ERDDAP (the Environmental Research Division's Data Access Program)
is a web service that helps humans
and computer programs download
scientific data in common file formats and make graphs and maps.
This particular ERDDAP installation has oceanographic data
(for example, data from satellites and buoys).
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 ...).
You can Set Up Your Own ERDDAP Server
and serve your own data.
- ERDDAP is a web service that aggregates data from diverse remote sources
and offers a simple, consistent way to access the data.
- ERDDAP offers different 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.
ERDDAP also provides Data Access Forms (web pages) which help humans create the DAP requests.
is the recommended
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:
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
to display images with the latest data on their iGoogle home page.
- ERDDAP has REST- and ROA-style links to make its services available to
so that other web services can be built on top of ERDDAP.
- More Detailed Information
Get Started with ERDDAP:
ERDDAP offers a couple of ways to search for datasets:
Search for Datasets of Interest
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.
||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 lets you use the DAP constraint protocol to request tabular data (for example, buoy data) and graphs of tabular data.
||The Web Map Service (WMS) lets you request an image with data plotted on a map.