Triple-frequency meteor radar full wave scattering

Measurements and comparison to theory^★

¹ University of Bern & Oeschger Center for Climate Change Research, Microwave Physics, Bern, Switzerland
e-mail: gunter.stober@iap.unibe.ch
² University of Western Ontario, Department of Physics and Astronomy, London, Ontario, N6A 3K7, Canada
e-mail: pbrown@uwo.ca
³ Institute for Earth and Space Exploration, University of Western Ontario, London, Ontario, N6A 5B7, Canada
⁴ Institute for Astronomy, University of Hawaii, 2680 Woodlawn Drive, Honolulu, HI, 96822, USA
e-mail: weryk@hawaii.edu

Received: 3 June 2021
Accepted: 9 August 2021

Abstract

Context. Radar scattering from meteor trails depends on several poorly constrained quantities, such as electron line density, q, initial trail radius, r₀, and ambipolar diffusion coefficient, D.

Aims. The goal is to apply a numerical model of full wave backscatter to triple frequency echo measurements to validate theory and constrain estimates of electron radial distribution, initial trail radius, and the ambipolar diffusion coefficient.

Methods. A selection of 50 transversely polarized and 50 parallel polarized echoes with complete trajectory information were identified from simultaneous tri-frequency echoes recorded by the Canadian Meteor Orbit Radar. The amplitude-time profile of each echo was fit to our model using three different choices for the radial electron distribution assuming a Gaussian, parabolic-exponential, and 1-by-r² electron line density model. The observations were manually fit by varying, q, r₀, and D per model until all three synthetic echo-amplitude profiles at each frequency matched observation.

Results. The Gaussian radial electron distribution was the most successful at fitting echo power profiles, followed by the 1∕r². We were unable to fit any echoes using a profile where electron density varied from the trail axis as an exponential-parabolic distribution. While fewer than 5% of all examined echoes had self-consistent fits, the estimates of r₀ and D as a function of height obtained were broadly similar to earlier studies, though with considerable scatter. Most meteor echoes are found to not be described well by the idealized full wave scattering model.