Occurrence characteristics of equatorial plasma bubbles over Kisumu, Kenya during Solar maximum of Solar Cycle 24
Keywords:Equatorial Plasma Bubbles, Total Electron Content, Rate of Change of TEC, Rate of Change of TEC Index, Solar Cycle 24.
Equatorial Plasma Bubbles (EPBs) are irregular plasma density depletions in the ambient electron density in the equatorial F-region ionosphere generated after sunset. EPBs are known to bring disruptions to telecommunication and navigation systems. This paper investigates the occurrence of EPBs over Kisumu, Kenya (Geomagnetic coordinates: 9.64o S, 108.59o E; Geographic coordinates: 0.02o S, 34.6o E) for a few selected quiet and storm days between 1st January 2013 and 31st December 2014 which was a high Solar activity period for Solar Cycle 24. The study brings out EPB occurrence pattern over Kisumu, Kenya for the selected quiet and storm days of 2013 and 2014. The Receiver Independent Exchange (RINEX) data was retrieved from the Kisumu high data-rate NovAtel GSV4004B SCINDA-GPS receiver. The data was unzipped and processed to obtain Vertical Total Electron Content (VTEC), amplitude scintillation (S4) and Universal Time (UT) which were then fed into MATLAB to generate VTEC and S4 plots against UT for each selected quiet and storm day within the years 2013 and 2014. The Total Electron Content (TEC) depletion depths and S4 index values between 16:00 and 20:00 UT for each selected quiet and storm day were extracted from the VTEC and S4 plots and used to plot TEC depletion depths and S4 plots. The Rate of Change of TEC (ROT) and Rate of Change of TEC Index (ROTI) between 16:00 and 20:00 UT were generated from VTEC and used to plot ROT and the corresponding ROTI plots against UT. TEC depletion depths and ROTI values for each selected quiet and storm day between 16:00 and 20:00 UT were extracted and used to plot TEC depletion depths and ROTI plots and S4 index and ROTI plots. In this study, the enhancement of S4 index corresponded well with TEC depletions, increased fluctuation of ROT and higher ROTI values between 16:00UT and 20:00UT for most days. This correspondence was used in inferring the occurrence of EPBs during the selected quiet and storm days of the years 2013 and 2014. The obtained results showed that the highest EPB occurrence was during March equinox with 33.33% occurrence in the year 2013 and 30.76% occurrence in the year 2014, followed by the September equinox which had 20.38% occurrence in 2013 and 17.26% occurrence in 2014. The seasonal variation of EPB occurrence was attributed to the variation in the daytime E x B drift velocities. Larger E x B drift velocities resulted in increased EPB occurrence in the equinoctial period (March, April, August and September) and November solstice period (November and December) while lower E x B drift velocities resulted in reduced EPB occurrence in the June solstice period (June and July). The percentage EPB occurrence in the year 2013 was 6.49% while in the year 2014 was 4.32%. The storm period had percentage EPB occurrence of 21.42% in the year 2013 and 21.88% in the year 2014 while the quiet period had percentage EPB occurrence of 18.75% in the year 2013 and 7.89% in the year 2014. These results clearly showed that the percentage EPB occurrence was higher during the storm period than in the quiet period. Hence the development of EPBs was enhanced by geomagnetic activity through several competing dynamics such as Prompt Penetration Electric Field (PPEF), Disturbance Dynamo Electric Field (DDEF) and reduction in electron density due to increased recombination rates.
 Abdu, M., Bittencourt, J. and Batista, I. (1981). Magnetic declination control of the Equatorial F-region dynamo electric field development and spread F, J.Geophys. Res.-Space, 86, 11443-11446, 1981. https://doi.org/10.1029/JA086iA13p11443.
 Abdu, M. A., Batista, I. S., Takahashi, H, MacDougall, J., Sobral, J. H., Medeiros, A. F. and Trivedi B. (2003). Magnetospheric disturbance induced equatorial plasma bubble development and dynamics. A case study in Brazilian sector. Journal of Geophysical Research, 108(A12), 1449. https://doi.org/10.1029/2002JA009721.
 Abdu, M. A., Kherani, E. A., Batista, I. S. and Sobrai, J. H. A. (2009). Equatorial evening pre-reversal vertical and spread-F suppression by disturbance penetration electric field. Geophys Res Lett 36:119103. https://doi.org/10.1029/2009GL039919.
