Data Access Form

Dataset Title:	SURF \| TPXO8 \| Tidal Elevation N2 1/30 Degree
Institution:	Oregon State University (Dataset ID: surf_osu_tpxo8_hf_n2_30_v1)
Information:	Summary \| License \| FGDC \| ISO 19115 \| Metadata \| Background \| Files \| Make a graph

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Dimensions	Size	Spacing
longitude (degrees_east)	10800	0.03333333 (even)

latitude (degrees_north)	5401	0.03333333 (even)

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

hRe (Tidal Elevation Complex Amplitude Real Part, mm)

hIm (Tidal Elevation Complex Amplitude Imaginary Part, mm)

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 {
  longitude {
    String _CoordinateAxisType "Lon";
    Float64 actual_range 0.033333334014147384, 359.999995931178;
    String axis "X";
    String ioos_category "Location";
    String long_name "Longitude";
    String standard_name "longitude";
    String units "degrees_east";
  }
  latitude {
    String _CoordinateAxisType "Lat";
    Float64 actual_range -90.0000035597249, 90.0000035597249;
    String axis "Y";
    String ioos_category "Location";
    String long_name "Latitude";
    String standard_name "latitude";
    String units "degrees_north";
  }
  hRe {
    String field "Re(z), scalar, amp=abs(hRe+i*hIm);GMT phase=atan2(-hIm,hRe)/pi*180;";
    String ioos_category "Sea Level";
    String long_name "Tidal Elevation Complex Amplitude Real Part";
    String option_0 "land";
    String option_1 "~=0 - water";
    String units "mm";
  }
  hIm {
    String field "Im(z), scalar";
    String ioos_category "Sea Level";
    String long_name "Tidal Elevation Complex Amplitude Imaginary Part";
    String option_0 "land";
    String option_1 "~=0 - water";
    String units "mm";
  }
  NC_GLOBAL {
    String cdm_data_type "Grid";
    String Conventions "COARDS, CF-1.10, ACDD-1.3";
    Float64 Easternmost_Easting 359.999995931178;
    Float64 geospatial_lat_max 90.0000035597249;
    Float64 geospatial_lat_min -90.0000035597249;
    Float64 geospatial_lat_resolution 0.033333334651749966;
    String geospatial_lat_units "degrees_north";
    Float64 geospatial_lon_max 359.999995931178;
    Float64 geospatial_lon_min 0.033333334014147384;
    Float64 geospatial_lon_resolution 0.03333333295649262;
    String geospatial_lon_units "degrees_east";
    String history 
"2026-06-06T01:10:11Z (local files)
2026-06-06T01:10:11Z https://erddap.cmcc-opa.eu/erddap/griddap/surf_osu_tpxo8_hf_n2_30_v1.das";
    String infoUrl "https://www.tpxo.net/";
    String institution "Oregon State University";
    String keywords "amplitude, elevation, imaginary, ocean, real, tidal, tide, water level";
    String license "Contact the data provider for redistribution and license terms.";
    Float64 Northernmost_Northing 90.0000035597249;
    String sourceUrl "(local files)";
    Float64 Southernmost_Northing -90.0000035597249;
    String summary "TPXO8 tidal elevation complex amplitude fields for constituent N2 at 1/30-degree resolution.";
    String title "SURF | TPXO8 | Tidal Elevation N2 1/30 Degree";
    String type "OTIS tidal elevation file";
    Float64 Westernmost_Easting 0.033333334014147384;
  }
}

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.