Identifying and Characterizing Regions of Relativistic Electron Precipitation into Earth's Atmosphere*

Relativistic electron precipitation (REP) frequently occurs in association with plasma waves, solar wind activity, and other geomagnetic phenomena. REP has been associated with radiation belt losses as well as atmospheric ionization and chemical changes. 

Electron precipitation is attributed to pitch angle scattering from interactions between plasma waves and radiation belt electrons. Field line curvature scattering (FLCS) is another driver of precipitation, occurring when the magnetic field lines are stretched such that their curvature is comparable to the gyroradii of the electrons. These two processes can coexist in the same geomagnetic region and time. Using 12 years of data from the low-earth orbit POES/MetOp satellites, we identify REP events, categorize them based on their driver (either FLCS or waves), and perform a statistical analysis to reveal the REP properties.

REP events often cluster within close temporal and spatial proximity, likely delineating broad precipitation regions. Using the dataset of these events, we examine the distribution of these clusters and their physical properties, such as L-MLT distribution, duration of the cluster, and flux in comparison to more isolated events. Additionally, we analyze the conditions these clusters occur including their association with solar wind structures or plasma waves. Discerning the properties of REP regions is important for determining their relative contribution to electron belt losses and impacts to the atmospheric system.