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Ann. Geophys., 23, 3419-3430, 2005
www.ann-geophys.net/23/3419/2005/
© European Geosciences Union 2005
Lightning driven inner radiation belt energy deposition into the atmosphere: regional and global estimates
C. J. Rodger1, M. A. Clilverd2, N. R. Thomson1, D. Nunn3, and J. Lichtenberger4
1Department of Physics, University of Otago, Dunedin, New Zealand
2Physical Sciences Division, British Antarctic Survey, Cambridge, UK
3School of Electronics and Computer Science, Southampton University, Southampton, UK
4Space Research Group, Eötvös University, Budapest, Hungary
Abstract. In this study we examine energetic electron precipitation
fluxes driven by lightning, in order to determine the global distribution of
energy deposited into the middle atmosphere. Previous studies using
lightning-driven precipitation burst rates have estimated losses from the
inner radiation belts. In order to confirm the reliability of those rates
and the validity of the conclusions drawn from those studies, we have
analyzed New Zealand data to test our global understanding of troposphere to
magnetosphere coupling. We examine about 10000h of AbsPAL recordings
made from 17 April 2003 through to 26 June 2004, and analyze subionospheric
very-low frequency (VLF) perturbations observed on transmissions from VLF
transmitters in Hawaii (NPM) and western Australia (NWC). These observations
are compared with those previously reported from the Antarctic Peninsula.
The perturbation rates observed in the New Zealand data are consistent with
those predicted from the global distribution of the lightning sources, once
the different experimental configurations are taken into account. Using
lightning current distributions rather than VLF perturbation observations we
revise previous estimates of typical precipitation bursts at L~2.3 to a
mean precipitation energy flux of ~1×10-3 ergs cm-2s-1.
The precipitation of energetic electrons
by these bursts in the range L=1.9-3.5 will lead to a mean rate of energy
deposited into the atmosphere of 3×10-4 ergs cm-2min-1, spatially varying from a low of zero
above some ocean regions to highs of ~3-6×10-3 ergs cm-2min-1 above North America and its conjugate
region.
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