Subauroral Crosstalk in POES/Metop TED Channels

Abstract. Particle measurements from the Polar Operational Environmental Satellites (POES) and their successor, the Meteorological Operational (Metop) satellite program, are widely used for various scientific applications. While most studies focus on the Medium Energy Proton and Electron Detector (MEPED), the low-energy (eV and keV) counterpart, the Total Energy Detector (TED), has received comparatively less attention. However, the recent rise in the altitudes considered in ionization and climate models has increased interest in low-energy particle measurements as inputs for atmospheric ionization models.

This study analyzes TED particle data (along with selected MEPED channels) from 2001 to 2018 and demonstrates that, in particular, the TED 0° proton channels – and, to a lesser extent, other TED channels as well as the MEPED proton channels P1, P2, and P3 – are contaminated by energetic electrons at L < 6 (with the exception of TED electron band 4). In some cases, the contaminated fluxes exceed typical auroral flux levels. The affected regions were cross-validated using auroral UV emissions and occurrences of GNSS derived S4 index to rule out the possibility that the observed fluxes correspond to real particle precipitation.

Additionally, we established a Kp- and channel-dependent latitude boundary that may serve as a simple cut-off criterion for the contaminated regions. Furthermore, we propose a more general flux correction approach based on background count measurements.