Response of the Total Electron Content of the Ionosphere Over North America to the Total Solar Eclipse of 26 February 1979
Document ID: 58
Essex, E. A.1
Klobuchar, J. A.1
Philbrick, C. Russell1
Leo, R.2
1 USAF, Geophysics Laboratory, Hanscom AFB, Bedford, MA, U.S.A.
2 Montana State University, Electronics Research Laboratory, Bozeman, MT, U.S.A.
Presented: Indian National Science Academy, 48, 1982
Abstract
Ionospheric total electron content (TEC) observations were carried out from eight stations during 26 February 1979 total solar eclipse over North America. The TECs were determined from the Faraday rotation of the plane of polarization of the VHF signal from geostationary satellites. Local times of totality of the eclipse in the ionosphere observed from the various stations ranged from 0734hr to 1400hr. Depletion of the ionospheric total electron content from the non-eclipse average behaviour varied up to a maximum of 40 per cent for the ionosphere experiencing 100 per cent eclipse. Maximum TEC depletion occurred on average 33 minutes after maximum contact. Most of the stations showed a rapid rate of depletion of TEC about 30 minutes after first contact, the rate of depletion reaching a minimum value at or before maximum obscuration. Before fourth contact was reached, the rate of increase of TEC generally had overshot the noneclipse day average, gradually returning to that average after the fourth contact. Using ionosonde data, it was found that the peak density of the F-region and the TEC varied by approximately the same amount at those stations for which the E-region had formed before first contact of the eclipse. Slab thicknesses were not significantly changed during the eclipse.
Keywords: total electron content, Faraday rotation, plane of polarization, HF signal, geostationary satellite, Ionograms