Detection of Magnetospherically Ducted VLF Signals Geomagnetically Conjugate to a Russian Alpha Transmitter at L=1.9
Morris Cohen1, Mark Golkowski2, Nikolai G. Lehtinen1, Umran S. Inan1,3, Michel Parrot4
1. Electrical Engineering, Stanford University, Stanford, CA, USA, 2. Electrical Engineering, University of Colorado Denver, Denver, CO, USA, 3. Electrical Engineering, Koc University, Istanbul, Turkey, 4. LPC2E, CNRS, Orleans, France

The Russian 'Alpha' transmitters broadcast alternating pulses between 11-15 kHz for navigation. A fraction of the VLF energy escapes into the magnetosphere, is guided by ducts, amplified by interaction with radiation belt particles, and observed at the geomagnetic conjugate point. We analyze VLF data from Adelaide, Australia, conjugate to the Komsomolsk transmitter. An automated detection scheme separates the subionospheric and magnetospheric signals. We track availability of ducts at L=1.9 and find them present often. We connect the ground signal to the signal observed by the DEMETER spacecraft, which also observe triggered emissions and spectral broadening. We correlate to geomagnetic conditions to assess the role of wave growth and triggering from wave-particle interactions. We also find a strong diurnal variation in the magnetospheric signal, and apply a full-wave model of transionospheric propagation to include the effects of ionospheric absorption on both ends.