The June 1965 magnetic storm: Millstone Hill observations

Abstract

Incoherent (Thomson) scatter observations are presented for the F-region electron density over the altitude range 150–650 km during the first 48 hr of a large magnetic storm that occurred in June 1965. These measurements, made at Millstone Hill (42.6°N, 71.5°W), are compared with measurements of the peak electron density N m F2 and total ionospheric electron content n t reported for a number of other stations during the same storm. It is shown that anomalously large values of N m F2 and n t were widely observed during the late afternoon on June 15 and 16, and that these arose because the layer was driven to a much larger height than normal. This motion coincided with the development of a large local increase in the total magnetic field. We suggest that an east-west electric field associated with the asymmetric part ( DS) of the ring current system was responsible for the vertical motion of the layer and hence for the large increases of n t and N m F2 seen in some storms a little before sunset.