Trapped protons in the South Atlantic magnetic anomaly, July through December 1961: 3. Magnetic storms and solar proton events

Abstract

With Injun 1 data for the inner Van Allen zone in the South Atlantic anomaly, it is shown that trapped protons 1 Mev 40 Mev were not affected by the solar proton events and magnetic storms of July–December 1961. In the area near Sao Jose dos Campos, Brazil, for July 14–28, a period of intense and sustained activity with four solar proton events and six magnetic storms, the gross characteristics of the proton fluxes were similar to those for the surrounding quiet periods of July 1–12 and August 2–28: for protons >40 Mev the deviation from the local mean of the total period averages ±19%; for the 1- to 15-Mev protons, ±29%. For the region near Salisbury, Southern Rhodesia, the data were examined for intervals within the August–December period, which contained one major and four minor solar-proton events and eleven storms. Here, in their gross characteristics, protons >40 Mev had an average stability of ±30% and 1- to 15-Mev protons, ±31%. In a detailed examination for protons >40 Mev, a stability to within an average of ±7% was found to exist at seventeen points in B-L space, each point being sampled more than once by the satellite during the July–December period. In addition, these (high energy) particles had an unchanging flux in the slot (2.1 < L < 2.5) marking for these protons the outer boundary of the inner Van Allen zone, a region where the intensities are consistently low and, hence, where changes can be readily detected. The study of the inner zone behavior during the solar proton magnetic storm event of September 28 to October 4 yields results at least suggestive of an unchanging inner zone character during the event itself.