A further investigation of the ariel 4 ambient electron densities at vernal equinox

Ariel 4 satellite electron density data returned by the rf-capacitance probe on board are further investigated in order to seek any possible signature of the magnetic cusp in two different hemispheres during magnetically quiet periods at the 1972 vernal equinox. Ariel 4 electron density data covering the middle and high invariant magnetic latitudes at around 550 km altitude, for 91 days centered on the March 1972 equinox are employed. The data revealed a strong magnetic local time (MLT) dependence. The cusp signature was clearly in the Northern Hemisphere.