Onset conditions for equatorial spread F determined during EQUIS II

Dave L. Hysell, M. F. Larsen, Charles M. Swenson, Aroh Barjatya, T. F. Wheeler, M. F. Sarango, Ron F. Woodman, J. L. Chau

    Research output: Contribution to journalArticle

    34 Scopus citations

    Abstract

    An investigation into the dynamics and layer structure of the postsunset ionosphere prior to the onset of equatorial spread F (ESF) took place during the NASA EQUIS II campaign on Kwajalein Atoll on August 7 and 15, 2004. On both nights, an instrumented rocket measured plasma number density and vector electric fields to an apogee of about 450 km. Two chemical release rockets were launched both nights to measure lower thermospheric wind profiles. The Altair UHF/VHF radar was used to monitor coherent and incoherent scatter. In both experiments, strong plasma shear flow was detected. Periodic, patchy bottom-type scattering layers were observed in the westward-drifting plasma below the shear nodes. The large-scale plasma depletions that formed later during ESF reproduced the periodic structure of the original, precursor layers. The layers were therefore predictive of the ESF that followed. We surmise that collisional shear instabilities may have given rise to large-scale plasma waves that were highlighted by the bottom- type layer structure and that preconditioned the postsunset ionosphere for ESF.

    Original languageEnglish (US)
    Pages (from-to)1-4
    Number of pages4
    JournalGeophysical Research Letters
    Volume32
    Issue number24
    DOIs
    StatePublished - Dec 28 2005

    All Science Journal Classification (ASJC) codes

    • Geophysics
    • Earth and Planetary Sciences(all)

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