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Variations in the Structure of the Equatorial Anomaly during the Summer Solstice according to the Interkosmos-19 Satellite

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Abstract—

Changes in the structure of the summer equatorial anomaly of electron density with local time and longitude at high solar activity are considered in detail according to topside sounding data from the Interkosmos-19 satellite. It is shown that the equatorial anomaly starts to develop from ~0800 LT, when the winter (southern) crest is formed. The summer (northern) crest is ~2 h behind in development. It is formed at the background of a low latitudinal foF2 maximum. In the daytime, the northern crest is ~3° farther from the geomagnetic equator than the southern one. The crest position changes greatly with longitude. A local maximum is observed in the development of the equatorial anomaly at 1400 LT. It is particularly pronounced in the Eastern Hemisphere. The foF2 value above the geomagnetic equator and anomaly intensity change with longitude at 1200–1400 LT according to the changes in the vertical plasma drift W. A local minimum is observed in the development of the equatorial anomaly at 1800 LT. The anomaly intensity then increases to a maximum 1.5–2.0 h after the evening peak in W. Longitudinal foF2 variations and the anomaly intensity in the interval 2000–2200 LT are also associated with W variations. The anomaly intensity decreases after the maximum, and the crests decrease in magnitude and move toward the equator. The foF2 maxima in the crest region of the anomaly after midnight, conversely, are farther away from the geomagnetic equator, which seems to be due to the action of the neutral wind. The equatorial anomaly has almost decayed by 0400 LT and does not manifest itself as a structure from 0500 to 0700 LT. Therefore, the well-expressed equatorial anomaly is observed from 1200 to 2400 LT at high solar activity.

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REFERENCES

  1. Appleton, E.V., Two anomalies in the ionosphere, Nature, 1946, vol. 157, p. 691.

    Article  Google Scholar 

  2. Balan, N. and Bailey, G.J., Equatorial plasma fountain and its effects: Possibility of an additional layer, J. Geophys. Res., 1995, vol. 100, no. 11, pp. 21 421–21 432. https://doi.org/10.1029/95JA01555

    Article  Google Scholar 

  3. Chen, Y., Liu, L., Le, H., Wan, W., and Zhang, H., Equatorial ionization anomaly in the low-latitude topside ionosphere: Local time evolution and longitudinal difference, J. Geophys. Res., 2016, vol. 121, pp. 7166–7182. https://doi.org/10.1002/2016JA022394

    Article  Google Scholar 

  4. Eccles, D. and King, J.W., A review of topside sounder studies of the equatorial ionosphere, Proc. IEEE, 1969, vol. 57, no. 6, pp. 1012–1018.

    Article  Google Scholar 

  5. Farelo, A.F., Herraiz, M., and Mikhailov, A., Global morphology of night-time NmF2 enhancements, Ann. Geophys., 2002, vol. 20, no. 11, pp. 1795–1806.

    Article  Google Scholar 

  6. Fejer, B.G., Jensen, J.W., and Su, S.-Y., Quiet time equatorial F region vertical plasma drift model derived from ROCSAT-1 observations, J. Geophys. Res., 2008, vol. 113, A05 304. https://doi.org/10.1029/2007JA012801

    Article  Google Scholar 

  7. Hopkins, H.D., Longitudinal variation of the equatorial anomaly, Planet. Space Sci., 1972, vol. 20, no. 12, pp. 2093–2098.

    Article  Google Scholar 

  8. Huang, Y.-N. and Cheng, K., Solar cycle variations of the equatorial ionospheric anomaly in total electron content in the Asian region, J. Geophys. Res., 1996, vol. 101, no. 11, pp. 24 513–24 520.

    Article  Google Scholar 

  9. Karpachev, A.T., Characteristics of the global longitudinal effect in a nighttime equatorial anomaly, Geomagn. Aeron., 1988, vol. 28, no. 1, pp. 46–49.

    Google Scholar 

  10. Karpachev, A.T., Diurnal and longitudinal variations of the structure of an equatorial anomaly during equinoxes according to Intercosmos-19 satellite data, Geomagn. Aeron. (Engl. Transl), 2018, vol. 58, no. 3, pp. 407–419.

  11. Karpachev, A.T. and Gasilov, N.A., Zonal and meridional wind components derived from Intercosmos-19 hmF2 measurements, Adv. Space Res., 2001, vol. 27, nos. 6–7, pp. 1245–1252.

