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PoS(ICRC2017)118

Solar Proton Transport to Earth

E. Bramlitt

in 35th International Cosmic Ray Conference

Contribution: pdf

Abstract

ABSTRACT.  Since 1976 the USA weather satellites named GOES, followed by a sequence number, have continuously monitored the Sun for proton emissions. The monitoring data is a valuable resource available online, but it is not being fully utilized. To encourage use, procedures are detailed for downloading GOES data to a Windows 10 computer with Excel software. Excel makes easy the calculation of proton velocity, pace, and rigidity given energy, which GOES registers in eleven channels from 2.5 to >700 MeV. Plots of pace versus time protons arrive at GOES are linear, zero pace is emission time, and line slope is proton path length. Proton flux at GOES is an indicator of neutron flux at commercial aircraft on polar routes, and dose to aircraft occupants is calculable from flux. January 2014 is chosen to demonstrate some uses of GOES data. Proton emission started on January 6 around 7:30, flux of 100 MeV protons began a sharp increase coincident with neutron monitor count rate increases causing GLE 72, and the emission continued for four days with several emission bursts. The January 8 burst (25-hr width at half max) is shown to cause >6 milli-Sievert dose at high-latitude flight levels. For perspective, Germany requires air crewmembers be grounded by that dose and have medical follow-up. In conclusion, GOES data cover 270 proton events during which there were 41 GLE, so January 2014 is a tip of the iceberg.