ERDDAP

Easier Access to Scientific Data

Different scientific communities have developed different types of data servers.

For example, OPeNDAP, WCS, SOS, OBIS, and countless custom web pages with forms. Each is great on its own. But without ERDDAP, it is difficult to get data from different types of servers:

• Different data servers make you format your data request in different ways.
• Different data servers return data in different formats, usually not the common file format that you want.
• Different datasets use different formats for time data, so the results are hard to compare.

ERDDAP unifies the different types of data servers so you have a consistent way to get the data you want, in the format you want.

• ERDDAP acts as a middleman between you and various remote data servers. When you request data from ERDDAP, ERDDAP reformats the request into the format required by the remote server, sends the request to the remote server, gets the data, reformats the data into the format that you requested, and sends the data to you. You no longer have to go to different data servers to get data from different datasets.
   
• ERDDAP offers an easy-to-use, consistent way to request data: via the OPeNDAP standard. Many datasets can also be accessed via ERDDAP's Web Map Service (WMS).
   
• ERDDAP returns data in the common file format of your choice. ERDDAP offers all data as .html table, ESRI .asc and .csv, Google Earth .kml, OPeNDAP binary, .mat, .nc, ODV .txt, .csv, .tsv, .json, and .xhtml. So you no longer have to waste time and effort reformatting data.
   
• ERDDAP can also return a .png or .pdf image with a customized graph or map.
   
• ERDDAP standardizes the dates+times in the results. Data from other data servers is hard to compare because the dates+times often are expressed in different formats (for example, "Jan 2, 2018", 02-JAN-2018, 1/2/18, 2/1/18, 2018-01-02, "days since Jan 1, 1900"). For string times, ERDDAP always uses the ISO 8601:2004(E) standard format, for example, 2018-01-02T00:00:00Z. For numeric times, ERDDAP always uses "seconds since 1970-01-01T00:00:00Z". ERDDAP always uses the Zulu (UTC, GMT) time zone to remove the difficulties of working with different time zones and standard time versus daylight saving time. ERDDAP has a service to convert a string time to/from a numeric time.
   
• ERDDAP has web pages (for humans with browsers) and RESTful web services (for computer programs). You can bypass ERDDAP's web pages and use ERDDAP's RESTful web services (for example, for searching for datasets, for downloading data, for making maps) directly from any computer program (for example, Matlab, R, or a program that you write) and even from web pages (via HTML image tags or JavaScript). You can also build other useful and interesting things on top of ERDDAP's web services — see the Awesome ERDDAP list of awesome ERDDAP-related projects.

For a quick introduction to ERDDAP, watch the first half of this video. (5 minutes) In it, a scientist downloads ocean currents forecast data from ERDDAP to model a toxic spill in the ocean using NOAA's GNOME software (in 5 minutes!). Thanks to Rich Signell. (One tiny error in the video: when searching for datasets, don't use AND between search terms. It is implicit.)

Find out more about ERDDAP.

Data Providers: You can set up your own ERDDAP server and serve your own data. ERDDAP is free and open source. It uses Apache-like licenses, so you can do anything you want with it. ERDDAP's appearance is customizable, so your ERDDAP will reflect your institution, not NOAA. The small effort to set up ERDDAP brings many benefits. If you already have a web service for distributing your data, you can set up ERDDAP to access your data via the existing service or via the source files or database. Then, people will have another way to access your data and will be able to download the data in additional file formats or as graphs or maps. ERDDAP has been installed by over 60 organizations worldwide. NOAA's Data Access Procedural Directive includes ERDDAP in its list of recommended data servers for use by groups within NOAA.

Start Using ERDDAP:
    Search for Interesting Datasets

• Do a Full Text Search for Datasets

  Search

• View a List of All 241 Datasets

• Search for Datasets by Category

  Datasets can be categorized in different ways by the values of various metadata attributes. Click on an attribute (cdm_data_type, institution, ioos_category, keywords, long_name, standard_name, variableName) to see a list of categories (values) for that attribute. Then, you can click on a category to see a list of relevant datasets.

• Search for Datasets with Advanced Search 

• Search for Datasets by Protocol

  Protocols are the standards which specify how to request data. Different protocols are appropriate for different types of data and for different client applications.
   

  Protocol	Description
  griddap datasets	Griddap lets you use the OPeNDAP hyperslab protocol to request data subsets, graphs, and maps from gridded datasets (for example, satellite data and climate model data). griddap documentation
  tabledap datasets	Tabledap lets you use the OPeNDAP constraint/selection protocol to request data subsets, graphs, and maps from tabular datasets (for example, buoy data). tabledap documentation
  "files" datasets	ERDDAP's "files" system lets you browse a virtual file system and download source data files. WARNING! The dataset's metadata and variable names in these source files may be different than elsewhere in ERDDAP! You might prefer using the dataset's Data Access Form instead. "files" documentation
  WMS datasets	The Web Map Service (WMS) lets you request an image with data plotted on a map. WMS documentation

   

• Developers of computer programs and JavaScripted web pages can search for datasets via

  • ERDDAP's RESTful search services
  • ERDDAP's allDatasets tabular dataset that has a row of information for each dataset
  • ERDDAP's OpenSearch 1.1 Service

Converters
In addition to serving data, ERDDAP has some handy converters:

Metadata
ERDDAP has an
FGDC Web Accessible Folder (WAF) with FGDC‑STD‑001‑1998 metadata files and an
ISO 19115 Web Accessible Folder (WAF) with ISO 19115‑2/19139 metadata files for all of the geospatial datasets in this ERDDAP.

RESTful Web Services
You can bypass ERDDAP's web pages and use ERDDAP's RESTful web services (for example, for searching for datasets, for downloading data, for making maps) directly from any computer program (for example, Matlab, R, or a program that you write) and even from web pages (via HTML image tags or JavaScript). REST documentation

And