Quantitative Assessment of GOES 8–15 > ${ >} $0.6 and > ${ >} $4 MeV Radiation Belt Electron Fluxes

Abstract On Geostationary Operational Environmental Satellites (GOES) 8–15 (1996–2020), the Energetic Particle Sensor (EPS) included three integral electron channels, with nominal lower energies of 0.6 MeV (E1), 2 MeV (E2) and 4 MeV (E3). The 2 MeV channel has received more attention than the other two channels, because it is used by the NOAA Space Weather Prediction Center for its radiation belt real‐time alerts, and because the characterizations of E1 and E3 were ambiguous, due in part to processing changes between GOES‐12 and ‐13. This paper reports the first cross‐calibration of EPS E1 and E3 with the new Magnetospheric Particle Sensor—High Energy (MPS‐HI) (first flown on GOES‐16). It is based on observations from 2019, when GOES‐15 and ‐17 were separated by 0.6 hr local time on average. The channel response functions ( sr vs. energy) were used three ways: in a bowtie analysis using the method used for the GOES‐17 calibrations; in forward‐model analyses to predict rates for comparison with observations; and in a spectral inversion for comparison of differential energy spectra from the two instruments. The results show that the GOES 13–15 characterizations were more accurate than the GOES 8–12 characterizations, and the bowtie characterization of E3 is still more accurate, while the GOES 13–15 characterization of E1 should continue to be used. The EPS E1 bias with respect to MPS‐HI is 69%. In the E3 energy range, the EPS fluxes are lower than MPS‐HI, from a factor of 2 at 3 MeV to a factor of 5 at 4.4 MeV.