Ground based and satellite communication channel influences and Ultra Low Frequency (ULF) remote sensing techniques

We discuss the Lithosphere-Atmosphere-Ionosphere (LAI) coupling process occurring in the regions of strong seismic and volcanic activity leading to parameter changes in different altitudes of the atmosphere and ionosphere. Satellite - Earth and terrestrial ground based radio and optical links are affected by the LAI processes. Compared to typical (digital) communication systems we can interpret the measured parameter changes in the atmosphere and ionosphere as modification of the transmitting channel. Well known and experienced effects, such as scattering of Very Low Frequency (VLF) signals are interpreted as perturbations caused by LAI. On the example of a strong earthquake in the region of L´Aquila (Italy, M = 6.3) on April 6, 2009 we refer to ground based ULF observations and combine results to complementary VLF ground based measurements recorded in the local earthquake area. The approaches of VLF and ULF methods are complementary, but combined investigations improve the characterization of ionosphere perturbations. We conclude that ground based services from ULF measurements can detect variations of atmospheric parameters on local and global scales and can characterize the physical channel for satellite and navigation applications.