An Overview of Unidata

Mission: To provide the data services, tools, and cyberinfrastructure leadership that advance Earth system science, enhance educational opportunities, and broaden participation.

Unidata, funded primarily by the National Science Foundation, is one of eight programs in the University Corporation for Atmospheric Research (UCAR) Office of Programs (UOP). UOP units create, conduct, and coordinate projects that strengthen education and research in the atmospheric, oceanic and earth sciences.

Unidata is a diverse community of over 160 institutions vested in the common goal of sharing data, and tools to access and visualize that data. For 20 years Unidata has been providing data, tools, and support to enhance Earth-system education and research. In an era of increasing data complexity, accessibility, and multidisciplinary integration, Unidata provides a rich set of services and tools.

The Unidata Program Center, as the leader of a broad community:

Under our current plans, we are:

Twenty of the 26 Unidata staff members have a technical background and most of them hold software engineering or system administrator positions. Six staff members have Ph.D.s in either a physical or computer science discipline.


The Unidata Program helps researchers and educators acquire and use earth-related data. Most of the data are provided in "real time" or "near-real time" -- that is, the data are sent to participants almost as soon as the observations are made. Unidata is a data facilitator, not a data archive center. We provide a mechanism whereby educators and researchers, by participating in our Internet Data Distribution (IDD) system, may subscribe to streams of current data that interest them.

Internet Data Distribution (IDD)

The Unidata community of over 160 universities is building a system for disseminating near real-time earth observations via the Internet. Unlike many other systems that are based on data centers, where the information can be accessed from a central location, the Unidata IDD is designed so a university can request that certain data sets be delivered to computers at their site as soon as they are available from the observing system. The IDD system also allows any site with access to specialized observations to inject the dataset into the IDD for delivery to other interested sites.

Types of data provided to the community in real-time by Unidata systems:

Data volume flowing to the community:


Unidata develops, maintains, and supports a variety of software packages. Most of these packages are developed at the Unidata Program Center (UPC), while a few others originated externally, but are modified, maintained, and supported at the UPC. Software provided by Unidata is available at no charge, but there are conditions on accessing or obtaining support for some packages. Unidata currently supports the following software.


NetCDF (network Common Data Form) is an interface for array-oriented data access and a library that provides an implementation of the interface. The netCDF library also defines a machine-independent format for representing scientific data. Together, the interface, library, and format support the creation, access, and sharing of scientific data.

Local Data Manager (LDM)

The Unidata Local Data Manager (LDM) is a collection of cooperating programs that select, capture, manage, and distribute arbitrary data products. The system is designed for event-driven data distribution, and is currently used in the Unidata Internet Data Distribution (IDD) project. The LDM system includes network client and server programs and their shared protocols. An important characteristic of the LDM is its support for flexible, site-specific configuration.


GEMPAK is an analysis, display, and product generation package for meteorological data. It is used at National Centers for producing operational forecast and analysis products. Graphical User Interfaces provide convenient access to interactive data manipulation. A comprehensive set of decoders enables integration of real-time and archive data, products, and bulletins.


The Man computer Interactive Data Access System (McIDAS) is a large, research quality suite of applications used for decoding, analyzing, and displaying meteorological data for research and education. The software can be used with conventional observational, satellite, and grid-point data.

Integrated Data Viewer (IDV)

The Integrated Data Viewer (IDV) from Unidata is a Java(TM)-based software framework for analyzing and visualizing geoscience data. The IDV brings together the ability to display and work with satellite imagery, gridded data, surface observations, balloon soundings, NWS WSR-88D Level II and Level III RADAR data, and NOAA National Profiler Network data, all within a unified interface.


Originally developed at the University of Rhode Island and MIT and supported by Unidata, OPeNDAP/DODS servers make remote scientific data accessible to data analysis and visualization packages that link to OPeNDAP/DODS client interfaces.


The Unidata units library, udunits, supports conversion of unit specifications between formatted and binary forms, arithmetic manipulation of unit specifications, and conver sion of values between compatible scales of measurement.


Software for cataloging, browsing, and accessing remote data and metadata through THREDDS (Thematic Realtime Environmental Distributed Data Services) catalogs. The THREDDS project is developing middleware to bridge the gap between data providers and data users. The goal is to simplify the discovery and use of scientific data and to allow scientific publications and educational materials to reference scientific data.

The mission of THREDDS is for students, educators and researchers to publish, contribute, find, and interact with data relating to the Earth system in a convenient, effective, and integrated fashion. Just as the World Wide Web and digital-library technologies have simplified the process of publishing and accessing multimedia documents, THREDDS is building infrastructure needed for publishing and accessing scientific data in a similarly convenient fashion.


The Unidata Program Center provides support to our diverse community, working in heterogeneous computing environments, on software, hardware, and related issues. Members can obtain support through the Unidata portal or via e-mail. We maintain discussion groups that allow community members to support each other, collaborate, and discuss important issues.

Three other mechanisms that help us serve our community are:


We also place strong emphasis on community-based governance. Unidata's governing committees facilitate consensus building for future directions for the program and establish standards of involvement for the community.

The Unidata Policy Committee holds the primary responsibility for guiding the Unidata Program. The Policy Committee, based on input from the Users Committee, makes recommendations to the UCAR President on our program’s policies, activities, and objectives. The second committee, the Users Committee, is the primary means for gaining feedback on our effectiveness in serving our members.