On the VHF radar echoes in the region of midnight aurora: Signs of ground echoes modulated by the ionosphere

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, relativel...

Full description

Saved in:
Bibliographic Details
Published in:Journal of geophysical research. Space physics 2015-03, Vol.120 (3), p.2099-2109
Main Authors: Kozlovsky, Alexander, Lester, Mark
Format: Article
Language:English
Subjects:
Auroras
Echoes
Geophysics
Grounds
Ionosphere
Meteor radar
Meteors
Meteors & meteorites
Modulation
Pulsating aurora
Radar
Radar ground scatter
VHF
Wave propagation
Citations: Items that this one cites
Items that cite this one
Online Access:Get full text
Tags: Add Tag
No Tags, Be the first to tag this record!
Description
Summary: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. Key Points Unusual meteor radar detections in auroral zone, never reported previously Signatures of pulsating (> 2 Hz) aurora in the ground scatter of the VHF radar The events are associated with substorms
ISSN:2169-9380
2169-9402
DOI:10.1002/2014JA020715