Ionospheric measurements conducted during the July 11,1991 solar total eclipse at the ionospheric station "El Cerrillo", Mexico

Abstract

A general description of the ionospheric measurements conducted during the solar total eclipse of July 11, 1991 with a C4 - ionospheric sounder at the E1 Cerrillo station in Mexico, is presented. A total of 52 ionograms were obtained from 20 minutes before to 38 minutes after totality. The ionograms cover the 2.5 MHz to the 20 MHz frequency range and are distributed evenly in 1 minute time intervals. They show a clear decrease of the f0 Ft and the foEs values prior to totality and an equally remarkable increase in the recovery phase. The observed variations are similar to those inferred from measurements carried out at the Maui, Hawaii, ionospheric station which was also located along the path of totality of the July 11, 1991 eclipse.