 Adetayo, V. E., Adewale, A. O., Akala, A. O., Bolaji, O. S. and Rabiu A. B. (2017). Studying the variability in the diurnal variations of GPS TEC over Nigeria.Ann. Geophys, 35,701-710, https://doi.org/10.5194/angeo-35-701-2017.
 Adewale A. O., Oyeyemi E. O., Adeloye A. B. , Mitchell C. N. , Rose J. A. R. and Cilliers P. (2012). A study of L-band scintillations and total electron content at an Equatorial Station. Lagos, Nigeria. Radio science, vol. 47, RS2011, https://doi.org/10.1029/2011RS004846.
 Basu, S., Basu, S., Rich, F. J., Grooves, K. M., Mackenzie, E., Coller, C., Sahai, Y., Fagundes, P. R. and Becker-Guedes, F. (2007). Response to the equatorial ionosphere at dusk to penetration electric fields during intense magnetic storms. J Geophys. Res, 112:A08308. https://doi.org/10.1029/2006JA012192.
 Barros, D.,Takahashi, H.,Wrasse, C. M. and Figueiredo C. A. O. B. (2018). Characteristics of Equatorial Plasma Bubbles observed by TEC map based on ground-based GNSS Receivers over South America. Ann. Geophys., 36,91-100,2018. https://doi.org/10.5194/angeo-36-91-2018.
 Battacharyya, A., Beach, T. L., Basu, S. and Kintner, P. M. (2000). Night-time equatorial ionosphere: GPS scintillations and differential carrier phase fluctuations, Radio Sci., 209-234. https://doi.org/10.1029/1999RS002213.
 Bhattacharyya, A., Fedrizzi, M., & Fuller-Rowell, T. J., Gurram, P.,Kakad, B., Sripathi, S. and Sunda, S. (2019). Effect of magnetic related storm thermospheric changes on evolution of equatorial plasma bubbles. Journal of Geophysical Research, space physics, 124, 2256-2270. https://doi.org/10.1029/2018JA025995.
 Batista, I., Medeiros, R. D., Abdu, M., Souza, J. D., Bailey, G. and Paula, E. D. (1996). Equatorial ionosphere vertical plasma drift model over Brazilian region, J. Geophys. Res.-Space, 101, 10887-10892, 1996. https://doi.org/10.1029/95JA03833.
 Beach, T. L., and P. M. Kintner (1999). Simultaneous Global positioning system observations of equatorial scintillations and total electron fluctuations. J. Geophys. 22, 553-22, 565, 1999. https://doi.org/10.1029/1999JA900220.
 Blanc, M. and Richmond, A. D. (1980).The ionospheric disturbance dynamo. J Geophys. Res, 85:1669-1686. https://doi.org/10.1029/JA085iA04p01669.
 Bolaji, O. S., Adebiyi, S. J. and Fashae J.B. (2019). Characterization of ionospheric irregularities at different longitudes during quiet and disturbed geomagnetic conditions. Journal of Atmospheric and Solar-terrestrial physics. https://doi.org/10.1029/2004JA010583.
 Caruana, P., Du, J., Wilkinson, P., Thomas, R. and Cervera, M. (2018). Determination of equatorial ionospheric scintillations S4 dual frequency GPS: Proceedings WARâ€™00: Workshop on applications of Radio Science, 27-29 April 2000, La Trobe University, pg. 85-90, http://www.ips.gov.au/IPS Hosted/NCRS/wars/wars2000.index.htm
 Cherniak, I., Zakharenkova, I. and Sokolvsky, S. (2019). Multi-instrumental observation of storm induced ionospheric plasma bubbles at equatorial and middle latitudes. Journal of research. Space physics.124, 1497-1508. https://doi.org/10.1029/2018JA026309.
 DasGupta, A., Paul, A. and Das, A.(2007). Ionospheric Total Electron Content (TEC) studies with GPS in the Equatorial region. PACs No.94.20.YX;94.20.VV.94.20.WW, 2007
 Eastwood, J. P., Biffis, E., Hapgood, M. A., Green, L., Bisi, M. M., Bentley, R. D., Wicks, R.,Mckinell, L. A., Gobbs, M. and Burnett, C. (2017). The economic impact of space weather:Where do we stand?Risk analysis.Vol. 37, No.2, 2017Doi:10.1111/risa.12765
 Fayose, R.S., Oladosu, O.R., Rabiu, A.B. and Grooves, K. (2012).Variation of Total Electron Content [TEC] and their Effect on GNSS over Akure,Nigeria. doi:10.5539/apr.v4n2p105. https://doi.org/10.5539/apr.v4n2p105.
