Proton Flux Variations During Solar Energetic Particle Events, Minimum and Maximum Solar Activity, and Splitting of the Proton Belt in the South Atlantic Anomaly

V. Pierrard; S. Benck; E. Botek; S. Borisov; A. Winant

doi:10.1029/2022JA031202

Proton Flux Variations During Solar Energetic Particle Events, Minimum and Maximum Solar Activity, and Splitting of the Proton Belt in the South Atlantic Anomaly

V. Pierrard, S. Benck, E. Botek, S. Borisov, A. Winant

Research output: Contribution to journal › Article › peer-review

5 Scopus citations

Abstract

The analysis of the proton flux variations observed by the Energetic Particle Telescope (EPT) at energies >9.5 MeV from the launch of PROBA-V satellite on 7 May 2013 up to October 2022 shows an anti-correlation between the proton fluxes and the solar phase. At solar minimum, the fluxes are higher at low L corresponding to the northern border of the South Atlantic Anomaly (SAA). This solar cycle modulation of the inner belt is mainly due to losses by increased atmospheric interactions during solar maximum. Strong Solar Energetic Particle (SEP) events, like in January 2014, June 2015, and September 2017, inject energetic protons at high latitudes, but not in the inner belt where protons are trapped at long term at low L. Nevertheless, big geomagnetic storms, including those following SEP a few days after, can cause losses of protons at the outer border of the proton belt, due to magnetic field perturbations. A double peak in the proton belt is observed during long period of measurements only for the EPT channel of 9.5–13 MeV. The narrow gap between the two peaks in the inner belt is located around L = 2. This resembles to a splitting of the proton belt, separating the SAA into two different parts, North and South. The high-resolution measurements of PROBA-V/EPT allow the observation of small-scale structures that brings new elements to the understanding of the different source and loss mechanisms acting on the proton radiation belt at LEO.

Original language	English
Article number	e2022JA031202
Journal	Journal of Geophysical Research: Space Physics
Volume	128
Issue number	5
DOIs	https://doi.org/10.1029/2022JA031202
State	Published - May 2023
Externally published	Yes

Bibliographical note

Publisher Copyright:
© 2023. The Authors.

Funding

The project 21GRD02 BIOSPHERE has received funding from the European Partnership on Metrology, co‐financed by the European Union's Horizon Europe Research and Innovation Programme and by the Participating States. This research was supported by the International Space Science Institute (ISSI) in Bern, through ISSI International Team project #477 (Radiation Belt Physics From Top To Bottom: Combining Multipoint Satellite Observations And Data Assimilative Models To Determine The Interplay Between Sources And Losses). All authors are grateful to the PROBA‐V/EPT teams at B.USOC and ESA/Redu for their involvement in the data acquisition process. Sylvie Benck and Stanislav Borisov thank the Belgian Science Policy—Space Research and Applications (BELSPO) team for support to the PRODEX project entitled “PROBA‐V/EPT—Data Exploitation‐Extension,” ESA/PRODEX PEA N° C4000107617. They also thank ESA/ESTEC members for their continuous support throughout the EPT mission and ESA/ESOC members for funding the first EPT products development within the Space Weather program (SSA—ESC—P2 and –P3) and its development continuation within the frame of ESA Space Safety Program's network of space weather service development and pre‐operational activities (supported under ESA Contract 4000134036/21/D/MRP, the SWESNET project). The project 21GRD02 BIOSPHERE has received funding from the European Partnership on Metrology, co-financed by the European Union's Horizon Europe Research and Innovation Programme and by the Participating States. This research was supported by the International Space Science Institute (ISSI) in Bern, through ISSI International Team project #477 (Radiation Belt Physics From Top To Bottom: Combining Multipoint Satellite Observations And Data Assimilative Models To Determine The Interplay Between Sources And Losses). All authors are grateful to the PROBA-V/EPT teams at B.USOC and ESA/Redu for their involvement in the data acquisition process. Sylvie Benck and Stanislav Borisov thank the Belgian Science Policy—Space Research and Applications (BELSPO) team for support to the PRODEX project entitled “PROBA-V/EPT—Data Exploitation-Extension,” ESA/PRODEX PEA N° C4000107617. They also thank ESA/ESTEC members for their continuous support throughout the EPT mission and ESA/ESOC members for funding the first EPT products development within the Space Weather program (SSA—ESC—P2 and –P3) and its development continuation within the frame of ESA Space Safety Program's network of space weather service development and pre-operational activities (supported under ESA Contract 4000134036/21/D/MRP, the SWESNET project).

