The two PROBA-1/SREM summary plots show the temporal variations of the
proton and electron environment in the Earth's outer radiation belt.
PROBA-1 passes the outer radiation belt region twice per approximately 90
minutes at varying magnetic latitudes. Thus at a given L-shell, observed
variations of the omnidirectional particle fluxes during successive orbits
are combinations of temporal variations and the magnetic latitude effect.
Special care must therefore be taken to distinguish between these two
The values shown in the summary plots represent the temporal variations and
are computed as follows:
1. Average count rates per radiation belt passage (3.0 < L < 7.0) are
computed for the SREM scalers TC3 (proton/electron scaler) and S15 (proton
scaler). Scaler TC3 is sensitive to electrons at E>0.5 MeV and protons at
E>10 MeV and scaler S15 is sensitive to electrons at E>9.5 MeV and protons
at E>10 MeV.
2. For each radiation belt passage an average magnetic latitude is
computed which is used to correct the average count rates for the magnetic
latitude effect. The correction factor is latitude and scaler dependent and
is determined during geomagnetic quiet periods where temporal variations
are assumed to be neglectable. In case of TC3 only a restricted range of
average magnetic latitude is accepted. During belt passages at very high
latitudes the count rates in this scaler are dominated by cosmics.
3. In case of scaler TC3 the corrected average count rates are further
smoothed by applying a sliding average with a window of 12 hours. In case
of scaler S15 no further smoothing is applied.
4. The such computed data points are then plotted versus the medium
time of each selected belt passage.