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Annales Geophysicae An interactive open-access journal of the European Geosciences Union
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Volume 22, issue 12
Ann. Geophys., 22, 4061–4069, 2004
https://doi.org/10.5194/angeo-22-4061-2004
© Author(s) 2004. This work is distributed under
the Creative Commons Attribution 3.0 License.
Ann. Geophys., 22, 4061–4069, 2004
https://doi.org/10.5194/angeo-22-4061-2004
© Author(s) 2004. This work is distributed under
the Creative Commons Attribution 3.0 License.

  22 Dec 2004

22 Dec 2004

Bottom-type scattering layers and equatorial spread F

D. L. Hysell1, J. Chun1, and J. L. Chau2 D. L. Hysell et al.
  • 1Department of Earth and Atmospheric Sciences, Cornell University, Ithaca, New York, USA
  • 2Radio Observatorio de Jicamarca, Instituto Geofísico del Perú, Lima, Peru

Abstract. Jicamarca radar observations of bottom-type coherent scattering layers in the post-sunset bottomside F-region ionosphere are presented and analyzed. The morphology of the primary waves seen in radar images of the layers supports the hypothesis of kudeki+bhattacharyya-1999 that wind-driven gradient drift instabilities are operating. In one layer event when topside spread F did not occur, irregularities were distributed uniformly in space throughout the layers. In another event when topside spread F did eventually occur, the irregularities within the pre-existing bottom-type layers were horizontally clustered, with clusters separated by about 30km. The same horizontal periodicity was evident in the radar plumes and large-scale irregularities that emerged later in the event. We surmise that horizontal periodicity in bottom-type layer irregularity distribution is indicative of large-scale horizontal waves in the bottomside F-region that may serve as seed waves for large-scale Rayleigh Taylor instabilities.

Key words. Ionosphere (equatorial ionosphere; ionospheric irregularties; plasma waves and instabilities)

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