Abstract
Abstract. The daily variability of the ionosphere can greatly affect HF or SATCOM communications. HF skywave operators plan frequency schedules months in advance, however, they also require daily knowledge of the ionospheric conditions in order to modify assignments. SATCOM operators also require daily information about the levels of scintillation, which are variations in phase, amplitude, polarisation and angle of arrival that can cause severe degradation of the received signal. Using a number of ionosonde measurements and geomagnetic and solar values, a Daily Ionospheric Forecasting Service (DIFS) has been developed, which provides HF and SATCOM operators with daily forecasts of predicted ionospheric conditions. The system uses in-house algorithms and an externally developed Global Ionospheric Scintillation Model (GISM) to generate HF and SATCOM forecasts. HF forecasts consist of a past summary and a forecast section, primarily displaying observed values and predicted categories for the Maximum Usable Frequency (MUF), as well as an Ionospheric Correction factor (ICF) that can be fed into the ionospheric propagation prediction tool, WinHF. SATCOM forecasts give predictions of global scintillation levels, for the polar, mid and equatorial latitude regions. Thorough analysis was carried out on DIFS and the results conclude that the service gives good accuracy, with user feedback also confirming this, as well.
Highlights
This paper describes the development of a Daily Ionospheric Forecasting System (DIFS) that may be used to enhance the planning and operation of HF and satellite communication
BAE Systems ATC is a member of one of the co-funded Service Development Activity (SDA) groups on this project; it is a member of the Space Weather European Network (SWENET) group, and it was one of first SDA groups to successfully integrate their service with the SWENET
The F2-layer of the ionosphere is the most important for HF radio communications due to its constant presence, its high altitude, which allows for longer communication paths, and the fact that it usually refracts the highest frequencies in the HF range (Davies, 1990)
Summary
The F2-layer of the ionosphere is the most important for HF radio communications due to its constant presence, its high altitude, which allows for longer communication paths, and the fact that it usually refracts the highest frequencies in the HF range (Davies, 1990). The day-to-day variability of the critical frequencies (foF2) is unpredictable, with a 20% variability about the monthly median (CCIR, 1990) and greater than 40% variability during ionospheric storms This directly affects the HF communications by altering the Maximum Usable Frequency (MUF). The graph shows the predicted operating critical frequencies (foF2) is unpredictable, with a 20% variability about the monthly median (CCIR 1990) and greater than 40% variability during ionospheric storms. This directly affects the HF communications by altering the factors, obtained from the Daily Ionospheric Forecast Service (DIFS), which thereby modifies the model on a daily basis to take into accNo.uBntuctcuhrerer:ntDioainloysipohneorsicphceornidciftioornesc.asting service (DIFS) III (a) Fig 1-1 - Channel Assignment for Median Conditions.
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