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GEOPHYSICAL RESEARCH LETTERS, VOL. 34, L11105, doi:10.1029/2007GL029881, 2007

Observed emission rates in sprite streamer heads

H. C. Stenbaek-Nielsen

Geophysical Institute, University of Alaska, Fairbanks, Alaska, USA

M. G. McHarg

Department of Physics, United States Air Force Academy, Colorado Springs, Colorado, USA

T. Kanmae

Geophysical Institute, University of Alaska, Fairbanks, Alaska, USA

D. D. Sentman

Geophysical Institute, University of Alaska, Fairbanks, Alaska, USA

Abstract

Sprite observations at 10,000 fps have shown tendrils and branches to be formed by bright streamer heads moving at ∼10⁷ m/s. The streamer heads typically brighten as they move up or down, often saturating the detector. We present here inferred emission rates. The streamer heads are presumably smaller than our 140 m spatial resolution and, therefore, they have to be treated as point sources. The optical emissions are assumed to be dominated by the N₂ 1P band and comparing with stars in the images we find total emission rates in individual streamer heads ranging from 4 10²¹ to 3 10²⁴ photons/s. For a 25 m streamer head the range of average brightness would be 9 10⁸–5 10¹¹ R. Alternatively, using a volume emission rate of 8 10¹¹ photons/cm³/s the size range would be 10 to 100 m.

Received 2 March 2007; accepted 1 May 2007; published 6 June 2007.

Keywords: sprites.

Index Terms: 3304 Atmospheric Processes: Atmospheric electricity; 3324 Atmospheric Processes: Lightning; 3332 Atmospheric Processes: Mesospheric dynamics; 3334 Atmospheric Processes: Middle atmosphere dynamics (0341, 0342); 3359 Atmospheric Processes: Radiative processes.

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Citation: Stenbaek-Nielsen, H. C., M. G. McHarg, T. Kanmae, and D. D. Sentman (2007), Observed emission rates in sprite streamer heads, Geophys. Res. Lett., 34, L11105, doi:10.1029/2007GL029881.

Copyright 2007 by the American Geophysical Union.