Make A Graph

Dataset Title:	Ekman Upwelling, METOP ASCAT, 0.25 degrees, Global, Near Real Time
Institution:	NOAA CoastWatch WCN (Dataset ID: erdQAwekm)
Information:	Summary \| License \| FGDC \| ISO 19115 \| Metadata \| Background \| Data Access Form

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Graph Type:
X Axis:
Y Axis:
Color:

Dimensions

Start

Stop

time (UTC)

specify just 1 value →

altitude (m)

specify just 1 value →

latitude (degrees_north)

longitude (degrees_east)

Graph Settings
Color Bar:	Continuity:	Scale:
Minimum:	Maximum:	N Sections:
Draw land mask:
Y Axis Minimum:	Maximum:

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

Optional:
Then set the File Type: (File Type information)
and

or view the URL:
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Click on the map to specify a new center point.

Zoom:

[The graph you specified. Please be patient.]

Things You Can Do With Your Graphs

Well, you can do anything you want with your graphs, of course. But some things you might not have considered are:

Web page authors can embed a graph of the latest data in a web page using HTML <img> tags.
Anyone can use ERDDAPs Slide Sorter to build a personal web page that displays graphs with the latest data (or other images or HTML content), each in its own, draggable slide.

The Dataset Attribute Structure (.das) for this Dataset

Attributes {
  time {
    String _CoordinateAxisType "Time";
    Float64 actual_range 1.4930352e+9, 1.6104528e+9;
    String axis "T";
    String calendar "gregorian";
    Int32 fraction_digits 0;
    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";
  }
  altitude {
    String _CoordinateAxisType "Height";
    String _CoordinateZisPositive "up";
    Float64 actual_range 0.0, 0.0;
    String axis "Z";
    Int32 fraction_digits 0;
    String ioos_category "Location";
    String long_name "Altitude";
    String positive "up";
    String standard_name "altitude";
    String units "m";
  }
  latitude {
    String _CoordinateAxisType "Lat";
    Float64 actual_range 30.0, 38.0;
    String axis "Y";
    String coordsys "geographic";
    Int32 fraction_digits 2;
    String ioos_category "Location";
    String long_name "Latitude";
    String point_spacing "even";
    String standard_name "latitude";
    String units "degrees_north";
  }
  longitude {
    String _CoordinateAxisType "Lon";
    Float64 actual_range 232.0, 243.0;
    String axis "X";
    String coordsys "geographic";
    Int32 fraction_digits 2;
    String ioos_category "Location";
    String long_name "Longitude";
    String point_spacing "even";
    String standard_name "longitude";
    String units "degrees_east";
  }
  QAwekm {
    Float32 _FillValue NaN;
    Float64 colorBarMaximum 2.0e-5;
    Float64 colorBarMinimum -2.0e-5;
    String coordinates "time altitude lat lon ";
    String coordsys "geographic";
    Int32 fraction_digits 6;
    String ioos_category "Currents";
    String long_name "Ekman Upwelling, METOP ASCAT, 0.25 degrees, Global, Near Real Time";
    Float32 missing_value NaN;
    Int32 numberOfObservations 343118;
    Float64 percentCoverage 0.3961914043330512;
    String units "m s-1";
  }
  NC_GLOBAL {
    String acknowledgement "NOAA NESDIS COASTWATCH, NOAA SWFSC ERD";
    String cdm_data_type "Grid";
    Int32 cols 1441;
    String composite "true";
    String contributor_name "EUMETSAT and NOAA|NESDIS";
    String contributor_role "Source of level 2 data.";
    String Conventions "CF-1.6, COARDS, Unidata Dataset Discovery v1.0";
    String creator_email "dave.foley@noaa.gov";
    String creator_name "NOAA CoastWatch, West Coast Node";
    String creator_url "https://coastwatch.pfeg.noaa.gov";
