Empirical determination of solar proton access to the atmosp

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TitleEmpirical determination of solar proton access to the atmosphere: Impact on polar flight pathsAbstractViolent expulsions on the Sun's surface release high energy solar protons that ultimately affect HF communication used by aircraft. The geomagnetic field screens the low altitude equatorial region, but these protons can access the atmosphere over the poles. The latitudes over which the solar protons can reach vary with geomagnetic indices such as Kp and Dst. In this study we use observations from low Earth orbit to determine the atmospheric access of solar protons and hence the flights paths most likely to be affected. Observations taken by up to six polar orbiting satellites during 15 solar proton events are analyzed. From this we determine 16,850 proton rigidity cutoff estimates across three energy channels. Empirical fits are undertaken to estimate the most likely behavior of the cutoff dependence with geomagnetic activity. The changing Kp value is found to lead the variation in the cutoffs by âˆ¼3 h. We provide simple equations by which the geomagnetic latitude at which the protons impact the atmosphere can be determined from a given Kp or Dst value. The variation found in the cutoff with Kp is similar to that used in existing operational models, although we suggest that a âˆ¼1-2Â Degrees equatorward shift in latitude would provide greater accuracy. We find that a Kp predictive model can provide additional warning to the variation in proton cutoffs. Hence, a prediction of the cutoff latitudes can be made âˆ¼3 h to as much as 7 h into the future, meeting suggested minimum planning times required by the aviation industry. Â© 2013. American Geophysical Union. All Rights Reserved.

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1st AuthorNeal, J. AuthorNeal, J.Rodger, C.Green, J.Year2013JournalSpace WeatherVolume11Number7Pages420-433DOI10.1002/swe.20066URLhttps://www.scopus.com/inward/recor.....706db707d6742029ca44caeadAuthor KeywordsPOES spacecraftpolar cap absorptionsolar proton events

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CitationNeal, J., Rodger, C. and Green, J. (2013). Empirical determination of solar proton access to the atmosphere: Impact on polar flight paths. Space Weather, 11(7):420-433