Abstract
We studied regular diurnal and seasonal behaviors of ground backscatter propagation characteristics corresponding to the Hokkaido East Super Dual Auroral Radar Network (SuperDARN) (43.53° N, 143.61° E). Firstly, we simulated key propagation characteristics using a high frequency (HF) calculation technique based on the waveguide approach and International Reference Ionosphere (IRI)-2012 model as background ionosphere. The minimum slant range, skip distance, corresponding elevation angle, and true reflection height were considered in this study. The behaviors of these characteristics were well explained by diurnal and seasonal variations in the critical frequency and maximum height of corresponding ionosphere layer in HF reflection point. We estimated the accuracy of the standard SuperDARN mapping technique and proposed a means for its improvement. Secondly, we constructed an algorithm for mass data processing and extracted diurnal dependencies of the minimum slant range, corresponding elevation angle, and effective reflection height from the Hokkaido East SuperDARN dataset for a period from 2007 to 2014. The algorithm uses the simulated characteristics for distinguishing regular ground backscatter echoes propagating in the E and F2 HF channels. Observed monthly mean and simulated values of the characteristics were compared, and the result showed that the accuracy of IRI-2012 significantly depends on solar activity level and orientation of HF propagation path. In general, the difference between observed and simulated values decreased with increases in solar activity and azimuth. We also analyzed the occurrence of echoes originating behind the radar and found that they most frequently appear in winter and equinoxes before sunrise in beam #0 and after sunset in beam #15. The probability of their observation for a specific local time could reach up to 35 %.
Highlights
Super Dual Auroral Radar Network (SuperDARN; Chisham et al 2007) is currently the widest highfrequency (HF) (8–20 MHz) radar network that actively utilizes ground backscatter (GB) to study ionospheric processes
In this paper, we presented the results of GB simulation for an operating period of the 2007–2014 Hokkaido East SuperDARN
The simulation was performed using the original technique based on the waveguide approach and global ionosphere model International Reference Ionosphere (IRI)-2012
Summary
Super Dual Auroral Radar Network (SuperDARN; Chisham et al 2007) is currently the widest highfrequency (HF) (8–20 MHz) radar network that actively utilizes ground backscatter (GB) to study ionospheric processes. We simulated the diurnal and seasonal behaviors of key GB characteristics such as the minimum slant range, skip distance, corresponding elevation angle, and true height of HF reflection. To reduce the latter error while mapping, the use of the simulated slant range ratio might be effective (Fig. 2b) Another important task is the estimation of the critical frequency of the ionosphere. We extracted temporal variations of the minimum slant range, corresponding elevation angle, and effective reflection height (Eq (4)) of one-hop GB echoes. The bounds were selected on the basis of the above analysis, and they were empirically tested: 100 km < heff < 140 km and
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