What is Madrigal?

Madrigal is a robust, World Wide Web based system capable of managing and serving archival and real-time data, in a variety of formats, from a wide range of ground-based instruments. Madrigal is installed at a number of sites around the world. Each site controls their own Madrigal installation, and can add or upgrade their data from their instrument(s) on their site at any time. In addition to storing data in the standard Madrigal/Cedar format, each site can also add additional web-based documentation such as plots or descriptive notes to individual experiments they run.

However, Madrigal also defines standard metadata that all Madrigal sites share. This makes it possible for each Madrigal site to know about all the experiments on all the other sites. From a user's point of view, each Madrigal site allows them to search for data at all the Madrigal sites at once, and simply follow links to the Madrigal site that has the data they are interested in.

Madrigal was originally developed to serve the needs of the incoherent scatter radar community. There are Madrigal sites containing incoherent scatter radar data at Millstone Hill, USA, EISCAT, Sweden, Arecibo, Puerto Rico, SRI International, USA, Cornell University, USA, Jicamarca, Peru, The Institute of Solar-Terrestrial Physics, Russia, and Wuhan Ionospheric Observatory, the Chinese Academy of Sciences. In addition, many of these sites also store data from optical instruments on Madrigal, and the Millstone site holds total electron content data derived from the world-wide network of GPS receivers. Madrigal is designed to hold data from any ground-based instrument that studies atmospheric science.

Madrigal is often compared to the Cedar database. The Cedar database grew out of the existing Madrigal database in the late 1980's. The Cedar database is a central repository and archive for Cedar data, and shares the same data format as Madrigal. Since the Cedar database is a community resource, it guarantees data availability even when individual instruments and groups stop being active. The Madrigal database is focused on data that is being actively maintained by the groups that produced the data. Also, unlike the Cedar database, Madrigal organizes its data by experiments. This allows data to presented over the web in ways specifically suited to individual experiments. The organization of Madrigal data will be reviewed in the next section of this tutorial.

Madrigal also differs from the present Cedar database in that it has derivation engine built into it. This means that you can request many parameters that are not directly recorded in the data file, such as geophysical parameters, magnetic field parameters, model data, and alternative coordinate system parameters. In the web interface, the only difference between measured parameters and derived parameters will be that measured parameters are shown in bold font.

There are two ways to access Madrigal data - through a web browser, or through a programming language for which an application programming interface (API) has been written. This tutorial covers accessing Madrigal data via a web browser. There is also a tutorial covering accessing Madrigal data via API's.

Madrigal is an open source project with a central Web site . A complete CVS archive of all Madrigal software, including software which is not included with the standard distribution, is available there. There is also an Open Madrigal mailing list and developer's forum. Any group wishing to install Madrigal to distribute their instrument's data is welcome to - see the www.OpenMadrigal.org web site for details.