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Published October 1, 2001 | Published
Journal Article Open

Forecasting the arrival of shock-accelerated solar energetic particles at Earth


Energetic particles accelerated at interplanetary shocks can result in an increased radiation dose for astronauts as well as an increased risk to satellite hardware. These shocks are known to occasionally accelerate protons to energies greater than 100 MeV and can result in very high fluxes. Advanced warning of the arrival of strong interplanetary shocks can enable steps to be taken to minimize the potential risks. In an effort to monitor and assess the radiation risk to astronauts, two real-time count rate monitors were implemented in the Solar Isotope Spectrometer (SIS) on the ACE spacecraft. These rates measure protons with energies >10 and >30 MeV. Since ACE is located at the L1 Lagrangian point, these rates provide information and warning up to 1 hour before an interplanetary shock reaches Earth. Using ACE and GOES, data we have examined examples of shocks and associated energetic particles that have been detected at ACE and were later observed near Earth in an effort to develop more fully the forecasting capability of ACE. Because of the limited amount of solar activity during 1997–1999, this current work is primarily a proof of concept.

Additional Information

© 2001 by the American Geophysical Union. Received June 30, 2000; revised October 25, 2000. Paper number 2000JA000216. We thank the SWEPAM and MAG teams and the ACE Science Center [or providing level 2 data for shock analysis. We thank Adam Szabo for helpful discussions regarding the shock calculations. The GOES data were contributed by the U.S. Department of Commerce, NOAA, Space Environment Center. This work was supported by NASA at the California Institute of Technology (under grant NAG5-6912), the Jet Propulsion Laboratory, and the Goddard Space Flight Center. Janet G. Luhmann thanks Stephen W. Kahler and Ronald D. Zwickl for their assistance in evaluating this paper.

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