Study of variations in the absorption of cosmic radio noise using Riometer at Casey station

摘要

Cosmic noise is received at 30MHz by a solid state riometer with dual dipole antenna at Casey (Australian Antarctic Division) station (66.20S, 110.50E). This kind of measurement is useful to determine the absorption in the lower ionospheric D region. This paper is concerned with the study of Seasonal and annual variations in the cosmic radio noise absorption by average method. The weak fluctuating average cosmic noise absorptions ( 1 dB) were recorded at 30 MHz during whole study. In this paper, we discussed seasonal and annual variability of cosmic noise absorption data during the period of low and comparatively moderate solar activity since from last three years. From the result of data analysis, it is observed that the average absorption of 2011 was maximum (0.06966 dB) due to sudden ionospheric disturbances recorded during the year.