SuomiNet: A GPS Network for Real-time Atmospheric Sensing Invited Presentation to the IGS Network Workshop Oslo, Norway, July 12-14, 2000 Randolph Ware University Corporation for Atmospheric Research (UCAR) Boulder, Colorado 80307 USA ware@ucar.edu GPS networks are being established in a number of countries for atmospher= ic sensing. UCAR, in collaboration with participating universities, is de= veloping such a network. Named =93SuomiNet=94 to honor meteorological sat= ellite pioneer Verner Suomi, the project is funded by the U.S. National S= cience Foundation. UCAR will provide 100 GPS receivers to participating u= niversities. In turn, the universities will provide site equipment and In= ternet connection for five years. SuomiNet exploits the ability of ground= -based GPS receivers to make thousands of accurate upper and lower atmosp= heric measurements per day. Phase delays induced in GPS signals by the io= nosphere and neutral atmosphere can be measured with high precision simul= taneously along up to a dozen GPS ray paths in the field of view. These d= elays can be converted into total electron content (TEC), and integrated = water vapor (if surface or model pressure data are available), along each= GPS ray path. The resulting continuous, accurate, all-weather, real-time= upper and lower atmospheric data create a variety of opportunities for a= tmospheric research. SuomiNet, its applications, and the opportunity to c= oordinate national real-time GPS networks will be discussed. More informa= tion on SuomiNet is available via .=