Sunday decreases in magnetospheric VLF wave activity

Abstract

Magnetospheric wave intensity in the 2‐ to 4‐kHz range was monitored on the ground at Siple, Antarctica, in 1974 and 1975. Sampled broadband spectral data show that the wave activity in the 2‐ to 4‐kHz band is predominantly chorus (discrete narrow band emissions). The measured wave intensity shows a distinct minimum on Sunday in comparison with the rest of the week. The Sunday minimum is confined to the dawn‐afternoon local time sector where the chorus intensity has a diurnal maximum. It is suggested that much of the chorus observed at Siple is triggered in the magnetosphere by power line radiation from its conjugate region in eastern Canada and that the Sunday minimum in magnetospheric wave activity is the result of reduced power consumption on Sunday. This interpretation is supported by the results of an independent study based on broadband spectral data from Siple between 1973 and 1975. The results show weekly variations in the occurrence of strong power‐line‐induced emissions with a pronounced minimum on Sunday. This pattern is similar to the power consumption pattern in Quebec. It appears that power line radiation is an important factor in the overall magnetospheric wave environment. Its role in particle precipitation (through wave‐particle interaction) needs to be investigated.