Global Measurements of Low-Frequency Radio Noise
We report illustrative results obtained by Stanford University’s global survey of ELF/VLF radio noise (frequencies in the range 10 Hz – 32 kHz). Particular comparison is made between the noise measurements made at high (polar) latitudes with those at lower latitudes. Although most of the natural ELF/VLF noise observed everywhere in the world is lightning-generated, the high-latitude noise often contains additional components that are of magnetospheric origin. In the data we have examined, this noise consists predominantly of polar chorus, which is concentrated in the range 300 Hz–2 kHz. It produces a characteristic signature in the noise statistics. Less frequent occurrences of broad-band (auroral) hiss can occasionally mask most or all of the lightning-generated noise in the ELF/VLF range.
KeywordsNoise Statistic Average Amplitude Narrow Band Frequency Radio Noise Arrival Height
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