, whereas the reverse holds true for the other biogeochemical provinces of the North Atlantic. Presently. despite some difference in numbers, the net impact of modelled eddies yields an enhancement of the biological productivity in most provinces of the North Atlantic Ocean. Key issues remaining include variation on the mesoscale of subsurface particle and dissolved organic matter remineralization, improved knowledge of the ecological response to patterns of variability, synopticity in mesoscale surveys along with refining measures of biogeochemical time/space variability. Eventual success of assimilation of in situ and satellite data, still in its infancy in coupled physical/biogeochemical models, will be crucial to achieve JGOFS synthesis in answering which data are most informative, standing stocks or rates, and which ones are relevant. Depending on which end of the spectrum quantification of the effect of mesoscale features on production and community structure is required, complementary strategies are offered. Either one may choose to increase resolution of models up to the very fine mesoscale features scale (a few kms) for the high end, or to include a parametric representation of eddies for the low end.
    Keywords: Oceanography
    Type: Deep-Sea Research II; 48; 2199-2226
    Format: text
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  • 2
    Publication Date: 2019-07-18
    Description: The intensive field observational phase of JGOFS in the North Atlantic Ocean has shown the importance of oceanic mesoscale variability on biogeochemical cycles and on the strength of the ocean biological pump. Mesoscale physical dynamics govern the major time/space scales of bulk biological variability (biomass, production, and export). Mesoscale eddies seem to have a strong impact on the ecosystem structure and functioning, but observational evidence is rather limited. For the signature of the mesoscale features to exist in the ecosystem, the comparison of temporal scales of formation and evolution of mesoscale features and reaction of the ecosystem is a key factor. Biological patterns are driven by active changes in biological source and sink terms rather than simply by passive turbulent mixing. A first modelling assessment of the regional balances between horizontal and vertical eddy-induced nutrient supplies in the euphotic zone shows that the horizontal transport predominates over the vertical route in the subtropical gyre, whereas the reverse holds true for the other biogeochemical provinces of the North Atlantic. Presently, despite some difference in numbers, the net impact of modelled eddies yields an enhancement of the biological productivity in most provinces of the North Atlantic Ocean. Key issues remaining include variation on the mesoscale of subsurface particle and dissolved organic matter remineralization, improved knowledge of the ecological response to patterns of variability, synopticity in mesoscale surveys along with refining measures of biogeochemical time/space variability. Eventual success of assimilation of in situ and satellite data, still in its infancy in coupled physical/biogeochemical models, will be crucial to achieve JGOFS synthesis in answering which data are most informative, standing stocks or rates, and which ones are relevant. Depending on which end of the spectrum quantification of the effect of mesoscale features on production and community structure is required, complementary strategies are offered. Either one may choose to increase resolution of models up to the very fine mesoscale features scale (a few kms) for the high end, or to include a parametric representation of eddies for the low end.
    Keywords: Oceanography
    Type: Deep-Sea Research II (ISSN 0967-0645); 48; 2199-2226
    Format: text
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  • 3
    Publication Date: 2019-07-13
    Description: The ocean is responsible for up to a third of total global nitrous oxide (N2O) emissions, but uncertainties in emission rates of this potent greenhouse gas are high (approaching 100%). Here we use a marine biogeochemical model to assess six major uncertainties in estimates of N2O production, thereby providing guidance in how future studies may most effectively reduce uncertainties in current and future marine N2O emissions. Potential surface N2O production from nitrification causes the largest uncertainty in N2O emissions (estimated up to approximately 1.6 Tg N/yr (sup -1) or 48% of modeled values), followed by the unknown oxygen concentration at which N2O production switches to N2O consumption (0.8 Tg N/yr (sup -1)or 24% of modeled values). Other uncertainties are minor, cumulatively changing regional emissions by less than 15%. If production of N2O by surface nitrification could be ruled out in future studies, uncertainties in marine N2O emissions would be halved.
    Keywords: Oceanography
    Type: GSFC-E-DAA-TN15891 , Geophysical Research Letters; 41; 12; 4247–4253
    Format: application/pdf
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  • 4
    Publication Date: 2023-03-03
    Keywords: Bottle, Niskin 10-L; Carbon, organic, particulate; Carbon, organic, total; Carbon, organic, total, standard deviation; DEPTH, water; NIS_10L; Nitrogen, organic, particulate; North Atlantic; Phosphorus, organic, particulate; POS284; POS284_171; Poseidon
    Type: Dataset
    Format: text/tab-separated-values, 42 data points
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  • 5
    Publication Date: 2021-10-28
    Description: Gelatinous zooplankton (Cnidaria, Ctenophora, and Urochordata, namely, Thaliacea) are ubiquitous members of plankton communities linking primary production to higher trophic levels and the deep ocean by serving as food and transferring “jelly-carbon” (jelly-C) upon bloom collapse. Global biomass within the upper 200 m reaches 0.038 Pg C, which, with a 2–12 months life span, serves as the lower limit for annual jelly-C production. Using over 90,000 data points from 1934 to 2011 from the Jellyfish Database Initiative as an indication of global biomass (JeDI: http://jedi.nceas.ucsb.edu, http://www.bco-dmo.org/dataset/526852), upper ocean jelly-C biomass and production estimates, organism vertical migration, jelly-C sinking rates, and water column temperature profiles from GLODAPv2, we quantitatively estimate jelly-C transfer efficiency based on Longhurst Provinces. From the upper 200 m production estimate of 0.038 Pg C year−1, 59–72% reaches 500 m, 46–54% reaches 1,000 m, 43–48% reaches 2,000 m, 32–40% reaches 3,000 m, and 25–33% reaches 4,500 m. This translates into ~0.03, 0.02, 0.01, and 0.01 Pg C year−1, transferred down to 500, 1,000, 2,000, and 4,500 m, respectively. Jelly-C fluxes and transfer efficiencies can occasionally exceed phytodetrital-based sediment trap estimates in localized open ocean and continental shelves areas under large gelatinous blooms or jelly-C mass deposition events, but this remains ephemeral and transient in nature. This transfer of fast and permanently exported carbon reaching the ocean interior via jelly-C constitutes an important component of the global biological soft-tissue pump, and should be addressed in ocean biogeochemical models, in particular, at the local and regional scale.
    Keywords: 577.1 ; Jelly-C ; carbon ; gelatinous ; zooplankton ; modeling ; transfer efficiency
    Language: English
    Type: map
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  • 6
    Publication Date: 2022-09-15
    Description: Oxygen is critical to the health of the ocean. It structures aquatic ecosystems and is a fundamental requirement for marine life from the intertidal zone to the greatest depths of the ocean. Oxygen is declining in the ocean. Since the 1960s, the area of low oxygen water in the open ocean has increased by 4.5 million km2, and over 500 low oxygen sites have been identified in estuaries and other coastal water bodies. Human activities are a major cause of oxygen decline in both the open ocean and coastal waters. Burning of fossil fuels and discharges from agriculture and human waste, which result in climate change and increased nitrogen and phosphorus inputs, are the primary causes.
    Description: Published
    Description: Refereed
    Keywords: Global Ocean Oxygen Network ; GO2NE ; ASFA_2015::O::Oxygen ; ASFA_2015::D::Deoxygenation ; ASFA_2015::E::Ecosystems ; ASFA_2015::H::Human impact
    Repository Name: AquaDocs
    Type: Report
    Format: 40pp.
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