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- Title
Dynamical Properties of Peak and Time‐Integrated Geomagnetic Events Inferred From Sample Entropy.
- Authors
Mourenas, D.; Artemyev, A. V.; Zhang, X.‐J.
- Abstract
We provide a comprehensive statistical analysis of the sample entropy of peak and time‐integrated geomagnetic events in 2001–2017, considering different measures of event strength, different geomagnetic indices, and a simplified solar wind‐magnetosphere coupling function P*. Our investigations reveal the existence of significant correlations between the entropies of Dst, ap, and P*, and between such entropies and event strengths, as well as good correlations between peak levels of solar wind‐magnetosphere coupling and ring current (Dst) and ap entropies, suggesting a potential predictability of significant Dst and ap events on the basis of appropriate functions of P*. Sensibly weaker correlations are found with AE entropy. We further show the presence of several significant entropy correlations between geomagnetic indices, solar wind‐magnetosphere coupling, and trapped or precipitated energetic electron and ion fluxes measured by geostationary and low Earth orbit satellites in the outer radiation belt during the same periods. Entropy correlations between Dst and trapped or precipitated 30‐ to 80‐keV ion fluxes at low L and between AE and trapped 40‐keV electron fluxes at geostationary orbit correspond well with ring current properties and substorm‐induced injections, respectively. Entropy correlations between ap and precipitation rates of energetic ion and electron fluxes demonstrate the sensibility of ap index entropy to both low‐energy (5–30 keV) electron injections and ring current. The stronger entropy correlation between solar wind‐magnetosphere coupling and ap than AE likely stems from the more stochastic behavior of electron injections and fast losses near geostationary orbit. Plain Language Summary: We analyze statistically the entropy of geomagnetic events in 2001–2017. We look for significant relationships between different entropies and different measures of event strength. Our investigations reveal important correlations between the entropies of Dst index, ap index, and a solar wind‐magnetosphere coupling function P*, as well as between such entropies and event strengths. Peaks of solar wind‐magnetosphere coupling are found to be well correlated with ring current (Dst) and ap entropies, suggesting a potential predictability of strong Dst or ap geomagnetic events on the basis of P*. Examining trapped and precipitated energetic electron and ion fluxes simultaneously measured by geostationary and low Earth orbit satellites in the outer radiation belt, we find important entropy correlations between Dst and trapped or precipitated ion fluxes, as well as between AE and trapped electron fluxes at geostationary orbit, corresponding to ring current variations and the effects of substorm‐induced injections, respectively. We also demonstrate the sensibility of ap index entropy to both low‐energy electron injections and ring current. The stronger entropic link found between the solar wind driving and ap than AE is likely due to the presence of more stochastic electron injections and fast losses near geostationary orbit than closer to the Earth. Key Points: Geomagnetic events entropies are correlated with event strengths, energetic particle flux entropies, and inter‐correlatedAE entropy is less correlated with other entropies, probably due to stochastic processes more frequent at geostationary orbitPeak values of solar wind‐magnetosphere coupling are well correlated with ring current (Dst) and ap entropies
- Subjects
GEOMAGNETISM; ENTROPY; QUANTITATIVE research; MAGNETOSPHERE; RING currents
- Publication
Journal of Geophysical Research. Space Physics, 2020, Vol 125, Issue 2, p1
- ISSN
2169-9380
- Publication type
Article
- DOI
10.1029/2019JA027599