Occurrence rates of proton IBs on flanks and dayside

Determine the occurrence rate of proton isotropy boundaries on the magnetospheric flanks and dayside by acquiring sufficient observations to overcome current undersampling and establish reliable statistics.

Background

The authors report near-unity occurrence of proton IBs between 19 and 03 MLT, with rates apparently trending downward toward the flanks. However, ELFIN’s coverage was insufficient on the flanks and dayside, preventing determination of occurrence rates there.

Resolving the occurrence rates in these sectors is necessary for a complete global picture of proton IB behavior and for validating models of nightside-to-dayside IB occurrence.

References

The plot shows that proton IBs are observed by ELFIN between 90% to ∼100% of the time between 1900 and 0300 MLT, with occurrence rates trending downward toward the flanks (ELFIN again had too few collections to determine the proton occurrence rates there or on the dayside).

— Statistical Characteristics of the Proton Isotropy Boundary  (2409.04488 - Wilkins et al., 2024) in Section 4 (Results), discussion of Figure 4 (top panel)