    String cwhdf_version "3.4";
    String date_created "2021-01-12";
    String date_issued "2021-01-12";
    Float64 Easternmost_Easting 243.0;
    Float64 et_affine 0.0, 0.25, 0.25, 0.0, 0.0, -75.0;
    Int32 gctp_datum 12;
    Float64 gctp_parm 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0;
    Int32 gctp_sys 0;
    Int32 gctp_zone 0;
    Float64 geospatial_lat_max 38.0;
    Float64 geospatial_lat_min 30.0;
    Float64 geospatial_lat_resolution 0.25;
    String geospatial_lat_units "degrees_north";
    Float64 geospatial_lon_max 243.0;
    Float64 geospatial_lon_min 232.0;
    Float64 geospatial_lon_resolution 0.25;
    String geospatial_lon_units "degrees_east";
    Float64 geospatial_vertical_max 0.0;
    Float64 geospatial_vertical_min 0.0;
    String geospatial_vertical_positive "up";
    String geospatial_vertical_units "m";
    String History 
"Translated to CF-1.0 Conventions by Netcdf-Java CDM (CFGridWriter2)
Original Dataset = satellite/QA/wekm/1day; Translation Date = 2021-01-13T22:17:22.927Z";
    String history 
"EUMETSAT and NOAA|NESDIS
2021-01-12T07:02:55Z NOAA CoastWatch (West Coast Node) and NOAA SFSC ERD
2025-04-26T06:02:38Z (local files)
2025-04-26T06:02:38Z https://odss.mbari.org/griddap/erdQAwekm.das";
    String id "LQAwekmS1day_20210111120000";
    String infoUrl "https://coastwatch.pfeg.noaa.gov";
    String institution "NOAA CoastWatch WCN";
    String keywords "ascat, circulation, coastwatch, degrees, downwelling, Earth Science > Oceans > Ocean Circulation > Upwelling/Downwelling, ekman, global, metop, near, near real time, noaa, ocean, oceans, quality, real, time, upwelling, wcn";
    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, CoastWatch, 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.";
    String Metadata_Conventions "CF-1.6, COARDS, Unidata Dataset Discovery v1.0";
    String naming_authority "gov.noaa.pfeg.coastwatch";
    Float64 Northernmost_Northing 38.0;
    String origin "EUMETSAT and NOAA|NESDIS";
    String original_institution "NOAA CoastWatch, West Coast Node";
    Int32 pass_date 18638;
    Float64 polygon_latitude -75.0, 75.0, 75.0, -75.0, -75.0;
    Float64 polygon_longitude 0.0, 0.0, 360.0, 360.0, 0.0;
    String processing_level "3";
    String project "CoastWatch (https://coastwatch.noaa.gov/)";
    String projection "geographic";
    String projection_type "mapped";
    String references "NOAA/NESDIS https://manati.orbit.nesdis.noaa.gov/products/ASCAT.php .";
    Int32 rows 601;
    String satellite "METOP";
    String sensor "ASCAT";
    String source "satellite observation: METOP, ASCAT";
    String sourceUrl "(local files)";
    Float64 Southernmost_Northing 30.0;
    String standard_name_vocabulary "CF-1.0";
    Float64 start_time 0.0;
    String summary "NOAA CoastWatch distributes near real time Ekman current (in zonal, meridional, and modulus sets) and Ekman upwelling data.  This data begins with wind velocity measurements from the ASCAT instrument onboard EUMETSAT's ASCAT satellite.  ASCAT is a microwave scatterometer designed to measure surface winds over the global ocean.  NOAA CoastWatch processes wind velocity to wind stress and wind stress curl, and finally to Ekman current and Ekman upwelling.";
    String time_coverage_end "2021-01-12T12:00:00Z";
    String time_coverage_start "2017-04-24T12:00:00Z";
    String title "Ekman Upwelling, METOP ASCAT, 0.25 degrees, Global, Near Real Time";
    Float64 Westernmost_Easting 232.0;
  }
}

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/jplMURSST.htmlTable?analysed_sst[(2015-06-09T09:00:00Z)][(-89.9945):1000:(89.9945)][(-179.995):1000:(179.995)]
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.