A synoptic study of the F2-region of the ionosphere in the Asian zone

Abstract

A detailed study of the variation of ƒ₀F2 at ionospheric stations in the Asian zone shows that the region of maximum ƒ₀F2 varies with the time of the day as well as with the season. The anomalous belt of the F2-layer develops at the equator near sunrise and slowly expands with the progress of the day, and is most extended during the afternoon hours. Multiple splittings in the F-region and other abnormal P'-ƒ recordings observed at middle latitudes are shown to be associated with some striking features in the synoptic distribution of ƒ₀F2. The abnormal recordings can be explained on the basis of horizontal movements in the ionosphere, being in the eastwest direction before sunrise in the morning or after sunset in the evening, and in the north-south direction during the forenoon.