I am analyzing data from an instrument that measures low energy electron flux at Geo-Stationary orbit. There are sharp oscillations in the particle flux of 30 eV electrons occurring from about noon to 8 pm (space-craft local). The period of this activity is relatively consistent at about one cycle every 13 minutes. I am trying to determine if this is a natural phenomenon or systemic contamination.

EDIT: I have added a plot of data containing the oscillations. The Y-axis represents counts per interval and X axis is time. The purple line represents the south-most zone and the red the north-most. I have intentionally removed the title/legend/labels. The oscillations are obvious in the right side of the plot.

30 eV electron counts for all zones.  Purple and Red lines are South-most and North-most zones respectively.

My question is this:

Are there any natural cycles within the solar-wind or radiation belts that have a similar frequency?

A second question:

Are there evenly spaced and distinct longitudes containing higher densities of electron cycling that the space-craft might be passing through?

Any other ideas as to the cause of the oscillation are welcome.

  • $\begingroup$ Any other experiments which have observed this effect? Which direction are you looking (at Earth, at the sun, tangent to orbit)? $\endgroup$ Jul 27, 2018 at 17:51
  • $\begingroup$ @CarlWitthoft The effect is not present in any other energy ranges or protons of the same energy range. It is strictly in the lowest energy electron channel. I have found no other examples of this behavior from publicly available data. The field of view of the instrument sweeps from directly south to directly north with the mid pointing zones facing anti-earthward. It can be seen in all the zones, but it is most pronounced in the zones receiving the highest flux, which are the north and south-most zones. $\endgroup$
    – A McKelvy
    Jul 27, 2018 at 18:00
  • $\begingroup$ The only thing in that frequency range that might affect these would be something like PC waves, but I don't recall which ones are around 10 minutes (e.g., PC-1, PC-2, etc.). I also don't recall why they are called PC waves, but no matter. That'd be the first place to check. I would also look at fluxgate magnetometer data and filter it to look for oscillations with periods near 10 minutes. If you see none, then this is a local artifact. $\endgroup$ Aug 31, 2021 at 15:20


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