Москва, Россия
Факультет космических наук и инженерии, Национальный Центральный Университет, Тайвань
Москва, Россия
We present the results of a statistical study of transient enhancements of electrons with energies >30 keV at low drift shells in the quasi-trapped region (forbidden zone) at the geomagnetic equator. Using data from low-altitude NOAA/POES and MetOp satellites, we have compiled a catalog of events with forbidden energetic electron (FEE) enhancements for the period from 1998 to 2023. Statistical analysis of FEE events has revealed solar-cyclic, as well as seasonal and diurnal variations in the occurrence of FEE enhancements. We have examined the correlation of the annual frequency of FEE events with solar activity, solar wind parameters, and geomagnetic activity. Strong correlations have been found with the F10.7 index of solar activity (radio emission flux) as well as with the Alfvén Mach number (solar wind parameter). An interpretation of the obtained results is proposed which is based on the mechanism of electrical drift and radial transport of electrons from Earth’s inner radiation belt to the quasi-trapped region (L<1.2). The key factor for the operation of the mechanism is the effective penetration of the electric field to low latitudes when a significant difference in the conductivity of the high-latitude ionosphere occurs in the illuminated and unilluminated sectors of local time under conditions of weakening auroral activity.
inner radiation belt, quasi-trapped electrons, solar-terrestrial relationships
1. Asikainen T., Mursula K. Filling the South Atlantic anomaly by energetic electrons during a great magnetic storm. Geophys. Res. Lett. 2005, vol. 32, L16102. DOI:https://doi.org/10.1029/2005GL023634.
2. Borovsky J.E., Birn J. The solar wind electric field does not control the dayside reconnection rate. J. Geophys. Res.: Space Phys. 2014, vol. 119, pp. 751–760. DOI:https://doi.org/10.1002/2013JA019193.
3. Borovsky J.E., Yakymenko K. Substorm occurrence rates, substorm recurrence times, and solar wind structure. J. Geophys. Res.: Space Phys. 2017, vol. 122, pp. 2973–2998. DOI:https://doi.org/10.1002/2016JA023625.
4. Clette F. Is the F10.7cm — sunspot number relation linear and stable? J. Space Weather Space Clim. 2021, vol. 11, iss. 5, art. 2. DOI:https://doi.org/10.1051/swsc/2020071.
5. Dmitriev A.V., Yeh H.-C. Storm-time ionization enhancements at the topside low-latitude ionosphere. Ann. Geophys. 2008, vol. 26, pp. 867–876.
6. Evans D.S. Dramatic increases in the flux of >30 keV electrons at very low L-values in the onset of large geomagnetic storms. EOS Trans. 1988, vol. 69, iss. 44, pp. 1393.
7. Evans D.S., Greer M.S. Polar Orbiting Environmental Satellite Space Environment Monitor – 2: Instrument descriptions and archive data documentation. 2006. available from NGDC: http://ngdc.noaa.gov/stp/satellite/poes/documentation.html (accessed April 25, 2024).
8. Golubkov M.G., Suvorova A.V., Dmitriev A.V., et al. Statistical analysis of decreases in energetic electron fluxes in low-latitude ionosphere from NOAA/POES and MetOp 1998–2022 data. Russian J. Physical Chemistry B: Focus on Physics. 2024, vol. 43. (In print).
9. Gusev A., Kohno T., Martin I., Pugacheva G.I., Turtelli A. Jr., Tylka A.J., Kudela K. Injection and fast radial diffusion of energetic electrons into the inner magnetosphere. Planet. Space Sci. 1995, vol. 43, pp. 1131–1134.
10. Heikkila W.J. Soft particle fluxes near the equator. J. Geophys. Res. 1971, vol. 76, pp. 1076–1078.
11. Hua M., Li W., Ma Q., Binbin Ni1, Nishimura Y., Shen Xiao‐Chen, Li H. Modeling the electron enhancement and butterfly pitch angle distributions on L shells <2.5. Geophys. Res. Lett. 2019, vol. 46, pp. 10967–10976. DOI:https://doi.org/10.1029/2019GL084822.
12. Hui D., Vichare G. Variable responses of equatorial ionosphere during undershielding and overshielding conditions. J. Geophys. Res.: Space Phys. 2019, vol. 124, pp. 1328–1342. DOI:https://doi.org/10.1029/2018JA025999.
13. Imhof W.L., Gaines E.E., Reagan J.B. Dynamic variations in intensity and energy spectra of electrons in the inner radiation belt. J. Geophys. Res. 1973, vol. 78, pp. 4568–4576. DOI:https://doi.org/10.1029/ja078i022p04568.
14. Kudela K., Matisin J., Shuiskaya F.K., Akentieva O.S., Romantsova T.V., Venkatesan D. Inner zone electron peaks observed by the “Active” satellite. J. Geophys. Res. 1992, vol. 97, pp. 8681–8683.
15. Lejosne S., Mozer F.S. Typical values of the electric drift E×B/B2 in the inner radiation belt and slot region as determined from Van Allen Probe measurements. J. Geophys. Res.: Space Phys. 2016, vol. 121, pp. 12014–12024. DOI: 10.1002/ 2016JA023613.
16. Lejosne S., Fedrizzi M., Maruyama N., Selesnick R.S. Thermospheric neutral winds as the cause of drift shell distortion in Earth’s inner belt. Front. Astron. Space Sci. 2021, vol 8, art. 725800. DOI:https://doi.org/10.3389/fspas.2021.725800.
17. Lejosne S., Fejer B., Maruyama N., Scherliess L. Radial transport of energetic electrons as determined from the “zebra stripes” measured in the Earth’s inner belt and slot region. Front. Astron. Space Sci. 2022, vol. 9, art. 823695. DOI:https://doi.org/10.3389/fspas.2022.823695.
