Abstract
AbstractUsing National Oceanic and Atmospheric Administration Polar Orbiting Environmental Satellite (NOAA/POES) observations of energetic protons, we for the first time investigated statistical properties of a specific type of particle precipitation—localized precipitation of energetic protons (LPEP) equatorward of the isotropy boundary. The maximum occurrence rate was found in the day‐afternoon sector at L > 6. The maximum precipitating flux is found at lower L shells (L = 4–5). The dependence of LPEP occurrence and intensity on the geomagnetic activity indices and solar wind parameters is investigated. In particular, while the precipitating proton flux increases with geomagnetic activity everywhere, the occurrence rate in the day‐afternoon sector at L > 6 decreases under the strongest activity. We conclude that revealed LPEP properties are mostly similar to those obtained for electromagnetic ion cyclotron waves on the basis of data from previous spacecraft missions. This similarity supports the suggestion on LPEP as the result of ion cyclotron instability in the magnetosphere.
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