Relativistic microburst storm characteristics: Combined satellite and ground-based observations

We report a comparison of SAMPEX detected relativistic electron microbursts and short-lived subionospheric VLF perturbations termed FAST events, observed at Sodankylä Geophysical Observatory, Finland, during 2005. The observed FAST event perturbation decay times were consistent with ionospheric recovery from bursts of relativistic electron precipitation. Our study strongly suggests that the region over which microbursts occur during storm event periods can be at least ~90° in longitude (~6 hours in MLT). This confirms earlier estimates of microburst storm size, suggesting that microbursts could be a significant loss mechanism for radiation belt relativistic electrons during geomagnetic storms.