A global response of the total electron content of the ionosphere to the magnetic storm of 17 and 18 June 1972

A global study is made of the response of the total electron content of the ionosphere to the sudden commencement (S.C.) geomagnetic storm of 17 June 1972. Using data from 18 sites, a comparison is made of the seasonal differences between this storm and the 17 December 1971 ionospheric storm studied on a similar global basis. When storm induced total electron content enhancements occur, they generally occur within 24 h of the S.C. and they tend to be larger in the winter hemisphere; subsequent depletions are generally more severe in the summer hemisphere. The best-defined storm effect is the positive phase evening enhancements seen in the American longitude sector. The local times of the peak enhancements show a coupled seasonal/longitudinal/latitudinal pattern with latitude being the clearest ordering parameter. The magnitudes of the subsequent negative phase depletions show a longitudinal gradient from east to west. (author)