Make A Graph

Dataset Title:	NCEP Global Data Assimilation System GDAS, Daily, 1980-Present
Institution:	NOAA/OAR/ESRL Physical Sciences Laboratory (Dataset ID: ncep_gdas_global)
Information:	Summary \| License \| FGDC \| ISO 19115 \| Metadata \| Background \| Data Access Form \| Files

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.

Graph Type:
X Axis:
Y Axis:
Color:

Dimensions

Start

Stop

time (UTC)

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:
(Documentation / Bypass this form

)

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 3.155328e+8, 1.783728e+9;
    String axis "T";
    String delta_t "0000-00-01 00:00:00";
    String ioos_category "Time";
    String long_name "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";
    Float32 actual_range -90.0, 90.0;
    String axis "Y";
    String ioos_category "Location";
    String long_name "Latitude";
    String standard_name "latitude";
    String units "degrees_north";
  }
  longitude {
    String _CoordinateAxisType "Lon";
    Float32 actual_range 0.0, 357.5;
    String axis "X";
    String ioos_category "Location";
    String long_name "Longitude";
    String standard_name "longitude";
    String units "degrees_east";
  }
  sea_level_pressure {
    Float32 _FillValue 1530.32;
    Float64 colorBarMaximum 1050.0;
    Float64 colorBarMinimum 950.0;
    String comment "Data is from NMC initialized analysis (2x/day). It consists of most variables interpolated to the surface from model (sigma) surfaces.";
    String ioos_category "Pressure";
    String level_desc "Sea Level";
    String long_name "Sea Level Pressure";
    Float32 missing_value 1530.32;
    String parent_stat "Individual Obs";
    Int16 precision 2;
    String standard_name "air_pressure_at_mean_sea_level";
    String statistic "Mean";
    String units "mbar";
    Float32 valid_range 875.0, 1150.0;
    String var_desc "Sea level pressure";
  }
  windspeed_u {
    Float32 _FillValue 530.32;
    Float64 colorBarMaximum 15.0;
    Float64 colorBarMinimum -15.0;
    String comment "Data is from NMC initialized analysis (2x/day).  It consists of most variables interpolated to the surface from model (sigma) surfaces.";
    Float32 height 10.0;
    String height_units "m";
    String ioos_category "Wind";
    String level_desc "Surface";
    String long_name "Eastward Surface Wind Speed";
    Float32 missing_value 530.32;
    String parent_stat "Individual Obs";
    String standard_name "eastward_wind";
    String statistic "Mean";
    String units "m s-1";
    Float32 valid_range -125.0, 150.0;
    String var_desc "u-wind";
  }
  windspeed_v {
    Float32 _FillValue 530.32;
    Float64 colorBarMaximum 15.0;
    Float64 colorBarMinimum -15.0;
    String comment "Data is from NMC initialized analysis (2x/day).  It consists of most variables interpolated to the surface from model (sigma) surfaces.";
    Float32 height 10.0;
    String height_units "m";
    String ioos_category "Wind";
    String level_desc "Surface";
    String long_name "Northward Surface Wind Speed";
    Float32 missing_value 530.32;
    String parent_stat "Individual Obs";
    String standard_name "northward_wind";
    String statistic "Mean";
    String units "m s-1";
    Float32 valid_range -125.0, 150.0;
    String var_desc "v-wind";
  }
  air_temperature {
    Float32 _FillValue 805.32;
    Float64 colorBarMaximum 313.0;
    Float64 colorBarMinimum 263.0;
    String comment "Air Temperature";
    String ioos_category "Temperature";
    String level_desc "Surface";
    String long_name "Air Temperature";
    Float32 missing_value 805.32;
    String standard_name "air_temperature";
    String statistic "Mean";
    String units "K";
  }
  water_content {
    Float32 _FillValue 645.32;
    Float64 colorBarMaximum 75.0;
    Float64 colorBarMinimum 0.0;
    String comment "Entire Atmosphere Considered As a Single Layer";
    String ioos_category "Meteorology";
    String long_name "Precipitable Water Content";
    Float32 missing_value 645.32;
    String parent_stat "Individual Obs";
    String standard_name "atmosphere_mass_content_of_water_vapor";
    String statistic "Mean";
    String units "kg m-2";
    Float32 valid_range -10.0, 150.0;
    String var_desc "Precipitable Water Content";
  }
  relative_humidity {
    Float32 _FillValue 630.32;
    Float64 colorBarMaximum 100.0;
    Float64 colorBarMinimum 0.0;
    String ioos_category "Meteorology";
    String level_desc "Surface";
    String long_name "Relative Humidity";
    Float32 missing_value 630.31;
    String parent_stat "Individual Obs";
    String standard_name "relative_humidity";
    String statistic "Mean";
    String units "percent";
    Float32 valid_range -25.0, 125.0;
    String var_desc "Relative humidity";
  }
  station_pressure {
    Float32 _FillValue 9.96921e+36;
    Float64 colorBarMaximum 1050.0;
    Float64 colorBarMinimum 950.0;
    String comment "The actual, unadjusted atmospheric pressure measured at the station's real elevation";
