Ionospheric Data 2. Ionospheric Digital Database - 2 discs. The Ionospheric Digital Database compact discs contain approximately 40,000 station years (1.35 gigabytes) of scaled digital vertical incidence parameters from about 130 sites around the world for the period from 1957 through 1990.These data have been contributed through a major cooperative effort among the World Data Centers and many ionosonde network organizations. 32.Ionospheric Data - EL Arenosillo – 1974-1985, 1993-2003-2005- 3 discs 33.Ionospheric Data - EL Arenosillo – 1974-1985, 1993-2008; 2006, 2007- 3 discs