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Discovery of two distinct types of equatorial 150 km radar echoes
Author(s) -
Chau J. L.,
Kudeki E.
Publication year - 2013
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1002/grl.50893
Subject(s) - doppler effect , radar , equator , population , earth's magnetic field , geology , echo (communications protocol) , physics , incoherent scatter , spectral width , scattering , ionosphere , geophysics , geodesy , optics , magnetic field , latitude , astronomy , telecommunications , computer science , computer network , demography , quantum mechanics , wavelength , sociology
We show here that VHF signals scattered from the 150 km region above Jicamaca exhibit two distinct types of features. In one type (type A), the Doppler spectral width increases with the echo strength and the corresponding signal‐to‐noise ratio (SNR). A second type (type B) of higher SNR echoes exhibits SNR‐independent Doppler spectral widths that are much narrower than those observed in the first type. The type A echo population is by far the dominant population. Comparisons with earlier data sets collected at Jicamarca and elsewhere suggest that the type A and type B are likely to be associated with a naturally enhanced incoherent scattering (NEIS) process and the unstable growth of field‐aligned irregularities (FAIs), respectively. We conjecture that small radar systems operated near the geomagnetic equator that have reported 150 km echo observations detected FAI echoes and that the NEIS echoes can only be seen by high sensitivity systems.