Many models of the solar wind drivers of magnetospheric and ionospheric processes rely on measurements near the L1 Sun-Earth libration point. The NASA OMNI website[1] provides a database of such values time-shifted to a model Bow Shock (BS) nose location. However, it is important to quantify the uncertainty in the timing and evolution of solar wind conditions between L1 and the magnetospheric boundary.
This study compares 1-min cadence OMNI measurements with magnetic field (B) and plasma measurements from two Earth-orbiting ESA Cluster[2] satellites over a 22-year period. We have compiled a database of periods for which Cluster are located in the solar wind, guided by automated BS crossing detection based on step changes in B-field magnitude and variance. This provides over 5000 hours for which both OMNI and Cluster B-field and plasma measurements (density, velocity, temperature) are available.
This paper presents our methodology, inter-spacecraft comparisons of solar wind conditions, and discussions on the inclusion or exclusion of foreshock regions and timing offsets between spacecraft offset from the BS nose.
References
1. Papitashivili, N. E. (2024). OMNIweb. https://omniweb.gsfc.nasa.gov.
2. Laakso, H., et al. (2010), Cluster Active Archive: Overview. https://doi.org/10.1007/978-90-481-3499-1_1