Question
Which of the following signal paths is most likely to experience high levels of absorption when the A-index or K-index is elevated?
Answer Options
- A) Transequatorial
- B) Through the auroral oval
- C) Sporadic-E
- D) NVIS
Correct Answer: B
Explanation
Elevated A-index and K-index values signify a severe disturbance in the Earth’s magnetic field, typically caused by a geomagnetic storm. This activity results in an influx of charged particles hitting the atmosphere, particularly at high latitudes near the magnetic poles, creating the auroral oval.
When these indices are high, the region within and immediately below the auroral oval experiences intense ionization and turbulence, leading to massive signal attenuation or ‘absorption.’ Therefore, the signal path most likely to experience high levels of absorption is one passing through the auroral oval. This is known as an ‘auroral blackout,’ where HF signals traversing polar paths essentially vanish due to high D-layer absorption.
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