18. Liu L., Chen Y. Statistical analysis of solar activity variations of total electron content derived at Jet Propulsion Laboratory from GPS observations. J. Geophys. Res.: Space Phys. 2009, vol. 114, A10311. DOI:https://doi.org/10.1029/2009JA014533.
19. Paulikas G.A. Precipitation of particles at low and middle latitudes. Rev. Geophys. Space Phys. 1975, vol. 13, iss. 5, pp. 709–734.
20. Pinto O., Pinto R.C.A., Gonzalez W.D., Gonzalez A.L.C About the origin of peaks in the spectrum of inner belt electrons. J. Geophys. Res. 1991, vol. 96, pp. 1857–1860. DOI:https://doi.org/10.1029/90JA02383.
21. Sauvaud J.A., Moreau T., Maggiolo R., Treilhou J.-P. High-energy electron detection onboard DEMETER: The IDP spectrometer description and first results on the inner belt. Planet. Space Sci. 2006, vol. 54, pp. 502–511.
22. Savenko I.A., Shavrin P.I., Pisarenko N.F. Low-energy particles at heights of 320 km and at near-equator latitudes. Iskusstvennye sputniki Zemli [Artificial Earth Satellites]. 1962, no. 3, pp. 75–80. (In Russian).
23. Selesnick R.S., Su Y.-J., Blake J.B. Control of the innermost electron radiation belt by large-scale electric fields. J. Geophys. Res.: Space Phys. 2016, vol. 121, pp. 8417–8427. DOI:https://doi.org/10.1002/2016JA022973.
24. Selesnick R.S., Su Y.-J., Sauvaud J.A. Energetic electrons below the inner radiation belt. J. Geophys. Res.: Space Phys. 2019, vol. 124, pp. 5421–5440. DOI:https://doi.org/10.1029/2019JA026718.
25. Su Y.-J., Selesnick R.S., Blake J.B. Formation of the inner electron radiation belt by enhanced large-scale electric fields. J. Geophys. Res.: Space Phys. 2016, vol. 121, pp. 8508–8522. DOI:https://doi.org/10.1002/2016JA022881.
26. Sun W., Yang J., Wang W., Cui J., Toffoletto F., Yue C., et al. Archimedean spiral distribution of energetic particles in Earth’s inner radiation belt. Geophys. Res. Lett. 2024, vol. 51, e2023GL106859. DOI:https://doi.org/10.1029/2023GL106859.
27. Suvorova A.V. Flux enhancements of >30 keV electrons at low drift shells L<1.2 during last solar cycles. J. Geophys Res.: Space Phys. 2017, vol. 122, pp. 12274–12287. DOI: 10.1002/ 2017JA024556.
28. Suvorova A.V., Dmitriev A.V. Radiation aspects of geomagnetic storm impact below the radiation belt. Cyclonic and Geo-magnetic Storms: Predicting Factors, Formation and Environmental Impacts. New York: NOVA Science Publishers, 2015, pp. 19–76.
29. Suvorova A.V., Tsai L.C., Dmitriev A.V. On relation between mid-latitude ionospheric ionization and quasi-trapped energetic electrons during 15 December 2006 magnetic storm. Planet. Space Sci. 2012, vol. 60, pp. 363–369. DOI: 10.1016/ j.pss.2011.11.001.
30. Suvorova A.V., Dmitriev A.V., Tsai L.-C., Kunitsyn V.E., Andreeva, E.S. Nesterov I.A., Lazutin L.L. TEC evidence for near-equatorial energy deposition by 30 keV electrons in the topside ionosphere. J. Geophys. Res. 2013, vol. 118, pp. 4672–4695. DOI:https://doi.org/10.1002/jgra.50439.
31. Suvorova A.V., Huang C.-M., Matsumoto H., Dmitriev A.V., Kunitsyn V.E., Andreeva E.S., et al. Low-latitude ionospheric effects of energetic electrons during a recurrent magnetic storm. J. Geophys. Res.: Space Phys. 2014, vol. 119, pp. 9283–9302. DOI:https://doi.org/10.1002/2014JA020349.
32. Suvorova A.V., Dmitriev A.V., Parkhomov V.A., Tsegmed B. Quiet time structured Pc1 waves generated during transient foreshock. J. Geophys Res.: Space Phys. 2019, vol. 124, pp. 9075–9093. DOI:https://doi.org/10.1029/2019JA026936.
33. Tadokoro H., Tsuchiya F., Miyoshi Y., Misawa H., Morioka A., Evans D.S. Electron flux enhancement in the inner radiation belt during moderate magnetic storms. Ann. Geophys. 2007, vol. 25, pp. 1359–1364.
34. Takagi S., Nakamura T., Kohno T., Shiono N., Makino F. Observation of space radiation environment with EXOS-D. IEEE Trans. Nucl. Sci. 1993, vol. 40, iss. 6, pp. 1491–1497.
35. Tanaka Y., Nishino M., Iwata A. Magnetic storm-related energetic electrons and magnetospheric electric fields penetrating into the low-latitude magnetosphere (L~1.5). Planet. Space Sci. 1990, vol. 38, iss. 8, pp. 1051–1059.
36. URL: https://omniweb.gsfc.nasa.gov/ (accessed April 25, 2024).
37. URL: https://ngdc.noaa.gov/stp/satellite/poes/dataaccess (accessed April 25, 2024).
38. URL: https://wdc.kugi.kyoto-u.ac.jp/aeasy/index.html (accessed April 25, 2024).
