IPS of the Radio Source 3C48 During the Periods of Low and High Solar Activity

Abstract:

We present a comparative study of three techniques used to estimate the scintillation index (m) using interplanetary scintillation (IPS) observations carried out by the Big Scanning Array (BSA), that operates at a frequency of 111 MHz. These techniques are based on: rms analysis on-source and off-source (classic), Fourier and wavelet transforms. IPS data are analyzed separately for the period of low solar activity (2007-2009), and for the year 2013, near the solar activity maximum. Our results show that in general, these methods are equivalent. We analyze the radial dependence of scintillation index at meter wavelengths during these two periods. It is found that the observed radial dependence of scintillation index during both periods of the cycle 24 is more flat than the theoretical dependence expected for the case of solar wind spherical symmetry. This flattening can be explained in terms of the influence of the heliospheric current sheet during periods of low solar activity, and the influence of solar disturbances, such as coronal mass ejections (CMEs), for periods of high solar activity.