Persistent pitch angle anisotropies of relativistic electrons in the
outer radiation belts
Abstract
Pitch Angle Distributions in the radiation belts are well characterized
with sinnα. By tracking the exponent ‘n’, termed Pitch Angle Index, we
are able to observe persistent and cross energy changes in pitch angle
distributions of Van Allen radiation belt electrons using Van Allen
Probes particle observations. The pitch angle distributions measurements
are well fit down to a single satellite spin, and therefore can track
spatially and temporally confined changes to determine connection
between particles and waves. We use the Van Allen Probes data in
conjunction with Geostationary Operational Environmental Satellites
(GOES) spacecraft and several ground magnetometer stations from Canadian
Array for Realtime Investigations of Magnetic Activity (CARISMA) and
Finnish pulsation magnetometer network of Sodankylä Geophysical
Observatory (SGO) to connect particles that become very anisotropic to
electromagnetic ion cyclotron (EMIC) waves during a quiet period over
two days, June 26 and 27, 2013. The waves and peaks in the particle PADs
are both long lasting but spatially separated, suggesting that wave
particle interactions in the inner magnetosphere can occur for extend
periods of time and have significant impact on the global radiation
belts, even during otherwise geomagnetically quiet times and when wave
activity is highly localized.