Speaker
Description
Low Earth Orbit (LEO) polar satellites are vulnerable to the effects of mirror mode events due to their proximity to the Earth’s magnetosphere and ionosphere. Mirror modes are localized magnetic field structures arising from plasma mirror instabilities caused by a pressure anisotropy in the plasma, often in regions with a high plasma beta. Mirror mode events affect LEO satellites via increased risk of radiation damage from surface charging and single event upsets (SEU), arising from auroral proton precipitation modulation and plasma environment density enhancements or depletions, and increased uncertainty in onboard attitude determination systems relying on magnetometers as well as other systems relying on stable magnetic field measurements, because of sudden quasi-periodic drops in the magnetic field. Such mirror events can be detected through satellite observations of particle flux and magnetic field data, as well as ground-based measurements of magnetic perturbation. In this work we propose to combine multi-instrument data from i. POES satellites (NOAA-15,-18,-19) for proton/electron flux anisotropies, energies, and pitch-angles, ii. SWARM for magnetometer data and plasma measurements, iii. Geomagnetic Observatory Neumayer Station III (VNA) located in Antarctica for high-resolution magnetometer time series that can detect the ground magnetic field depression along the magnetic meridian, and iv. S4 scintillation index from GNSS receivers near VNA such as from SANAE, PALM, and MCQI to provide high temporal resolution and sensitivity to short-period mirror wave trains. Mirror modes will first be distinguished from other wave modes with subsequent identification and matching of POES-identified mirror depressions with VNA magnetometer dips and S4 gradients within a defined time window. Information theoretic techniques such as mutual information and conditional mutual information will be used to identify likely mirror events and rule out spurious correlations between the multi-modal datasets. Scores will be assigned to detected mirror mode events based on intensity and duration with higher scores corresponding to more severe events. Score from each modality will also be combined to create a composite mirror mode index. This index benefits space weather forecasting and satellite protection.
