ONLINE ACCESS TO WEATHER-SATELLITE IMAGERY THROUGH THE WORLD-WIDE-WEB

Both global area coverage (GAC) and high-resolution picture transmissi on (HRPT) data from the Advanced Very High Resolution Radiometer (AVHR R) are made available to Internet users through an online data access system. Older GOES-7 data are also available, Created as a ''testbed'' data system for NASA's future Earth Observing System Data and Informa tion System (EOSDIS), this testbed provides an opportunity to test bot h the technical requirements of an online data system and the differen t ways in which the general user community would employ such a system, Initiated in December 1991, the basic data system experienced five ma jor evolutionary changes in response to user requests and requirements . Features added with these changes were the addition of online browse , user subsetting, dynamic image processing/navigation, a stand-alone data storage system, and movement from an X-windows graphical user int erface (GUI) to a World Wide Web (WWW) interface. Over its lifetime, t he system has had as many as 2500 registered users. The system on the WWW has had over 2500 hits since October 1995, Many of these hits are by casual users that only take the GIF images directly from the interf ace screens and do not specifically order digital data. Still, there i s a consistent stream of users ordering the navigated image data and r elated products (maps and so forth), We have recently added a real-tim e, seven-day, northwestern United States normalized difference vegetat ion index (NDVI) composite that has generated considerable interest.