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  • Articles  (3)
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  • 1
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    The South Georgia island mass effect: observations from satellite imagery and biogeochemical modeling (2013)
    In:  EPIC3IUEM seminars, Laboratoire des sciences de l'environment marin, Plouzané, France, 2013-05-13
    Details
    Publication Date: 2019-07-16
    Description: Amidst high-nutrient low-chlorophyll waters of the south-western Atlantic sector of the Southern Ocean, an intense phytoplankton bloom is observed annually north of South Georgia (37°W, 55°S). South Georgia blooms have a vital role in the ecosystem surrounding the island, and have been linked to one of the strongest seasonal atmospheric-carbon uptake in the open Southern Ocean. Which environmental conditions drive such remarkable productivity are still under debate, and were investigated in the current study using a multidisciplinary approach. Satellite-derived observations of surface chlorophyll a concentrations and circulation patterns were used to study the annual and inter-annual variability of phytoplankton blooms in the region. Our analysis reveals a time series of very regular blooms, controlled in space by circulation and regulated in time by surface silicate concentrations, temperature and light. The role of the fundamental, yet limiting, micronutrient iron was investigated with the coupled hydrodynamic-biogeochemical model ROMS_AGRIF-PISCES. Model results, validated against available observations, suggest a continuous supply of dissolved iron from the island's shallow shelves that is redistributed in the region by local circulation. Conversely, aeolian sources of iron have a negligible role in the main bloom area, but appear to be more important outside the influence of the South Georgia island mass effect.
    Repository Name: EPIC Alfred Wegener Institut
    Type: Conference , notRev
    Location Call Number Limitation Availability
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  • 2
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    Sedimentary and atmospheric sources of iron around South Georgia, Southern Ocean: a modelling perspective (2014)
    COPERNICUS GESELLSCHAFT MBH
    In:  EPIC3Biogeosciences, COPERNICUS GESELLSCHAFT MBH, 11, pp. 1981-2001, ISSN: 1726-4170
    Details
    Publication Date: 2014-04-22
    Description: In high-nutrient low-chlorophyll waters of the western Atlantic sector of the Southern Ocean, an intense phytoplankton bloom is observed annually north of South Georgia. Multiple sources, including shallow sediments and atmospheric dust deposition, are thought to introduce iron to the region. However, the relative importance of each source is still unclear, owing in part to the scarcity of dissolved iron (dFe) measurements in the South Georgia region. In this study, we combine results from a recently published dFe data set around South Georgia with a coupled regional hydrodynamic and biogeochemical model to further investigate iron supply around the island. The biogeochemical component of the model includes an iron cycle, where sediments and dust deposition are the sources of iron to the ocean. The model captures the characteristic flow patterns around South Georgia, hence simulating a large phytoplankton bloom to the north (i.e. downstream) of the island. Modelled dFe concentrations agree well with observations (mean difference and root mean square errors of ~0.02 nM and ~0.81 nM) and form a large plume to the north of the island that extends eastwards for more than 800 km. In agreement with observations, highest dFe concentrations are located along the coast and decrease with distance from the island. Sensitivity tests indicate that most of the iron measured in the main bloom area originates from the coast and very shallow shelf-sediments (depths 〈 20 m). Dust deposition exerts almost no effect on surface chlorophyll a concentrations. Other sources of iron such as run-off and glacial melt are not represented explicitly in the model, however we discuss their role in the local iron budget.
    Repository Name: EPIC Alfred Wegener Institut
    Type: Article , isiRev , info:eu-repo/semantics/article
    Format: application/pdf
    Location Call Number Limitation Availability
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    PAPER (OA)
  • 3
    facet.materialart.
    Unknown
    Sedimentary and atmospheric sources of iron around South Georgia, Southern Ocean: a modelling perspective (2014)
    COPERNICUS GESELLSCHAFT MBH
    In:  EPIC3Biogeosciences, COPERNICUS GESELLSCHAFT MBH, 11(7), pp. 1981-2001, ISSN: 1726-4170
    Details
    Publication Date: 2014-04-14
    Description: In high-nutrient low-chlorophyll waters of the western Atlantic sector of the Southern Ocean, an intense phytoplankton bloom is observed annually north of South Georgia. Multiple sources, including shallow sediments and atmospheric dust deposition, are thought to introduce iron to the region. However, the relative importance of each source is still unclear, owing in part to the scarcity of dissolved iron (dFe) measurements in the South Georgia region. In this study, we combine results from a recently published dFe data set around South Georgia with a coupled regional hydrodynamic and biogeochemical model to further investigate iron supply around the island. The biogeochemical component of the model includes an iron cycle, where sediments and dust deposition are the sources of iron to the ocean. The model captures the characteristic flow patterns around South Georgia, hence simulating a large phytoplankton bloom to the north (i.e. downstream) of the island. Modelled dFe concentrations agree well with observations (mean difference and root mean square errors of �0.02nM and �0.81 nM) and form a large plume to the north of the island that extends eastwards for more than 800 km. In agreement with observations, highest dFe concentrations are located along the coast and decrease with distance from the island. Sensitivity tests indicate that most of the iron measured in the main bloom area originates from the coast and very shallow shelf-sediments (depths 〈 20 m). Dust deposition exerts almost no effect on surface chlorophyll a concentrations. Other sources of iron such as run-off and glacial melt are not represented explicitly in the model, however we discuss their role in the local iron budget.
    Repository Name: EPIC Alfred Wegener Institut
    Type: Article , isiRev , info:eu-repo/semantics/article
    Format: application/pdf
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
    PAPER (OA)
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