Skip to main content
U.S. flag

An official website of the United States government

Official websites use .gov
A .gov website belongs to an official government organization in the United States.

Secure .gov websites use HTTPS
A lock ( ) or https:// means you’ve safely connected to the .gov website. Share sensitive information only on official, secure websites.

Skip to content

Turbidity (Kd490) Standard Deviation of Long-term Mean, 1998-2018 - American Samoa

Metadata Updated: October 6, 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 standard deviation of the 8-day time series 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 standard deviation was calculated over all 8-day Kd490 data 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. 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.

Downloads & Resources

Dates

Metadata Date September 7, 2021
Metadata Created Date October 6, 2023
Metadata Updated Date October 6, 2023
Reference Date(s) September 7, 2021 (creation), September 7, 2021 (issued), September 7, 2021 (revision)
Frequency Of Update

Metadata Source

Harvested from ioos

Graphic Preview

Sample image.

Additional Metadata

Resource Type Dataset
Metadata Date September 7, 2021
Metadata Created Date October 6, 2023
Metadata Updated Date October 6, 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_std
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_std.png
Harvest Object Id 169e2e14-ea58-430b-9310-e1db73d7a19a
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

Didn't find what you're looking for? Suggest a dataset here.