Funders	Funder number
Belgian Science Policy—Space Research and Applications	C4000107617
European Union's Horizon Europe Research and Innovation Programme
European Society of Anaesthesiology	4000134036/21/D/MRP
International Space Science Institute	SSA—ESC—P2

Keywords

energetic protons
geomagnetic storms
radiation belts
solar cycle
solar energetic particle events
south Atlantic Anomaly

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10.1029/2022JA031202

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title = "Proton Flux Variations During Solar Energetic Particle Events, Minimum and Maximum Solar Activity, and Splitting of the Proton Belt in the South Atlantic Anomaly",

abstract = "The analysis of the proton flux variations observed by the Energetic Particle Telescope (EPT) at energies >9.5 MeV from the launch of PROBA-V satellite on 7 May 2013 up to October 2022 shows an anti-correlation between the proton fluxes and the solar phase. At solar minimum, the fluxes are higher at low L corresponding to the northern border of the South Atlantic Anomaly (SAA). This solar cycle modulation of the inner belt is mainly due to losses by increased atmospheric interactions during solar maximum. Strong Solar Energetic Particle (SEP) events, like in January 2014, June 2015, and September 2017, inject energetic protons at high latitudes, but not in the inner belt where protons are trapped at long term at low L. Nevertheless, big geomagnetic storms, including those following SEP a few days after, can cause losses of protons at the outer border of the proton belt, due to magnetic field perturbations. A double peak in the proton belt is observed during long period of measurements only for the EPT channel of 9.5–13 MeV. The narrow gap between the two peaks in the inner belt is located around L = 2. This resembles to a splitting of the proton belt, separating the SAA into two different parts, North and South. The high-resolution measurements of PROBA-V/EPT allow the observation of small-scale structures that brings new elements to the understanding of the different source and loss mechanisms acting on the proton radiation belt at LEO.",

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AU - Benck, S.

AU - Botek, E.

AU - Borisov, S.

AU - Winant, A.

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N2 - The analysis of the proton flux variations observed by the Energetic Particle Telescope (EPT) at energies >9.5 MeV from the launch of PROBA-V satellite on 7 May 2013 up to October 2022 shows an anti-correlation between the proton fluxes and the solar phase. At solar minimum, the fluxes are higher at low L corresponding to the northern border of the South Atlantic Anomaly (SAA). This solar cycle modulation of the inner belt is mainly due to losses by increased atmospheric interactions during solar maximum. Strong Solar Energetic Particle (SEP) events, like in January 2014, June 2015, and September 2017, inject energetic protons at high latitudes, but not in the inner belt where protons are trapped at long term at low L. Nevertheless, big geomagnetic storms, including those following SEP a few days after, can cause losses of protons at the outer border of the proton belt, due to magnetic field perturbations. A double peak in the proton belt is observed during long period of measurements only for the EPT channel of 9.5–13 MeV. The narrow gap between the two peaks in the inner belt is located around L = 2. This resembles to a splitting of the proton belt, separating the SAA into two different parts, North and South. The high-resolution measurements of PROBA-V/EPT allow the observation of small-scale structures that brings new elements to the understanding of the different source and loss mechanisms acting on the proton radiation belt at LEO.

AB - The analysis of the proton flux variations observed by the Energetic Particle Telescope (EPT) at energies >9.5 MeV from the launch of PROBA-V satellite on 7 May 2013 up to October 2022 shows an anti-correlation between the proton fluxes and the solar phase. At solar minimum, the fluxes are higher at low L corresponding to the northern border of the South Atlantic Anomaly (SAA). This solar cycle modulation of the inner belt is mainly due to losses by increased atmospheric interactions during solar maximum. Strong Solar Energetic Particle (SEP) events, like in January 2014, June 2015, and September 2017, inject energetic protons at high latitudes, but not in the inner belt where protons are trapped at long term at low L. Nevertheless, big geomagnetic storms, including those following SEP a few days after, can cause losses of protons at the outer border of the proton belt, due to magnetic field perturbations. A double peak in the proton belt is observed during long period of measurements only for the EPT channel of 9.5–13 MeV. The narrow gap between the two peaks in the inner belt is located around L = 2. This resembles to a splitting of the proton belt, separating the SAA into two different parts, North and South. The high-resolution measurements of PROBA-V/EPT allow the observation of small-scale structures that brings new elements to the understanding of the different source and loss mechanisms acting on the proton radiation belt at LEO.

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KW - geomagnetic storms

KW - radiation belts

KW - solar cycle

KW - solar energetic particle events

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Proton Flux Variations During Solar Energetic Particle Events, Minimum and Maximum Solar Activity, and Splitting of the Proton Belt in the South Atlantic Anomaly

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