Data Access Form

Dataset Title:	X-Experimental Chlorophyll, S-NPP VIIR, Alaska, Daily
Institution:	NOAA NESDIS STAR (Dataset ID: jpss_chl_alaska)
Information:	Summary \| License \| FGDC \| ISO 19115 \| Metadata \| Background \| Files \| Make a graph

To work correctly, this web page requires that JavaScript be enabled in your browser. Please:
1) Enable JavaScript in your browser:
      • Chrome: "Settings : Advanced : Privacy and security : Site Settings : JavaScript"
      • Firefox: (it should be always on!)"
      • Opera: "Settings : Websites : JavaScript"
      • Safari: "Safari : Preferences : Security : Enable JavaScript"
2) Reload this web page.

Dimensions	Size	Spacing
time (Centered Time, UTC)	3784	1 day 0h 1m 53s (uneven)

latitude (degrees_north)	2667	-0.0075 (even)

longitude (degrees_east)	4667	0.0075 (even)

Grid Variables (which always also download all of the dimension variables)

chlor_a (Chlorophyll Concentration, OC3 Algorithm, mg m^-3)

File type: (more information)

(Documentation / Bypass this form)

(Please be patient. It may take a while to get the data.)

The Dataset Attribute Structure (.das) for this Dataset

Attributes {
  time {
    String _CoordinateAxisType "Time";
    Float64 actual_range 1.3255344e+9, 1.652814e+9;
    String axis "T";
    String calendar "gregorian";
    String ioos_category "Time";
    String long_name "Centered Time";
    String standard_name "time";
    String time_origin "01-JAN-1970 00:00:00";
    String units "seconds since 1970-01-01T00:00:00Z";
  }
  latitude {
    String _CoordinateAxisType "Lat";
    Float64 actual_range 54.00375, 73.99875;
    String axis "Y";
    String ioos_category "Location";
    String long_name "Latitude";
    String standard_name "latitude";
    String units "degrees_north";
  }
  longitude {
    String _CoordinateAxisType "Lon";
    Float64 actual_range 175.00125, 209.99625;
    String axis "X";
    String ioos_category "Location";
    String long_name "Longitude";
    String standard_name "longitude";
    String units "degrees_east";
  }
  chlor_a {
    Float32 _FillValue -999.0;
    Float64 colorBarMaximum 30.0;
    Float64 colorBarMinimum 0.03;
    String colorBarScale "Log";
    String ioos_category "Ocean Color";
    String long_name "Chlorophyll Concentration, OC3 Algorithm";
    Float32 missing_value -999.0;
    String standard_name "mass_concentration_of_chlorophyll_in_sea_water";
    String units "mg m^-3";
  }
  NC_GLOBAL {
    String cdm_data_type "Grid";
    String Conventions "CF-1.6, COARDS, ACDD-1.3";
    String creator_email "coastwatch.info@noaa.gov";
    String creator_name "NOAA/NESDIS/STAR/CoastWatch/WestCoast";
    String creator_type "institution";
    String creator_url "http://www.star.nesdis.noaa.gov/socd/mecb/color/";
    Float64 Easternmost_Easting 209.99625;
    Float64 geospatial_lat_max 73.99875;
    Float64 geospatial_lat_min 54.00375;
    Float64 geospatial_lat_resolution 0.0075000000000000015;
    String geospatial_lat_units "degrees_north";
    Float64 geospatial_lon_max 209.99625;
    Float64 geospatial_lon_min 175.00125;
    Float64 geospatial_lon_resolution 0.007500000000000001;
    String geospatial_lon_units "degrees_east";
    String grid_mapping__CoordinateAxisTypes "GeoX GeoY";
    String grid_mapping__CoordinateTransformType "Projection";
    Float64 grid_mapping_inverse_flattening 298.257223563;
    Float64 grid_mapping_longitude_of_prime_meridian 0.0;
    String grid_mapping_name "latitude_longitude";
    Float64 grid_mapping_semi_major_axis 6378137.0;
    String history 
"Spacial bin of CoastWatch high resolution sectors
2024-04-16T21:01:58Z (local files)
2024-04-16T21:01:58Z https://polarwatch.noaa.gov/erddap/griddap/jpss_chl_alaska.das";
    String infoUrl "http://www.star.nesdis.noaa.gov/socd/mecb/color/";
    String institution "NOAA NESDIS STAR";
    String instrument "VIIRS";
    String keywords "alaska, algorithm, available, chemistry, chla, chlor_a, chlorophyll, chlorophyll-a, coefficients, color, color/ocean, concentration, daily, data, day, earth, Earth Science > Oceans > Ocean Chemistry > Chlorophyll, Earth Science > Oceans > Ocean Optics > Ocean Color/Ocean Turbidity/Water-Leaving Radiance/Extinction Coefficients, environmental, extinction, information, latitude, leaving, longitude, mass, mass_concentration_of_chlorophyll_in_sea_water, national, nesdis, noaa, npp, oc3, ocean, ocean color, oceans, optics, orbiting, par, partnership, photosynthetically, polar, polar-orbiting, radiance, radiance/extinction, radiation, s-npp, satellite, science, sea, seawater, service, star, time, turbidity, turbidity/water-leaving, viir, water";
    String keywords_vocabulary "GCMD Science Keywords";
    String license 
"The data may be used and redistributed for free but is not intended
for legal use, since it may contain inaccuracies. Neither the data
Contributor, ERD, NOAA, nor the United States Government, nor any
of their employees or contractors, makes any warranty, express or
implied, including warranties of merchantability and fitness for a
particular purpose, or assumes any legal liability for the accuracy,
completeness, or usefulness, of this information.";
    Float64 Northernmost_Northing 73.99875;
    String platform "S-NPP";
    String publisher_email "coastwatch.info@noaa.gov";
    String publisher_name "NOAA CoastWatch West Coast, NOAA/NMFS/SWFSC/ERD)";
    String publisher_type "institution";
    String publisher_url "https://coastwatch.noaa.gov; https://www.ncei.noaa.gov/";
    String satellite "S-NPP";
    String sensor "VIIRS";
    String source "S-NPP_VIIRS_chlora";
    String sourceUrl "(local files)";
    Float64 Southernmost_Northing 54.00375;
    String standard_name_vocabulary "CF Standard Name Table v70";
    String summary "Ocean color standard products include normalized water-leaving radiances, chlorophyll-a concentration, diffusive attenuation coefficient at 490 nm and diffusive attenuation coefficient of the photosynthetically available radiation (PAR).";
    String time_coverage_end "2022-05-17T19:00:00Z";
    String time_coverage_start "2012-01-02T20:00:00Z";
    String title "X-Experimental Chlorophyll, S-NPP VIIR, Alaska, Daily";
    Float64 Westernmost_Easting 175.00125;
  }
}

