Reply on AC2

Abstract

<strong class="journal-contentHeaderColor">Abstract.</strong> Relativistic radiation belt electron observations from the Energetic Particle Telescope (EPT) onboard the PROBA-V satellite are compared to those performed by the Magnetic Electron Ion Spectrometer (MagEIS) onboard the Van Allen Probes (VAPs) formerly known as the Radiation Belt Storm Probes (RBSP). Despite their very different orbits, both instruments are able to measure fluxes of electrons trapped on a given magnetic shell. In the outer belt, the comparison of high and low altitude fluxes is performed during the first three months of 2014, featuring the most intense storms of the year. In the inner belt, measurements from the two instruments are compared only at conjunction, when the satellites are physically close to each other. Due to the low number of conjunctions, the whole period of mutual operation of both instrument is used (i.e. May 2013&ndash;October 2019). The comparisons show that flux variations appear simultaneously on both spacecraft, but the fluxes observed by the EPT are almost always lower than for MagEIS, as expected from their different orbits. In addition, this difference in flux intensity increases with electron energy. During geomagnetic storms, it is also shown that dropout events (i.e. sudden depletion of electrons) in the outer belt are more pronounced at low altitudes than near geomagnetic equator. The effect of the equatorial pitch angle value of electrons is investigated in the outer belt. The results show a good agreement between observations of the two instruments, especially if low pitch angle electrons near the equator are considered.