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    • Turbidity (Kd490) Average Annual Maximum Anomaly, 1998-2018 - American Samoa

    Metadata Updated: October 7, 2023

    Spectrally resolved water-leaving radiances (ocean color) and inferred chlorophyll concentration are key to studying phytoplankton dynamics at seasonal and inter-annual scales, for a better understanding of the role of phytoplankton in marine biogeochemistry; the global carbon cycle; and the response of marine ecosystems to climate variability, change, and feedback processes. Ocean color data also have a critical role in operational observation systems monitoring coastal eutrophication, harmful algal blooms, and sediment plumes. The contiguous ocean color record reached 21 years in 2018. However, it is comprised of a number of one-off missions such that creating a consistent time series of ocean color data requires merging of the individual sensors without introducing artifacts.

    The diffuse attenuation coefficient at 490 nm (Kd490) indicates the turbidity of the water column: i.e., how well visible light in the blue to green region of the spectrum penetrates the water column. The value of Kd490 represents the rate at which light at 490 nm is attenuated with depth. For example, a Kd490 of 0.1 per meter means that light intensity is reduced by one natural log within 10 meters of water. Thus, for a Kd490 of 0.1, one attenuation length is 10 meters. Higher Kd490 values mean shallower attenuation depths and thus higher turbidity, or lower clarity, of ocean water. This layer represents the annual average of the maximum anomaly of Kd490 (m-1) from 1998-2018.

    Data products generated by the Ocean Colour component of the European Space Agency (ESA) Climate Change Initiative (CCI) project. These files are 8-day 4-km composites of merged sensor products: Global Area Coverage (GAC), Local Area Coverage (LAC), MEdium Resolution Imaging Spectrometer (MERIS), Moderate Resolution Imaging Spectroradiometer (MODIS) Aqua, Ocean and Land Colour Instrument (OLCI), Sea-viewing Wide Field-of-view Sensor (SeaWiFS), and Visible Infrared Imaging Radiometer Suite (VIIRS).

    The Kd490 average annual maximum anomaly was calculated by taking the average of the Kd490 values from the 8-day time series in exceedance of the maximum monthly climatological Kd490 from 1998-2018 for each pixel. A quality control mask was applied to remove spurious data associated with shallow water, following Gove et al., 2013. Time series of anomalies were calculated by quantifying the number and magnitude of events from the 8-day time series that exceed the maximum climatological monthly mean. Nearshore map pixels with no data were filled with values from the nearest neighboring valid offshore pixel by using a grid of points and the Near Analysis tool in ArcGIS then converting points to raster.

    Data source: https://oceanwatch.pifsc.noaa.gov/erddap/griddap/esa-cci-kd-8d-v5-0.graph

    Access & Use Information

    License: No license information was provided. If this work was prepared by an officer or employee of the United States government as part of that person's official duties it is considered a U.S. Government Work.

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    Dates

    Metadata Date September 7, 2021
    Metadata Created Date October 7, 2023
    Metadata Updated Date October 7, 2023
    Reference Date(s) September 7, 2021 (creation), September 7, 2021 (issued), September 7, 2021 (revision)
    Frequency Of Update

    Metadata Source

    Harvested from ioos

    Other Data Resources

    Graphic Preview

    Sample image.

    Additional Metadata

    Resource Type Dataset
    Metadata Date September 7, 2021
    Metadata Created Date October 7, 2023
    Metadata Updated Date October 7, 2023
    Reference Date(s) September 7, 2021 (creation), September 7, 2021 (issued), September 7, 2021 (revision)
    Responsible Party NOAA Pacific Islands Fisheries Science Center (PIFSC) (Point of Contact)
    Contact Email
    Guid as_noaa_all_turb_anom_max
    Access Constraints
    Bbox East Long -167.8250200967191
    Bbox North Lat -10.776491753888738
    Bbox South Lat -14.732036252835169
    Bbox West Long -171.33852794082935
    Coupled Resource [{"title": [], "href": ["#DataIdentification"], "uuid": []}, {"title": [], "href": ["#DataIdentification"], "uuid": []}, {"title": [], "href": ["#DataIdentification"], "uuid": []}]
    Frequency Of Update
    Graphic Preview Description Sample image.
    Graphic Preview File http://pacioos.org/metadata/browse/as_noaa_all_turb_anom_max.png
    Harvest Object Id 2fbf6466-1afe-4842-9600-46743f8f2dcd
    Harvest Source Id 54e15a6e-6dde-4c9c-a8f0-345cc0dfccfb
    Harvest Source Title ioos
    Licence
    Lineage 2021-09-07T00:00:00Z OGC web services (WMS and WFS) enabled by PacIOOS via GeoServer. Original data from source provider may have been reformatted, reprojected, or adjusted in other ways to optimize these capabilities.
    Metadata Language eng
    Metadata Type geospatial
    Old Spatial {"type": "Polygon", "coordinates": [[[-171.33852794082935, -14.732036252835169], [-167.8250200967191, -14.732036252835169], [-167.8250200967191, -10.776491753888738], [-171.33852794082935, -10.776491753888738], [-171.33852794082935, -14.732036252835169]]]}
    Progress
    Spatial Data Service Type Open Geospatial Consortium Web Coverage Service (WCS)
    Spatial Reference System
    Spatial Harvester True

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