Some characteristics of the ELF/VLF radio noise measured near L´Aquila, Italy

Measurements are reported of radio noise by an ELF/VLF radiometer located near L´Aquila, Italy, which at ELF/VLF frequencies can be considered a typical location for the Mediterranean area. The measurements provide information on the average and root mean square (RMS) amplitudes in 16 narrow frequency bands (5% bandwidth) distributed through the range of 10 Hz to 32 kHz. Later processing of these data gives the V_d statistic, which is a measure of the impulsiveness of the noise. The L´Aquila noise amplitudes tend to be higher during the summer than during the winter, particularly at the higher frequencies covered by the measurements, and the afternoon and evening amplitudes also tend to be higher than those measured at other times during the day. The amplitudes decline with increasing frequency approximately as f^-1, whereas V_d tends to increase with frequency, indicating increased impulsiveness at the higher frequencies