Using griddap to Request Data and Graphs from Gridded Datasets

griddap lets you request a data subset, graph, or map from a gridded dataset (for example, sea surface temperature data from a satellite), via a specially formed URL. griddap uses the OPeNDAP (external link)

Data Access Protocol (DAP) (external link)

and its projection constraints (external link)

The URL specifies what you want: the dataset, a description of the graph or the subset of the data, and the file type for the response.

(easy) You can get data by using the dataset's Data Access Form. It makes the URL for you.
(easy) You can make a graph or map by using the dataset's Make A Graph form. It makes the URL for you.
(not hard) You can bypass the forms and get the data or make a graph or map by generating the URL by hand or with a computer program or script.

griddap request URLs must be in the form
https://coastwatch.pfeg.noaa.gov/erddap/griddap/datasetID.fileType{?query}
For example,
https://coastwatch.pfeg.noaa.gov/erddap/griddap/jplMURSST41.htmlTable?analysed_sst[(2002-06-01T09:00:00Z)][(-89.99):1000:(89.99)][(-179.99):1000:(180.0)]
Thus, the query is often a data variable name (e.g., analysed_sst), followed by [(start):stride:(stop)] (or a shorter variation of that) for each of the variable's dimensions (for example, [time][latitude][longitude]).

For details, see the griddap Documentation.