loading page

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:[email protected]

Author Profile
James LaBelle
Dartmouth College
Author Profile
Spencer Mark Hatch
Birkeland Centre for Space Science
Author Profile
Jøran I. Moen
Arctic Geophysics, University Centre in Svalbard, N-9171 Longyearbyen, Norway
Author Profile
Andres Spicher
University of Oslo
Author Profile
Toru Takahashi
National Institute of Polar Research
Author Profile
Craig A. Kletzing
University of Iowa
Author Profile
Scott Randolph Bounds
University of Iowa
Author Profile
Kjellmar Oksavik
University of Bergen
Author Profile
Fred Sigernes
University Centre on Svalbard
Author Profile
Tim Yeoman
University of Leicester, UK
Author Profile

Abstract

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