 Fejer, B. G., Scherliess, L., de Paula, E. R. (1999). Effects of the vertical plasma drift velocity on the generation and evolution of equatorial spread F. Journal of Geophy. Res, vol 104, No. A9, 859-19, 869. https://doi.org/10.1029/1999JA900271.
 Fejer, B. G., Jensen, J. W. and Su, S. Y. (2008). Seasonal and longitudinal dependence of equatorial disturbance vertical plasma drifts, Geophys. Res. Lett., vol. 35, L20106. https://doi.org/10.1029/2008GL035584.
 Huang, C.,Burke, W., Machuzak, J., Gentile, L. and Sultan, P. (2002). Equatorial plasma bubbles observed by DMSP satellites during a full solar cycle: Towards a global climatology, J.Geophys. Res. space, 107, https://doi.org/10.1029/2002JA009452.
 Huang, C. Y., Burke, W. J., Ma Chuzak, J. S. and Gentile, L. C. and Sultan, P. J. (2001). DMSP Observations of equatorial plasma bubbles in the topside ionosphere near solar maximum. Journal of Geophysical Research, vol.106, No.A5, pg 8131-8142. https://doi.org/10.1029/2000JA000319.
 Kelley, M. C., Fejer, B. G. and Gonzales, C. A. (1979). An explanation from anomalous equatorial ionospheric fields associated with a northward turning of the interplanetary magneticfield.Geophys.ResLett6:301-304. https://doi.org/10.1029/GL006i004p00301.
 Kelley, M. C., Rodrigues, G. S., Makela, J. J., Tsunoda, R., Roddy, P. A., Retterer, J. M., de La Beaujardiere, O., de Paula, E. R. and Ilma, R. R. (2009). C/NOFS and radar observations during consecutive ionospheric storm event over South America. Geophys. Res.Lett., 36, L00c07, https://doi.org/10.1029/2009GL039378.
 Kikuchi, T., Hashimoto, K. K. and Nozaki, K. (2008). Penetration of magnetospheric electric fields to the equator during a geomagnetic storm. J Geophys. Res 113.a06214. https://doi.org/10.1029/2007JA012628.
 Kil, H. and Paxton, L. J. (2006). Ionospheric disturbances during the magnetic storm of 15th July 2000: Role of the fountain effect and plasma bubbles for the formation of large equatorial plasma density depletions. JGeophys.Res.111.A1231, https://doi.org/10.1029/2006JA011742.
 Jacobsen, K. S. (2014). The impact of different sampling rates and calculation time intervals on ROTI values. Jspace weather space Clim., 4, A33(2014). https://doi.org/10.1051/swsc/2014031.
 Li, G., Ning, B., Wan, W. and Zhao, B.(2006). Observations of GPS ionospheric scintillations over Wuhan during geomagnetic storms. Ann Geophys 24:1581-1590. https://doi.org/10.5194/angeo-24-1581-2006.
 Magdaleno, S., Herraiz M., Altadill, D. and De la Morena. (2017). Climatology characterization of equatorial plasma bubbles using GPS data. .J.Space Weather Space Clim,7 A3 (2017). https://doi.org/10.1051/swsc/2016039.
 Milos, M. (2014). Determination of TEC in the ionosphere using GPS Technology. Vol. 2, No. 2, https://doi.org/10.5194/angeo-22-3109-2004.
 Makela, J. J., Ledvina, B. M., Kelley, M. C. and Kintner, P. M. (2004). Analysis of seasonal variation of Equatorial plasma bubbles occurrence observed from Haleakala, Hawaii. Annales Geophysica (2004) 22:3109-3121.SRef-ID: 1432-0576/ag/2004-3109.
 Mukabana, J. R. and Pielke, R. A. (1996). Investigating the influence of synoptic-scale monsoonal winds and mesoscale circulations on Diurnal weather patterns Over Kenya using numerical model, American Meteorological Society, Monthly Weather Review, Vol 124.
 Mukherjee, S., Sarkar, S., Purohit, P. K., and Gwal, A. K. (2010). Seasonal variation of Total Electron Content at crest of equatorial anomaly station during low solar activity conditions, Adv. Spac Res., 46, 291-295, 2010. https://doi.org/10.1016/j.asr.2010.03.024.
