Forenoon bite-out in f0F2 at low latitudes

Abstract

Evidence is presented showing that the longitudinal extent of the forenoon bite-out in f0F2 at low geomagnetic latitudes can sometimes be very narrow and that marked differences in the extent of the development of the bite-out can occasionally occur at locations separated in longitude by about three hours. Published hourly f0F2 data from Ahmedabad (23.02 deg N, 72.60 deg E; mag. lat., 18.6 deg N) and Chung-Li (24.95 deg N, 121.23 deg E; mag. lat., 18.6 deg N) for a 24-month period (January 1966-December 1967) on the ascending phase of the 20th solar cycle are examined for the presence of the forenoon bite-out. This bite-out is taken to be present when the depression in f0F2 in the forenoon period is 0.5 MHz or more from the normal assumed trend. The bite-out is found to be present on 25 days at Ahmedabad and 19 days at Chung-Li. Only on 14 days is it evident at both stations.