    String ioos_category "Pressure";
    String level_desc "Surface";
    String long_name "Station / Surface Pressure";
    Float32 missing_value 9.96921e+36;
    String parent_stat "Individual Obs";
    String standard_name "surface_air_pressure";
    String statistic "Mean";
    String units "mbar";
    Float32 valid_range 400.0, 1100.0;
  }
  tropo_pressure {
    Float32 _FillValue 9.96921e+36;
    Float64 colorBarMaximum 500.0;
    Float64 colorBarMinimum 0.0;
    String ioos_category "Pressure";
    String level_desc "Tropopause";
    String long_name "Tropopause Air Pressure";
    Float32 missing_value 9.96921e+36;
    String parent_stat "Individual obs";
    String standard_name "tropopause_air_pressure";
    String statistic "Mean";
    String units "mbar";
    Float32 valid_range 10.0, 700.0;
    String var_desc "Tropopause Pressure";
  }
  NC_GLOBAL {
    String cdm_data_type "Grid";
    String Conventions "CF-1.10, COARDS, ACDD-1.3";
    String creator_email "psl.data@noaa.gov";
    String creator_name "NOAA PSL";
    String creator_type "institution";
    String creator_url "https://www.ncep.noaa.gov/";
    String dataset_title "NCEP Global Data Assimilation System GDAS";
    String delta_time "once daily";
    Float64 Easternmost_Easting 357.5;
    Float64 geospatial_lat_max 90.0;
    Float64 geospatial_lat_min -90.0;
    Float64 geospatial_lat_resolution 2.5;
    String geospatial_lat_units "degrees_north";
    Float64 geospatial_lon_max 357.5;
    Float64 geospatial_lon_min 0.0;
    Float64 geospatial_lon_resolution 2.5;
    String geospatial_lon_units "degrees_east";
    String history 
"/home/hoop/crdc/oldCRDC2COARDSv3/oldCRDC2COARDS Thu Dec 14 17:03:06 1995 from slp.82.nc
created 7/21/93 by C. Smith (netCDF2.3)
2026-07-13T01:08:21Z (local files)
2026-07-13T01:08:21Z https://coastwatch.pfeg.noaa.gov/griddap/ncep_gdas_global.das";
    String id "ncep_gdas_global";
    String infoUrl "https://www.psl.noaa.gov/data/gridded/data.ncep.html";
    String institution "NOAA/OAR/ESRL Physical Sciences Laboratory";
    String keywords "1980-present, air, air_pressure_at_mean_sea_level, air_temperature, altitude, assimilation, atmosphere, atmosphere_mass_content_of_water_vapor, atmospheric, boundary, centers, content, daily, data, day, earth, Earth Science > Atmosphere > Altitude > Tropopause, Earth Science > Atmosphere > Atmospheric Pressure > Atmospheric Pressure Measurements, Earth Science > Atmosphere > Atmospheric Pressure > Planetary Boundary Layer Height, Earth Science > Atmosphere > Atmospheric Pressure > Sea Level Pressure, Earth Science > Atmosphere > Atmospheric Pressure > Surface Pressure, Earth Science > Atmosphere > Atmospheric Temperature > Air Temperature, Earth Science > Atmosphere > Atmospheric Temperature > Surface Air Temperature, Earth Science > Atmosphere > Atmospheric Water Vapor > Humidity, Earth Science > Atmosphere > Atmospheric Water Vapor > Precipitable Water, Earth Science > Atmosphere > Atmospheric Water Vapor > Water Vapor, Earth Science > Atmosphere > Atmospheric Winds > Surface Winds, eastward, eastward_wind, environmental, esrl, gdas, global, height, humidity, laboratory, latitude, layer, level, longitude, mass, mean, measurements, meteorology, national, ncep, noaa, northward, northward_wind, oar, oceanic, office, physical, planetary, pr_wtr, precipitable, prediction, present, pressure, relative, relative_humidity, research, rhum, science, sciences, sea, seawater, slp, speed, srfp, station, surface, surface_air_pressure, system, temperature, time, tropopause, tropopause_air_pressure, trpp, twice, uwnd, vapor, vwnd, water, wind, winds";
    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.";
    String naming_authority "gov.noaa.pfeg.coastwatch";
    Float64 Northernmost_Northing 90.0;
    String platform "Model";
    String processing_level "Level 4";
    String producer "NCEP";
    String project "NCEP Global Data Assimilation System GDAS";
    String publisher_name "NOAA/NMFS/SWFSC";
    String publisher_type "institution";
    String publisher_url "https://coastwatch.pfeg.noaa.gov/";
    String references "https://www.psl.noaa.gov/data/gridded/data.ncep.html";
    String sourceUrl "(local files)";
    Float64 Southernmost_Northing -90.0;
    String standard_name_vocabulary "CF Standard Name Table v70";
    String summary "NCEP Global Data Assimilation System GDAS. Data is from National Centers for Environmental Prediction (NCEP) initialized analysis.  It consists of most variables interpolated to pressure surfaces from model (sigma) surfaces. Data is averged from 2x daily";
    String supplier "NCEP";
    String time_coverage_end "2026-07-11T00:00:00Z";
    String time_coverage_resolution "P1D";
    String time_coverage_start "1980-01-01T00:00:00Z";
    String title "NCEP Global Data Assimilation System GDAS, Daily, 1980-Present";
    Float64 Westernmost_Easting 0.0;
  }
}

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/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.