Study of measured and predicted reliability of the ionospheric HF communication channel at high latitudes

Abstract

This paper describes observations of the reliability of the ionospheric HF communication channel within and close to the northern auroral zone. Automatic equipment has been developed to measure reliability and virtual reflection height as a function of frequency in an hourly cycle. Measurements have been made over two propagation paths within Norway. The data show diurnal and seasonal variations as well as dependence of the measured parameters on geomagnetic conditions. The observations have been compared with predictions obtained from the Ionospheric Communication Enhanced Profile Analysis and Circuit Prediction Program (ICEPAC) prediction code. This code includes a model of the high‐latitude and polar ionospheres and their dependence upon geomagnetic disturbances. The results of the comparison show that ICEPAC represents an improvement over previous codes but that transmission losses are not properly included.

Comparison of observed and predicted MUF(3000)F2 in the polar cap region

“…All models roughly reproduce the general diurnal trend observed in the measurements during the winter and equinox periods. This observation is consistent with the results of Thrane et al [] in their comparison of measured and modeled reliability and MUF at high latitudes. Both predictions and observations show diurnal and seasonal variations; however, the models do not reproduce the actual hourly variability observed in the measurements.…”

“…In Figure a, ICEPAC and VOACAP systematically overestimate the MUF(3000)F2 throughout all the hours, while REC533 gives values close to observations except from 07:00–08:00 UT and 19:00–24:00 UT where small divergences occur. Overestimation in VOACAP and ICEPAC MUF predictions have been observed at high latitudes [e.g., Thrane et al , ; Goodman and Ballard , ]. Thrane et al [] observed a tendency of VOACAP and ICEPAC predictions to overestimate MUF up to a factor of 2 at noon time.…”

“…Long‐term models depend on the reliability and accuracy of ionospheric models: VOACAP uses an ionospheric model based on the parabolic layer theory, while ICEPAC uses Chapman layers for the F1, and F2 layers as well as coefficients approved by URSI [ Bilitza , ]. ICEPAC contains the ionospheric conductivity and electron density (ICED) profile model, a statistical model that takes into account the different physical processes of the large‐scale features of the Northern Hemisphere ionosphere [ Tascione et al , ; Thrane et al , ; Stewart and Hand , ]. REC533 uses the NeQuick ionospheric model, referred to as version 1 or ITU‐R, which was accepted by ITU‐R sector in the early 2000s [ Leitinger et al , ; Bidaine et al , ; International Telecommunication Union , ].…”

“…Various studies have been undertaken to account for off–great circle propagation over northerly regions [e.g., Zaalov et al , , ; Stocker et al , ; Warrington et al , ]. Recently, there has been some interest in comparing long term model predictions and observations over different paths at high latitudes [e.g., Thrane et al , ; Jodalen et al , ; Goodman and Ballard , ; Stocker et al , ]. Thrane et al [] presented preliminary comparisons of measured and predicted reliability of the HF communication channel at high latitudes and found an overestimation of the reliabilities and MUFs by the Voice of America Coverage Analysis Program (VOACAP) and the Ionospheric Communications Enhanced Profile Analysis and Circuit Prediction Program (ICEPAC).…”

“…Recently, there has been some interest in comparing long term model predictions and observations over different paths at high latitudes [e.g., Thrane et al , ; Jodalen et al , ; Goodman and Ballard , ; Stocker et al , ]. Thrane et al [] presented preliminary comparisons of measured and predicted reliability of the HF communication channel at high latitudes and found an overestimation of the reliabilities and MUFs by the Voice of America Coverage Analysis Program (VOACAP) and the Ionospheric Communications Enhanced Profile Analysis and Circuit Prediction Program (ICEPAC). Goodman and Ballard [] compared observations and VOACAP predictions of the maximum observable frequency in the polar cap and found that the upper decile predicted by VOACAP was lower than the observations, which was attributed to polar patches.…”