Occurrence rate and duration of space weather impacts on high-frequency radio communication used by aviation | Journal of Space Weather and Space Climate

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Table 1

Parameters and activity levels describing MOD and SEV level activity for shortwave fadeout (SWF), auroral absorption (AA), polar cap absorption (PCA), and post-storm maximum usable frequency depression (PSD) based on ICAO regulations (ICAO, 2019).

Sub-effect	Parameter	MOD	SEV
SWF	Solar X-ray flux (0.1–0.8 nm wavelength) (Wm⁻²)	1 × 10⁻⁴ (X1)	1 × 10⁻³ (X10)
AA	Kp index	8	9
PCA	Absorption at 30 MHz (dB)	2	5
PSD	MUF^*	30%	50%

Compared to a 30-day running median of the critical frequency of the foF2.

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