gov.noaa.ngdc.stp.ionosonde:3088User ServicesDOC/NOAA/NESDIS/NGDC > National Geophysical Data Center, NESDIS, NOAA, U.S. Department of Commerce20120101Ionograms are recorded tracings of reflected high frequency radio pulses generated by an ionosonde. Unique relationships exist between the sounding frequency and the ionization densities which can reflect it. As the sounder sweeps from lower to higher frequencies, the signal rises above the noise of commercial radio sources and records the return signal reflected from the different layers of the ionosphere.Ionospheric Research1920010120120101UnknownCompletenotPlanned-180.000000180.00000090.000000-90.000000NASA/GCMD Earth Science KeywordsSpace Physics, Ionosphere, Atmosphere, Indices, Communications, Remote SensingRestriction Code: otherRestrictions; Use Limitation: ; Other: Use Constraints: None; Other: Access Constraints: No Constraints; 20130429Justin MabieDOC/NOAA/NESDIS/NGDC > National Geophysical Data Center, NESDIS, NOAA, U.S. Department of Commercemailing and physical 325 Broadway, Mail Code E/GC4 BoulderCO80305-3328(303) 497-6135Justin.Mabie@noaa.govContent Standard for Digital Geospatial Metadata: Extensions for Remote Sensing MetadataFGDC-STD-012-2002