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On the VHF radar echoes in the region of midnight aurora: Signs of ground echoes modulated by the ionosphere
Author(s) -
Kozlovsky Alexander,
Lester Mark
Publication year - 2015
Publication title -
journal of geophysical research: space physics
Language(s) - English
Resource type - Journals
eISSN - 2169-9402
pISSN - 2169-9380
DOI - 10.1002/2014ja020715
Subject(s) - ionosphere , substorm , physics , geophysics , meteor (satellite) , radar , over the horizon radar , amplitude , geology , doppler effect , radio wave , electrojet , sporadic e propagation , earth's magnetic field , optics , meteorology , magnetosphere , astronomy , plasma , telecommunications , computer science , quantum mechanics , magnetic field
We present all‐sky interferometric meteor radar (MR), VHF (36.9 MHz), observations from Sodankylä Geophysical Observatory and report on the unusual echoes, which were detected at low elevation on the northern horizon, typically during substorms. These echoes have a near‐zero Doppler shift, relatively low power, but with a sharp rise to the power peak, short lifetime (less than 2 s), and nonexponential decay (NED). We suggest that such auroral NED echoes are in fact ground backscatter of the MR waves which have been refracted in the ionosphere, passing through the ionosphere in the substorm region, where pulsating aurora (at a frequency higher than 1.7 Hz) occurs and causes quasiperiodic modulation of the wave propagation conditions, which leads to corresponding modulation of the amplitude of return. The MR treats such oscillating signal as meteor trails.