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    • Chlorophyll-a Average Annual Frequency of Anomalies, 2002-2013 - Hawaii

    Metadata Updated: June 3, 2023

    Chlorophyll-a is a widely used proxy for phytoplankton biomass and an indicator for changes in phytoplankton production. As an essential source of energy in the marine environment, the extent and availability of phytoplankton biomass can be highly influential for fisheries production and dictate trophic structure in marine ecosystems. Changes in phytoplankton biomass are predominantly effected by changes in nutrient availability, through either natural (e.g., turbulent ocean mixing) or anthropogenic (e.g., agricultural runoff) processes. This layer represents the annual average number of anomalies of chlorophyll-a (mg/m3) from 2002-2013, with values presented as fraction of a year. Monthly and 8-day 4-km (0.0417-degree) spatial resolution data were obtained from the MODIS (Moderate-resolution Imaging Spectroradiometer) Aqua satellite instrument from the NASA OceanColor website (http://oceancolor.gsfc.nasa.gov).

    The chlorophyll-a average annual frequency of anomalies was calculated by taking the average number of times that the 8-day time series exceeded the maximum monthly climatological chlorophyll-a value from 2002-2013 for each pixel. A quality control mask was applied to remove spurious data associated with shallow water, following Gove et al., 2013. Monthly climatologies were calculated from monthly time series using only full years over the Ocean Tipping Points (OTP) project time frame of interest (2002-2013). 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.

    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 March 30, 2021
    Metadata Created Date November 12, 2020
    Metadata Updated Date June 3, 2023
    Reference Date(s) March 14, 2017 (creation), March 14, 2017 (issued), March 14, 2017 (revision)
    Frequency Of Update

    Metadata Source

    Harvested from ioos

    Other Data Resources

    Graphic Preview

    Sample image.

    Additional Metadata

    Resource Type Dataset
    Metadata Date March 30, 2021
    Metadata Created Date November 12, 2020
    Metadata Updated Date June 3, 2023
    Reference Date(s) March 14, 2017 (creation), March 14, 2017 (issued), March 14, 2017 (revision)
    Responsible Party National Center for Ecological Analysis and Synthesis (NCEAS) (Point of Contact)
    Contact Email
    Guid hi_otp_all_chlor_anom_freq
    Access Constraints
    Bbox East Long -154.56326617912035
    Bbox North Lat 22.42373568629166
    Bbox South Lat 18.755036208219373
    Bbox West Long -160.41246354980814
    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/hi_otp_all_chlor_anom_freq.png
    Harvest Object Id ffe66a2e-7516-455c-b78a-86428e3e4ec6
    Harvest Source Id 54e15a6e-6dde-4c9c-a8f0-345cc0dfccfb
    Harvest Source Title ioos
    Licence
    Lineage 2017-03-14T00:00:00Z 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": [[[-160.41246354980814, 18.755036208219373], [-154.56326617912035, 18.755036208219373], [-154.56326617912035, 22.42373568629166], [-160.41246354980814, 22.42373568629166], [-160.41246354980814, 18.755036208219373]]]}
    Progress
    Spatial Data Service Type Open Geospatial Consortium Web Coverage Service (WCS)
    Spatial Reference System
    Spatial Harvester True

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