    Article  Google Scholar 

  12. King, J.W., Olatunji, E.O., Eccles, D., and Newman, W.S., The integrated electron content in the equatorial ionosphere, J. Atmos. Terr. Phys., 1967, vol. 29, no. 11, pp. 1391–1396.

    Article  Google Scholar 

  13. Klimenko, V.V., Karpachev, A.T., Klimenko, M.V., Ratovskii, K.G., and Korenkova, N.A., Latitudinal structure of the longitudinal effect in the nighttime ionosphere during the summer and winter solstice, Russ. J. Phys. Chem. B., 2016, vol. 10, no. 1, pp. 91–99.

    Article  Google Scholar 

  14. Lei, J., Thayer, J.P., and Forbes, J.M., Longitudinal and geomagnetic activity modulation of the equatorial thermosphere anomaly, J. Geophys. Res., 2010, vol. 115, A08 311. https://doi.org/10.1029/2009JA015177

    Article  Google Scholar 

  15. Liu, H., Stolle, C., Forster, M., and Watanabe, S., Solar activity dependence of the electron density at 400 km at equatorial and low latitudes observed by CHAMP, J. Geophys. Res., 2007, vol. 112, A11 311. https://doi.org/10.1029/2007JA012616

    Article  Google Scholar 

  16. Liu, H. and Watanabe, S., Seasonal variation of the longitudinal structure of the equatorial ionosphere: Does it reflect tidal influences from below?, J. Geophys. Res., 2008, vol. 113, A08 315. https://doi.org/10.1029/2008JA013027

    Article  Google Scholar 

  17. Lockwood, G.E.K. and Nelms, G.L., Topside sounder observations of the equatorial anomaly in the 75° W longitude zone, J. Atmos. Terr. Phys., 1964, vol. 26, no. 5, pp. 569–580.

    Article  Google Scholar 

  18. Luan, X., Wang, P., Dou, X., and Liu, Y.C.-M., Interhemispheric asymmetry of the equatorial ionization anomaly in solstices observed by cosmic during 2007–2012, J. Geophys. Res., 2015, vol. 120, pp. 3059–3073. https://doi.org/10.1002/2014JA020820

    Article  Google Scholar 

  19. Lyon, A.J. and Thomas, L., The F2-region equatorial anomaly in the African, American and East Asian sectors during sunspot minimum, J. Atmos. Terr. Phys., 1963, vol. 25, no. 7, pp. 373–386.

    Article  Google Scholar 

  20. Matuura, N., Characteristics of global distribution of foF2, Sol. Terr. Environ. Res. Jpn., 1981, vol. 5, pp. 35–38.

    Google Scholar 

  21. Moffet, R., The equatorial anomaly in the electron distribution of the terrestrial F-region, Fundam. Cosmic Phys., 1979, vol. 4, pp. 313–391.

    Google Scholar 

  22. Pancheva, D. and Mukhtarov, P., Global response of the ionosphere to atmospheric tides forced from below: Recent progress based on satellite measurements global tidal response of the ionosphere, Space Sci. Rev., 2012, vol. 168, nos. 1–4, pp. 175–209.

    Article  Google Scholar 

  23. Rajaram, G., Structure of the equatorial F-region, topside and bottomside—a review, J. Atmos. Terr. Phys., 1977, vol. 39, no. 9, pp. 1125–1144.

    Article  Google Scholar 

  24. Ram, S.T., Su, S.-Y., and Liu, C.H., FORMOSAT-3/ COSMIC observations of seasonal and longitudinal variations of equatorial ionization anomaly and its interhemispheric asymmetry during the solar minimum period, J. Geophys. Res., 2009, vol. 114, A06 311. https://doi.org/10.1029/2008JA013880

    Article  Google Scholar 

  25. Rao, B.C.N., Some characteristic features of the equatorial ionosphere and the location of the F-region equator, J. Geophys. Res., 1963, vol. 68, no. 9, pp. 2541–2549.

    Article  Google Scholar 

  26. Rao, C.S.R. and Malthotra, P.L., A study of geomagnetic anomaly during I.G.Y, J. Atmos. Terr. Phys., 1964, vol. 26, no. 11, pp. 1075–1085.

