Variation of geomagnetic index empirical distribution and burst statistics across successive solar cycles
Earth’s magnetosphere and ionosphere have their own space weather. Space weather storms can cause technological problems including electrical grid damage and satellite system disruption. The overall driving of space weather follows the solar cycle of activity which has a period of approximately 11-years. Geomagnetic indices, based on magnetic field observations at the Earth’s surface, provide almost continuous monitoring of magnetospheric and ionospheric activity. We analyze two geomagnetic index time series, AE and SMR, which track activity in the auroral region and around the Earth’s equator, respectively. We identify bursts or excursions above thresholds in the AE and SMR time series. We find that the ratio of average burst duration to return period provides a useful activity parameter which tracks the solar cycle in a well-defined way. No two solar cycles are the same, each solar maximum has a different strength. However, the distributions of the bursts, and the observations from which they are constructed, have properties that repeat from one solar cycle to the next. These results provide constraints that could be used in model predictions for the statistics of future space weather on solar cycle scales.
Bergin, A., Chapman, S. C., Moloney, N. R., & Watkins, N. W. (2022). Variation of geomagnetic index empirical distribution and burst statistics across successive solar cycles. Journal of Geophysical Research: Space Physics, 127, e2021JA029986. https://doi.org/10.1029/2021JA029986