ERDDAP

The Problems that ERDDAP Tries To Solve
Without ERDDAP, when a person (or a computer program) looks on the Internet for a specific type of scientific data (for example, oceanographic data like satellite sea surface temperature data), there are problems ...

• The datasets of interest are hard to find because they are at many different web sites.
• Each site requires a different protocol to request the data (for example, HTTP GET, XML, SOAP+XML, DAP, WCS, WFS, SOS, or an HTML form).
• Each site returns the data in a different format (for example, XML, SOAP+XML, DAP binary data stream, ASCII text, HDF 4, HDF 5, NetCDF, ...)
  and it isn't the common file format that you want (for example, .html table, ESRI .asc, Google Earth .kml, .mat, .nc, .csv, .tsv, .json, .xhtml, WMS).
• Data from different sites is hard to compare because the dates+times are expressed in different formats (for example, "Jan 2, 1985", "02-JAN-1985", "1/2/85", "2/1/85", "1985-01-02", or days since has Jan 1, 1980, or ...).

• ERDDAP aggregates data from diverse local and remote sources.
• ERDDAP offers several ways to search for datasets of interest (see options at right).
• ERDDAP lets you make requests in a standardized way, regardless of the data source's request protocol.
  • Gridded data is available via the DAP hyperslab protocol and WMS.
  • Tabular data is available via the DAP constraint protocol.
  ERDDAP also provides Data Access Forms (web pages) which help humans create the DAP requests. OPeNDAP's DAP is the recommended IOOS DMAC data transport mechanism and a NASA EOSDIS standard. (DAP is great!)
• ERDDAP lets you choose the file format for the results (for example, .html table, ESRI .asc, Google Earth .kml, .mat, .nc, .csv, .tsv, .json, .xhtml, .png).
• ERDDAP standardizes the dates+times in the results, either as:
  • UDUNITS-compatible "seconds since 1970-01-01T00:00:00Z" numbers, or
  • ISO 8601:2004 "extended" format strings (YYYY-MM-DDThh:mm:ssZ, for example, "1985-01-02T00:00:00Z").
  To avoid time zone and daylight savings confusion, time values are always converted to the UTC time zone.
• ERDDAP lets you request .png and .pdf image files with graphs and maps of the data, in addition to the raw data. Three special uses of these images are:
  • Web page authors can embed a graph with the latest data in a web page using an HTML <img> tag.
  • Anyone can use ERDDAP's 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.
  • Anyone can use or make Google Gadgets to display images with the latest data on their iGoogle home page.
• ERDDAP offers email/URL and RSS subscriptions, so you can be notified whenever a dataset changes.
• ERDDAP is a web application (for humans with browsers) and a web service (for computer programs). ERDDAP has REST- and ROA-style links to make ERDDAP's services available to computer programs, so that other web applications and web services can be built on top of ERDDAP.
• More Detailed Information

Get Started with ERDDAP:
Search for Datasets of Interest

• View a List of All Datasets

• Do a Full Text Search for Datasets

  

• Search for Datasets by Category

  Datasets can be categorized in different ways by the values of various metadata attributes.
  Click on an attribute (institution, ioos_category, long_name, standard_name) 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 by Protocol

  Protocols are the standards which define how to request data.
  Different protocols are appropriate for different types of data and for different client applications.
  Click on a protocol to see a list of datasets which are available via that protocol in ERDDAP.
   

  Protocol	Description
  griddap	griddap lets you use the DAP hyperslab protocol to request gridded data (for example, satellite data and climate model data) and graphs of gridded data.
  tabledap	tabledap lets you use the DAP constraint protocol to request tabular data (for example, buoy data) and graphs of tabular data.
  WMS	The Web Map Service (WMS) lets you request an image with data plotted on a map.