Radar cross sections for mesospheric echoes at Jicamarca

G. A. Lehmacher, E. Kudeki, A. Akgiray, L. Guo, P. Reyes, J. Chau

Research output: Contribution to journalArticlepeer-review

Abstract

Radar cross sections (RCS) of mesospheric layers at 50MHz observed at Jicamarca, Peru, range from 10--18 to 10--16 m -1, three orders of magnitudes smaller than cross sections reported for polar mesospheric winter echoes during solar proton events and six orders of magnitude smaller than polar mesospheric summer echoes. Large RCS are found in thick layers around 70 km that also show wide radar spectra, which is interpreted as turbulent broadening. For typical atmospheric and ionospheric conditions, volume scattering RCS for stationary, homogeneous, isotropic turbulence at 3m are also in the range 10-18 to 10-16 m-1, in reasonable agreement with measurements. Moreover, theory predicts maximum cross sections around 70 km, also in agreement with observations. Theoretical values are still a matter of order-of-magnitude estimation, since the Bragg scale of 3m is near or inside the viscous subrange, where the form of the turbulence spectrum is not well known. In addition, steep electron density gradients can increase cross-sections significantly. For thin layers with large RCS and narrow spectra, isotropic turbulence theory fails and scattering or reflection from anisotropic irregularities may gain relevance.

Original languageEnglish (US)
Pages (from-to)2675-2684
Number of pages10
JournalAnnales Geophysicae
Volume27
Issue number7
DOIs
StatePublished - 2009

Keywords

  • Ionosphere (Equatorial ionosphere)
  • Meteorology and atmospheric dynamics (Turbulence)
  • Radio science (Atmospheric propagation)

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Geology
  • Atmospheric Science
  • Earth and Planetary Sciences (miscellaneous)
  • Space and Planetary Science

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