    Article  Google Scholar 

  27. Rao, M.P. and Jogulu, C., Diurnal development of the equatorial anomaly in the topside ionosphere, Indian J. Radio Space Phys., 1979, vol. 8, pp. 310–317.

    Google Scholar 

  28. Rishbeth, H., The equatorial F-layer: Progress and puzzles, Ann. Geophys., 2000, vol. 18, no. 7, pp. 730–739.

    Article  Google Scholar 

  29. Rush, C.M., Rush, S.V., Lyons, L.R., and Venkateswaran, S.V., Equatorial anomaly during a period of declining solar activity, Radio Sci., 1969, vol. 4, no. 9, pp. 829–841.

    Article  Google Scholar 

  30. Sastri, J.H., Equatorial anomaly in F-region—a review, Indian J. Radio Space Phys., 1990, vol. 19, no. 4, pp. 225–240.

    Google Scholar 

  31. Sharma, R.P. and Hewens, E.J., A study of the equatorial anomaly at American longitudes during sunspot minimum, J. Atmos. Terr. Phys., 1976, vol. 38, no. 5, pp. 475–484.

    Article  Google Scholar 

  32. Thomas, L., The F2-region equatorial anomaly during solstice periods at sunspot maximum, J. Atmos. Terr. Phys., 1968, vol. 30, pp. 1631–1640.

    Article  Google Scholar 

  33. Walker, G.O., Longitudinal structure of the F-region equatorial anomaly—a review, J. Atmos. Terr. Phys., 1981, vol. 43, no. 8, pp. 763–774.

    Article  Google Scholar 

  34. Walker, G.O. and Chan, C.S., The diurnal variation of the equatorial anomaly in the topside ionosphere at sunspot maximum, J. Atmos. Terr. Phys., 1976, vol. 38, no. 7, pp. 699–706.

    Article  Google Scholar 

  35. Walker, G.O., Ma, J.H.K., and Golton, E., The equatorial ionospheric anomaly in electron content from solar minimum to solar maximum For South East Asia, Ann. Geophys., 1994, vol. 12, nos. 2–3, pp. 195–209.

    Article  Google Scholar 

  36. Xiong, C., Lühr, H., and Ma, S.Y., The magnitude and inter-hemispheric asymmetry of equatorial ionization anomaly-based on CHAMP and GRACE observations, J. Atmos. Sol.-Terr. Phys., 2013, vol. 105, pp. 160–169. https://doi.org/10.1016/j.jastp.2013.09.010

    Article  Google Scholar 

  37. Yizengaw, E., Moldwin, M.B., Sahai, Y., and Rodolfo, J., Strong postmidnight equatorial ionospheric anomaly observations during magnetically quiet periods, J. Geophys. Res., 2009, vol. 114, A12 308. https://doi.org/10.1029/2009JA014603

    Article  Google Scholar 

  38. Yue, X., Schreiner, W.S., Kuo, Y.-H., and Lei, J., Ionosphere equatorial ionization anomaly observed by GPS radio occultations during 2006–2014, J. Atmos. Terr. Phys., 2015, vol. 129, no. 7, pp. 30–40.

    Article  Google Scholar 

  39. Zeng, Z., Burns, A., Wang, W., Lei, J., Solomon, S., Syndergaard, S., Qian, L., and Kuo, Y.-H., Ionospheric annual asymmetry observed by the cosmic radio occultation measurements and simulated by the TIEGCM, J. Geophys. Res., 2007, vol. 113, A07 305. https://doi.org/10.1029/2007JA012897

    Article  Google Scholar 

  40. Zhao, B., Wan, W., Liu, L., and Ren, Z., Characteristics of the ionospheric total electron content of the equatorial ionization anomaly in the Asian–Australian region during 1996–2004, Ann. Geophys., 2009, vol. 27, no. 10, pp. 3861–3873.

    Article  Google Scholar 

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Funding

This work was supported by the Presidium of the Russian Academy of Sciences, project no. 28.

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  1. Institute of Terrestrial Magnetism, Ionosphere and Radio Wave Propagation, Moscow, Russia

    A. T. Karpachev

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Correspondence to A. T. Karpachev.

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Translated by O. Pismenov

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Karpachev, A.T. Variations in the Structure of the Equatorial Anomaly during the Summer Solstice according to the Interkosmos-19 Satellite. Geomagn. Aeron. 60, 224–235 (2020). https://doi.org/10.1134/S0016793220020061

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