Abstract:
Published ionospheric data were used as a basis to study the characteristics of nighttime Es (blanketing frequency, virtual height, and transparency range) at Kodaikanal (geomag. lat.: 0.6 N; dip: 3.5 N) with the object of determining whether the longitudinal dependence of nighttime Es occurrence applies also to other nighttime Es characteristics. The analysis covers periods of low and high solar activity. A longitudinal dependence of the nighttime Es characteristics is established. It is shown that both the blanketing frequency and the transparency range are independent of solar activity. The distribution of virtual height exhibits a distinct local time variation whose characteristics differ for periods of low and high solar activity.
