2nd VERSIM Workshop 2006, Sodankylä, Finland, 26-30 September 2006

Atmospheric Precipitation during Storm-Time Relativistic Electron Flux drop outs

M. A. Clilverd1, C. J. Rodger2, R. M. Millan3, Th.Ulich4

1British Antarctic Survey (NERC), Cambridge, U.K.,
2Dept. of Physics, University of Otago, Dunedin, New Zealand,
3Dept of Physics and Astronomy, Dartmouth College, Hanover, NH, USA,
4Sodankylä Geophysical Observatory, Sodankylä, Finland.


During the sudden decrease of geosynchronous electron flux (>2 MeV) of 17:10-17:20 UT, January 21, 2005 large-scale precipitation into the atmosphere was observed by the VLF AARDDVARK network (the joint NZ/UK lead Antarctic-Arctic Radiation-belt (Dynamic) Deposition VLF Atmospheric Research Konsortium) and the MINIS balloon experiment. Estimates from ground-based radio propagation experiments at L~5 in the northern and southern hemispheres suggest that the atmospheric precipitation was less than 1/10 of the flux apparently lost during this 10 minute period. However, continuing precipitation losses from 4<L<6, observed for the next 2.7 hours, provides about 1/2 of the total relativistic electron content lost. Similarities and differences in the phenomena observed by MINIS and the AARDDVARK network during this event will be explored.