High Frequency (HF) radio propagation, and applications such as Over-The-Horizon Radar (OTHR), is sensitive to ionospheric disturbances caused by space weather. Improved ionospheric modelling and monitoring techniques for the high-latitude and polar regions supports high quality OTHR long-range surveillance. One such ionospheric disturbance is Sporadic-E, a phenomenon in which a thin enhancement in E-region (approximately 90–150 km altitude) electron density acts as a strong reflector of HF radio waves. In this study, we perform a case study of the effect a sporadic-E layer has on HF radio propagation for a layer that was detected over Eureka on July 11, 2012. We study this event using HF radio receiver measurements for a path intersecting the layer, simultaneous ionosonde measurements of the layer, and a series of ray traces through a model ionosphere containing a model of the sporadic-E layer. Utilizing these measurements and simulations, we show how sporadic-E can aid HF radio propagation in some cases, and show that a simple Gaussian sporadic-E model can replicate real HF radio measurements. We also comment on how sporadic-E could affect OTHR operation.
|Journal||Journal of Atmospheric and Solar-Terrestrial Physics|
|Early online date||13 Jan 2022|
|Publication status||Published - Feb 2022|
Bibliographical noteFunding Information:
This project was supported by TPA 02-2020 between the DRDC and NRC an under MoU 2018070005 between the DND and NRCan. HIPLAB was funded under the DRDC All Domain Situational Awareness (ADSA) program. NRCan HF transmitter network data for 2012 July 10?12 are available online at the Harvard Dataverse (https://doi.org/10.7910/DVN/YJMHKS). Infrastructure funding for CHAIN was provided by the Canada Foundation for Innovation (CFI) and the New Brunswick Innovation Foundation (NBIF). CHAIN and its operation are conducted in collaboration with the Canadian Space Agency (CSA). E-CHAIM is supported under Defence Research and Development Canada contract number W7714-186507/001/SS and is maintained by the Canadian High Arctic Ionospheric Network (CHAIN). This publication makes use of data from the Qaanaaq Digisonde, which was owned by the US Air Force Research Laboratory Space Vehicles Directorate and supported in part by the Air Force Office of Scientific Research. The authors thank Svend Erik Ascanius of the Danish Meteorological Institute and Denmark's Arctic Command for the operation of this ionosonde. The Leicester authors are grateful to the EPSRC for their support of the development of the modelling through grants EP/K008781/1, EP/C014642/1 and GR/N66056/01. This is NRCan publication number 20210241.
Over-the-horizon radar (OTHR), used for long-range surveillance ( Thayaparan et al., 2018 ; Cervera et al., 2018 ), relies on HF radio wave propagation, and is therefore sensitive to changes in the ionospheric electron density profile. Radio wave propagation modelling, or ray tracing, supports OTHR by predicting propagation paths to accurately range targets and optimize frequency selection ( Thayaparan et al., 2018 ; 2019a ; 2019b , 2020 ). This paper employs the High-Latitude Ionospheric Propagation Lab (HIPLAB) 3-D ray tracer toolbox to study the propagation of radio waves through the ionosphere. The University of Leicester developed HIPLAB with funding and support from Defence Research and Development Canada's (DRDC) All Domain Situational Awareness (ADSA) program ( Warrington, 2020 ). HIPLAB is based on Warrington et al. (2016) as described in Zaalov et al. (2003 , 2005) . This model builds on Jones and Stephenson (1975) by incorporating the Empirical Canadian High Arctic Ionospheric Model (E-CHAIM) ( Themens et al., 2017 , 2019 ), which is designed for high-latitude and Arctic (>50°) geomagnetic latitudes ( Thayaparan et al., 2020 ). This model operates by performing numerical ray traces through a modelled background ionosphere and then introduces perturbations to the background E and F region to represent the dynamic electron density structures frequently observed in these regions. Thayaparan et al. (2020) provide a description of the effects of polar cap patches in the F-region ionosphere on OTHR operating in the high-latitude and Arctic region. This paper provides a similar analysis on the effects on E-region electron density structures known as sporadic-E, or Es.
- High frequency radio wave propagation
ASJC Scopus subject areas
- Atmospheric Science
- Space and Planetary Science