Different space weather phenomena significantly impact RF signal propagation, primarily by altering the Earth’s ionosphere and causing direct disturbances. The RF SCYTHE system integrates data related to solar activity and Coronal Mass Ejections (CMEs) to model and predict these effects. Solar activity is monitored through metrics like solar flux, Kp index, and solar wind speed, and can include events like solar flares. These metrics are used to model the ionosphere: Higher solar flux is associated with increased F2 critical frequency (foF2), increased F2 layer height, and higher Total Electron Content (TEC). It influences the calculation of ionospheric attenuation, propagation delay, and TEC. It’s also used to adjust atmospheric density and ionospheric refraction in propagation models. A simplified critical frequency calculation is based on solar flux.The Kp index, an approximation of magnetic activity based on magnetometer readings, contributes to calculations for potential phase shift and propagation delay. It increases F2 layer height during magnetic storms and affects E-layer reflection. It’s also used to influence the probability and intensity of simulated CMEs. High TEC values, correlated with Kp index, can reduce GPS accuracy due to phase distortion and group delay.
Solar Wind Speed: This contributes to calculating potential phase shift and propagation delay.
Solar Flares (measured by X-ray flux): Strong solar flares, indicated by high X-ray flux, primarily affect the D-layer, making it more absorptive for RF signals. Flare classes (C, M, X) are detected based on X-ray flux levels.
Total Electron Content (TEC): This parameter, calculated based on solar flux and Kp index (among other factors like latitude and time of day), is a key indicator of ionospheric conditions. High TEC can cause significant phase distortion and group delay. It also directly impacts attenuation calculations.
Coronal Mass Ejections (CMEs): CMEs are monitored and predicted, with estimations of their intensity and time to Earth.
Based on intensity, CMEs can be predicted to cause HF disruption (intensity > 0.7) and potentially affect VHF (intensity > 0.8).
A CME impact can result in additional attenuation and signal degradation.
The system provides recommendations to prepare for CME impacts, such as considering switching from affected HF bands to VHF/UHF or satellite communications, or being prepared to increase power for VHF.
The effects of these phenomena are incorporated into RF propagation models to calculate metrics such as:
Attenuation: Signal strength reduction due to absorption and scattering.
Phase Shift / Distortion: Changes in the signal’s phase due to varying electron density.
Propagation Delay / Group Delay: The time it takes for the signal to travel, affected by changes in the signal path and speed through the ionosphere.
Reflection Probability: The likelihood that a signal will be reflected by an ionospheric layer, particularly relevant for frequencies below the critical frequency (foF2).
Refraction Angle: The bending of the signal path as it passes through the ionosphere.
MUF (Maximum Usable Frequency): Signals above the MUF calculated for a path are likely to pass through the ionosphere rather than be reflected. Current implementation primarily uses data from sources like NOAA SWPC, GOES satellites, and magnetometers, which are enhanced with space weather observations.
JWST observations are for space weather integration are utilized during RF SCYTHE Ionospheric Models.
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