Radio wave propagation and ionisation of meteoric constituents

Abstract

WE have studied from Calcutta (22°34′N; 88°24′E) the effect of meteoric ionisation on radio wave propagation characteristics in the low frequency band, where most radio aids for aerial and marine navigation operate. For the past few years we have been recording during the daytime the field strength of a radio navigational signal on 280 kHz (call sign JR) transmitted from Jessore (23°10′N; 89°10′E), about 110 km from Calcutta. Preliminary results indicated that meteors can produce significant ionisation below the ionospheric regions around 85 km responsible for the reflection of the low frequency signal, causing sizeable radio absorption events during major meteor shower activities1,2. Here we present new results obtained from a detailed analysis of the data for the periods of major meteor showers during a one year period from June 1972 to May 1973, which indicate that the dissipation of the ionised trail produced along the path of a meteor depends on the ionic characteristic of the trail.