Application of ground scatter returns for calibration of HF interferometry data

Abstract

Information on the vertical angle of arrival (elevation) is crucial in determining propagation modes of high-frequency (HF, 3-30 MHz) radio waves travelling through the ionosphere. The most advanced network of ionospheric HF radars, SuperDARN (Super Dual Auroral Radar Network), relies on interferometry to measure elevation, but this information is rarely used due to intrinsic difficulties with phase calibration as well as with the physical interpretation of the measured elevation patterns. In this work, we propose an empirical method of calibration for SuperDARN interferometry. The method utilises a well-defined dependence of elevation on range of ground scatter returns. "Fine tuning" of the phase is achieved based on a detailed analysis of phase fluctuation effects at very low elevation angles. The proposed technique has been successfully applied to data from the mid-latitude Hokkaido East SuperDARN radar. It can also be used at any other installation that utilises HF interferometry.

Diurnal and seasonal behavior of the Hokkaido East SuperDARN ground backscatter: simulation and observation

“…Our technique for identification of such echoes is very similar to that described in Bland et al (2014). Note that the elevation angle and range offset were previously calibrated for the Hokkaido East radar by Ponomarenko et al (2015). To distinguish regular GB echoes propagating in the E and F2 channels, we defined a mask including a set of criterion for the slant range, r full , and effective reflection height, h eff .…”

“…There was a distinct saturation effect in the observed elevation for moderate and high solar activity years. This can be explained by peculiarities of the antenna system such as (1) elevation angle aliasing effect at which the maximum measurable elevation is limited by 45° (Milan et al 1997;McDonald et al 2013;Ponomarenko et al 2015) and (2) partially by the narrow elevation radiation pattern (it affects the location of the power maximum that the procedure searches in each sounding session). However, the observed effective height on average agreed well with simulated one.…”

Statistical characteristics of medium-scale traveling ionospheric disturbances revealed from the Hokkaido East and Ekaterinburg HF radar data

“…Elevation angles are necessary for mapping the radar data and more accurate determination of the effective height where the HF waves are reflected. In case of the Hokkaido East radar, elevation angle measurements have been calibrated in 2014 (Ponomarenko et al 2015), and it allowed us to separate E and F region echoes.…”

“…The Ekaterinburg radar dataset has been processed from 2013 to 2014. As compared to our previous study, we have significantly improved a preprocessing algorithm for slant range variation extraction and mapping using calibrated elevation angles and range offset information for the Hokkaido East radar (Ponomarenko et al 2015). This allowed us to study the disturbances propagating in the E and F regions of the ionosphere separately.…”

Special issue “Coupling of the high and mid latitude ionosphere and its relation to geospace dynamics”

“…Ponomarenko et al (2015) have developed an algorithm for calibrating the elevation angle parameter of the SuperDARN radars, which is important in identifying echo locations. Furthermore, it is important to model the ionospheric parameters to extract the main characteristics of ionospheric disturbances.…”