Drift Echoes at Geostationary Orbit: An Eight‐Year Climatology From GOES‐16
Journal Article
Overview
abstract
Abstract; Drift echoes are energy‐dispersed recurrences in energetic particle flux that appear when a localized injection or compression organizes trapped ions and electrons according to their azimuthal drift. Although established as tracers of radiation‐belt dynamics, drift echoes have rarely been surveyed statistically at geostationary orbit. We apply an automated, sliding‐window implementation of the CLEAN algorithm, followed by a multi‐channel energy–period consistency classifier, to 8 years (January 2017–April 2025) of Magnetospheric Particle Sensor–High Energy measurements on GOES‐16, obtaining a catalog of 48,876 valid electron and 35,811 valid proton drift echo detection windows. The detected drift periods decrease with particle energy, from to minutes across the 56–939 keV electron channels and from to minutes across the 96–849 keV proton channels, and lengthen toward off‐equatorial pitch angles, in agreement with gradient and curvature drift theory; their variation with magnetic local time is weak and consistent with the non‐dipolar geostationary field rather than with a genuine local‐time variation of any single particle's drift period. Conditioning the catalog on the upstream interplanetary magnetic field (IMF) shows that the IMF clock angle strongly organizes the magnetic local time at which detections peak—clock angles near and favor a noon‐to‐dusk peak and those near and a dawn‐to‐noon peak—while leaving the central period unchanged. The catalog counts detection windows rather than individually resolved injections, leaving event‐level association to future work. The survey establishes drift echo climatology from operational geostationary particle data and distinguishes internal drift physics from external solar‐wind control.
