MODIS direct broadcast data have been received and processed by the Space Science and Engineering Center (SSEC) at the University of Wisconsin-Madison since August 2000. The central location of SSEC on the North American continent allows reception of MODIS imagery in near real-time over the entire continental United States, the Gulf of Mexico, and much of Canada. All MODIS passes (day and night) above 5 degrees elevation are routinely acquired at SSEC by a SeaSpace TeraScan SX-EOS 4.4 meter autotracking antenna and ground station, and the raw data (Level-0) are archived on magnetic tape. Automatic processing to calibrated and geolocated radiance data (Level-1) and creation of quicklook images occurs routinely, and the latest 7 days of Level-1B data and quicklooks are made available online.

To help foster the widespread use of MODIS direct broadcast data, SSEC has been funded by NASA to develop freely available software for MODIS and AIRS Level-1 and Level-2 processing. The International MODIS/AIRS Processing Package (IMAPP) was first released in May 2000, and is now in use in more than 10 countries around the world. IMAPP currently implements Level-1 processing for Terra MODIS on a range of UNIX platforms, and during mid-2001, several MODIS product algorithms will be released as part of IMAPP, including a cloud mask, atmospheric temperature and moisture profiles, and cloud top pressure, temperature, and phase.

A new cloud classification algorithm has been developed for implementation with MODIS direct broadcast data. A maximum likelihood algorithm is used to classify surfaces into land, water, snow/ice, desert, vegetation, and also to classify different cloud types. This classification procedure refines the cloud mask algorithm, and enables further applications such as clear atmospheric profile or cloud parameter retrievals from the combination of MODIS and other sounder systems such as the Atmospheric Infrared Sounder (AIRS). The advantages of this method are the automated surface and cloud classification independent of radiance or brightness temperature threshold criteria, and interpretation of each class based on the radiative spectral characteristics of different classes.

This poster will describe the direct broadcast groundstation at SSEC, and the system used to produce near real-time Level-1B radiance data. Examples of geophysical products created from MODIS direct broadcast data will be presented.