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The Cusp as a VLF Saucer Source: First Rocket Observations of Long-Duration VLF Saucers on the Dayside
  • +8
  • Chrystal Moser,
  • James LaBelle,
  • Spencer Mark Hatch,
  • Jøran I. Moen,
  • Andres Spicher,
  • Toru Takahashi,
  • Craig A. Kletzing,
  • Scott Randolph Bounds,
  • Kjellmar Oksavik,
  • Fred Sigernes,
  • Tim Yeoman
Chrystal Moser
Dartmouth College

Corresponding Author:chrystal.moser.gr@dartmouth.edu

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James LaBelle
Dartmouth College
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Spencer Mark Hatch
Birkeland Centre for Space Science
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Jøran I. Moen
Arctic Geophysics, University Centre in Svalbard, N-9171 Longyearbyen, Norway
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Andres Spicher
University of Oslo
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Toru Takahashi
National Institute of Polar Research
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Craig A. Kletzing
University of Iowa
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Scott Randolph Bounds
University of Iowa
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Kjellmar Oksavik
University of Bergen
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Fred Sigernes
University Centre on Svalbard
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Tim Yeoman
University of Leicester, UK
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Auroral whistler mode radio emissions called saucers are of fundamental interest because they require an unusually stationary emission process in the dynamic auroral environment, and it is a mystery how that can happen in this or similar conditions elsewhere in geospace. The Cusp Alfven and Plasma Electrodynamics Rocket (CAPER-2), launched into the polar cusp and obtained the first rocket measurements of a large-scale, multiple-armed dayside saucers, similar to those recently observed by the the DEMETER satellite, with the addition of in situ particle measurements and simultaneous conjugate ground-based measurements. For 300 s prior to cusp entry, CAPER-2 detected ~15 truncated saucer arms lasting 5–50 s. Directional analysis using waveforms, combined with ground-based data, suggests that these originate within the cusp. Ray-tracing analysis indicates source altitudes ~2500 km. On-board particle instruments show dispersed electron bursts in the cusp, presumed Alfvenically accelerated, corresponding to approximately the same source heights as the saucers.
28 Jan 2021Published in Geophysical Research Letters volume 48 issue 2. 10.1029/2020GL090747