Penetration of solar protons to synchronous altitude

Abstract

Solar proton fluxes in two energy intervals (5–21 Mev and 21–70 Mev) were measured with detectors aboard the geostationary ATS 1 satellite during the solar proton event that began on January 28, 1967. Comparison with data obtained by satellites outside the magnetosphere shows that (a) protons with energies greater than 21 Mev have essentially free access to synchronous altitude; (b) protons in the 5–21 Mev energy interval show a diurnal variation with the flux approaching the interplanetary flux level near local midnight. The transmission efficiency of the magnetosphere is not well organized by either the local (synchronous) magnetic field or the Kp index.

The coupling between the solar wind and proton fluxes at GEO

“…For each of the peaks in SEPs, there is a corresponding peak in the proton flux at GEO on the same day. The higher energy fluxes (0.74-14.5 MeV) studied here are all controlled mainly by the SEP, which was established in the 1960s (Paulikas and Blake, 1969). For the 0.74-4.2 MeV protons, the SEP flux is coupled with the velocity, which suggests that higher solar wind speed could increase the access of the SEPs.…”

“…Paulikas and Blake (1969), using data from GEO satellite ATS 1 and measurements from outside the magnetosphere, showed that during magnetically quiet times, protons with energies > 20 MeV have free access to the geosynchronous regions of the magnetosphere as the theory suggested. However, the energies lower 20 MeV were also shown to have access to the magnetosphere, in contrast to the theories at the time.…”

“…However, the energies lower 20 MeV were also shown to have access to the magnetosphere, in contrast to the theories at the time. Paulikas and Blake (1969) pointed out that these < 20 MeV protons mainly occurred in the nightside sector and concluded that the access of the 5-21 MeV protons is governed by the structure and fluctuations in the magnetic field well outside the GEO. Blake et al (1974) showed that these protons have access to the GEO through the flanks of the magnetosphere and are then temporally trapped with a lifetime of a few drift periods.…”

Substorm aspects of magnetic pulsations

“…SIP's and AIP's, which are more associated with auroral events (3.1), could be related to the electron precipitation which occurs during substorms. Direct access of solar protons (E> 2 MeV) to the magnetosphere during substorms (Martinides and Taorini, 1968;Paulikas and Blake, 1969) could also play a role in the generation mechanism of ULF pulsations.…”

Earth's Radiation Belts.

“…This monotonicity suggests inward radial diffusion from an outer boundary at L 1 10 but does not prove that the particles maintaining the boundary condition originate outside the earth's magnetosphere. Many particles clearly do originate one or more astronomical units from the earth, e.g., solar-flare protons seen at synchronous altitude within hours after the flare [Paulikas and Blake, 1969]. One of the provoca- [1979] that relativistic electrons from Jupiter's magnetosphere [e.g., Krimigis et al, 1975;Iewaldt et al, 1976] help to populate the earth's outer zone at energies 4 5 HeV.…”