Operational Nowcasting of Electron Flux Levels in the Outer Zone of Earth's Radiation Belt

Abstract. The nonlinear autoregressive moving average with exogenous inputs (NARMAX) system identification technique is applied to various aspects of the magnetospheres dynamics. It is shown, from an example system, how the inputs to a system can be found from the error reduction ratio (ERR) analysis, a key concept of the NARMAX approach. The application of the NARMAX approach to the Dst (disturbance storm time) index and the electron fluxes at geostationary Earth orbit (GEO) are reviewed, revealing new insight into the physics of the system. The review of studies into the Dst index illustrate how the NARMAX approach is able to find a coupling function for the Dst index from data, which was then analytically justified from first principles. While the review of the electron flux demonstrates how NARMAX is able to reveal new insight into the physics of the acceleration and loss processes within the radiation belt.

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Electron flux enhancement in the inner radiation belt during moderate magnetic storms

Annales Geophysicae ◽

10.5194/angeo-25-1359-2007 ◽

2007 ◽

Vol 25 (6) ◽

pp. 1359-1364 ◽

Cited By ~ 10

Author(s):

H. Tadokoro ◽

F. Tsuchiya ◽

Y. Miyoshi ◽

H. Misawa ◽

A. Morioka ◽

...

Keyword(s):

Radiation Belt ◽

Electron Flux ◽

Recovery Phase ◽

Magnetic Activity ◽

Magnetic Storms ◽

Natural Phenomena ◽

Early Recovery ◽

Flux Enhancement ◽

Angle Scattering ◽

Order Of Magnitude

Abstract. During moderate magnetic storms, an electron channel (300–1100 keV) of the NOAA satellite has shown sudden electron flux enhancements in the inner radiation belt. After examinating the possibility of contamination by different energetic particles, we conclude that these electron flux enhancements are reliable enough to be considered as natural phenomena, at least for the cases of small to moderate magnetic storms. Here, we define small and moderate storms to be those in which the minimum Dst ranges between −30 and −100 nT. The electron flux enhancements appear with over one order of magnitude at L~2 during these storms. The enhancement is not accompanied by any transport of electron flux from the outer belt. Statistical analysis shows that these phenomena have a duration of approximately 1 day during the period, starting with the main phase to the early recovery phase of the storms. The flux enhancement shows a dawn-dusk asymmetry; the amount of increased flux is larger in the dusk side. We suggest that this phenomenon could not be caused by the radial diffusion but would be due to pitch-angle scattering at the magnetic equator. The inner belt is not in a stationary state, as was previously believed, but is variable in response to the magnetic activity.

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Multi-satellite simultaneous observations of magnetopause and atmospheric losses of radiation belt electrons during an intense solar wind dynamic pressure pulse

Annales Geophysicae ◽

10.5194/angeo-34-493-2016 ◽

2016 ◽

Vol 34 (5) ◽

pp. 493-509 ◽

Cited By ~ 15

Author(s):

Zheng Xiang ◽

Binbin Ni ◽

Chen Zhou ◽

Zhengyang Zou ◽

Xudong Gu ◽

...

Keyword(s):

Solar Wind ◽

Radiation Belt ◽

Pressure Pulse ◽

Electron Flux ◽

Dynamic Pressure ◽

Energetic Electron ◽

Solar Wind Dynamic Pressure ◽

Angle Scattering ◽

Radiation Belt Electrons ◽

Atmospheric Loss

Abstract. Radiation belt electron flux dropouts are a kind of drastic variation in the Earth's magnetosphere, understanding of which is of both scientific and societal importance. Using electron flux data from a group of 14 satellites, we report multi-satellite simultaneous observations of magnetopause and atmospheric losses of radiation belt electrons during an event of intense solar wind dynamic pressure pulse. When the pulse occurred, magnetopause and atmospheric loss could take effect concurrently contributing to the electron flux dropout. Losses through the magnetopause were observed to be efficient and significant at L ≳ 5, owing to the magnetopause intrusion into L ∼ 6 and outward radial diffusion associated with sharp negative gradient in electron phase space density. Losses to the atmosphere were directly identified from the precipitating electron flux observations, for which pitch angle scattering by plasma waves could be mainly responsible. While the convection and substorm injections strongly enhanced the energetic electron fluxes up to hundreds of keV, they could delay other than avoid the occurrence of electron flux dropout at these energies. It is demonstrated that the pulse-time radiation belt electron flux dropout depends strongly on the specific interplanetary and magnetospheric conditions and that losses through the magnetopause and to the atmosphere and enhancements of substorm injection play an essential role in combination, which should be incorporated as a whole into future simulations for comprehending the nature of radiation belt electron flux dropouts.

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