 Nakata, H., Takahashi A., Takano T., Jaito A. and Sakanoi T. (2018). Observation of equatorial plasma bubbles by airglow imager on ISS-IMAP. Earth and planetary science. https://doi.org/10.1186/s40645-018-0227-0.
 Ndeda, O. H., and Odera, P. O. (2014). Analysis of Longitudinal Advancement of the peak Total Electron Content in the African equatorial anomaly region using data from GPS receivers and GIS stations in Kenya, Canadian Centre of Sc. & Educ. Applied Phys. Research: vol. 6, No. 1; 2014. https://doi.org/10.5539/apr.v6n1p19.
 Nishioka, M., Saito, A., Takano T. and Tsugawa T. (2008). Occurrence characteristics of plasma derived from global-ground based GPS receiver networks. J.Geophys, Res., 113,A05301, https://doi.org/10.1029/2007JA012605.
 Olwendo, J. O., Cilliers, P. J., Baki, P. and Mito, C. (2012). Using GPS-SCINDA observations to study the correlation between scintillation, total electron content enhancement and depletions over the Kenyan region: Advances in Space Research 49 (2012) 1363â€“1372. https://doi.org/10.1016/j.asr.2012.02.006.
 Omondi, G., Ndinya, B. and Baki, P. (2014). Study of the Equatorial ionosphere over Nairobi during selected magnetically disturbed and quiet times for the year 2009 using co-located instruments. IJARPS, Vol 1, 18-26, 2014.
 Omondi, G. E., Baki, P., Ndinya, B. O. (2019). Total electron content and scintillations over Maseno, Kenya during high solar activity year. Acta Geophysica. https://doi.org/10.1007/s11600-019-00354-7.
 Otsuka, Y., Shiokawa, K. and Ogawa, T. (2006). Equatorial Ionospheric scintillations and Zonal irregularity Drifts observed with closely Spaced GPS receivers in Indonesia. Journal of the Meteorological Society of Japan, Vol 84A, pp 343-351, 2006.
 Paznukhov, V. V., Carrano C. S., Doherty P. H., Grooves K. M., Caton R. G., Valladares C.E., Seemala G.K., Bridgwood C.T., Adenyi J., Ameshi L.L.N., Damtie B., Dujanga F.D., Ndeda J.O.H., Baki P.,Obrou O.K., Okere B. and Tsidu G. M. (2012). Equatorial plasma bubbles and L-band scintillations in Africa during solar minimum: Annales Geophysica, 30, 675â€“682, 2012. https://doi.org/10.5194/angeo-30-675-2012.
 Pi, X, Mannucci, A. J., Lindquister, U. J. and HO, C. M. (1997). Monitoring of Global Ionospheric irregularities using the worldwide GPS network. Geophys. Res. Lett, 24 (18), 2283-2286, 1997. https://doi.org/10.1029/97GL02273.
 Radicella, S. (2012). Workshop on science applications of GNSS in developing countries (11-27 April) followed by the Seminar on Development and use of ionospheric Ne Quick model 30th April -1st May 2012.
 Richmond, A. D., Peymirat, C. and Roble, R. G. (2003). Long-lasting disturbances in the equatorial ionospheric electric field simulated with a coupled magnetosphere-ionosphere thermosphere model. JGeophysRes108.1118. https://doi.org/10.1029/ 2002JA009758.
 Sahai, Y., Fagundes, P. and Bittencourt, J. (2000). Trans-equatorial F-region ionospheric plasma bubbles: Solar cycle effects, J. Atmos. Sol. Terr. Phys., 62, 1377-1383, 2000. https://doi.org/10.1016/S1364-6826(00)00179-6.
 Wang, C., Shi, C., Fan, L. and Zhang, H. (2018). Improved modeling of Global Ionospheric Total Electron content using prior information. Remote sens2018, 10, 63 https://doi.org/10.3390/rs10010063.
 Zernov, N. N., Gherm, V. E. and Strangeways H. J. (2009). On the effects of scintillation of low-latitude bubbles on trans-ionospheric paths of propagation, Radio Sci., 44, https://doi.org/10.1029/2008RS004074.
 Zou, Y. and Wang, D. (2009). A study of GPS ionospheric scintillations observed at Guilin, J. Amis. Sol. Terr.Phys., 71, 1948-1958, https://doi.org/10.1016/j.jastp.2009.08.005.