Variability of VTEC Gradient and TEC Rate Index Over Kisumu, Kenya During Selected Quiet and Storm Days of 2013 and 2014
American Journal of Astronomy and Astrophysics
Volume 7, Issue 4, December 2019, Pages: 67-72
Received: Oct. 30, 2019;
Accepted: Nov. 26, 2019;
Published: Dec. 4, 2019
Views 613 Downloads 153
Uluma Edward, Department of Physics, Masinde Muliro University of Science & Technology, Kakamega, Kenya
Ndinya Boniface, Department of Physics, Masinde Muliro University of Science & Technology, Kakamega, Kenya
Omondi George, Department of Physics and Materials Science, Maseno University, Maseno, Kenya
Vertical Total electron content (VTEC) gradient or rate of change of TEC (ROT) and total electron content (TEC) rate index or rate of change of TEC index (ROTI) can directly be estimated from receiver independent exchange (RINEX) data and can be used to estimate presence and intensity of ionospheric irregularities. In this paper we present results of the variation of ROT and ROTI over Kisumu, Kenya (Geomagnetic coordinates: 9.64°S, 108.59°E; Geographic coordinates: 0.02°S, 34.6°E) for both selected quiet and disturbed conditions between 1st January 2013 and 31st December 2014 using data derived from NovAtel GSV4004B SCINDA-GPS receiver at Kisumu as a step in establishing ionospheric irregularities over Kisumu, Kenya during a high solar activity period of solar cycle 24. ROT was calculated from filtered average daily VTEC data within intervals of 120 seconds while ROTI was computed over 4 minutes window from ROT. ROT and corresponding ROTI for the selected quiet and storm days were plotted against universal time (UT). The presence and intensity of irregularities on the selected quiet and storm days of the years 2013 and 2014 were determined by checking ROT fluctuations and the corresponding ROTI values from the plots. The obtained results showed increased fluctuation of ROT corresponding with large ROTI values after sunset. The selected storm days of the years 2013 and 2014 had higher ROTI values than the selected quiet days of the years 2013 and 2014. The higher ROTI values during the selected storm days may be attributed to the impact of geomagnetic storms brought about by several competing dynamics including Prompt penetration electric field (PPEF), disturbance dynamo electric field (DDEF) and reduction in electron density due to increased recombination rates. The high ROTI values after sunset were a manifestation of post-sunset plasma irregularities. The obtained results also showed a diurnal trend for ROT and ROTI where ROT increased steadily from 0.00UT to around 12:00UT before falling and having an increased fluctuation between 18:00UT and 20:00UT. This corresponded well with low ROTI values between 0:00UT and 16:00UT followed by high ROTI values between 18:00UT and 20:00UT. The diurnal variability of ROT might have resulted from variation of TEC and which was attributed to changes in the intensity of incoming solar radiation.
Variability of VTEC Gradient and TEC Rate Index Over Kisumu, Kenya During Selected Quiet and Storm Days of 2013 and 2014, American Journal of Astronomy and Astrophysics.
Vol. 7, No. 4,
2019, pp. 67-72.
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://dx.doi.org/10.5539/apr.v4n2p105.
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. Doi: 10.5539/apr.V6n.1p.19.
Kintner, P. M., Ledvina, B. M., De paula, (2007). GPS and ionospheric scintillations. Space Weather 5, S09003. https://doi.org/10.1029/2006SW000260.
Prikryl, P., Jayachandran, T., Mushini, S., Richardson, I. (2014). High-latitude GPS phase scintillation and cycle slips during high-speed solar wind streams and interplanetary coronal mass ejections: a superposed epoch analysis. Earth, planets space 66: 62, doi: 10.1186/1880-5981-66-62.
Woodman, R. F. and LaHoz, C. (1976). Radar observations of F region equatorial irregularities. J, Geophys. Res, 81, 5447.
Basu, Su, Basu, S. (1985). Equatorial scintillations: advances since ISEA-6. J. Atmos. Terr. phys. 47 (8), 753-768.
Muella, M. T. A. H., de Paula, E. R., Kantor, I. J., Rezende, L. F. G., Smorigo, P. RF. (2009). Occurrence and zonal drifts of small-scale ionospheric irregularities over an equatorial station during solar maximum-magnetic quiet and disturbed conditions. AdvSpace Res. 43, 957-1973.
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, doi: 10.1029/2007JA012605.
Blanc, M. and Richmomd A. D. (1980). The ionospheric disturbance dynamo. J Geophys Res 85: 1669-1686.
Abdu, M. A., de Paula, E. R., Batista, I. S., Reinish, B. W., Matsuoka, M. T., Carmago, P. O., Veliz, O., Denardini, C. M., Sobral J. H. A., Kherani, E. A., de Siquera, P. M. (2008). Abnormal evening vertical plasma drifts and effects on ESF and EIA over Brazil-South Atlantic sector during 30th October 2003 superstorm. J Geophys Res. 113: A07313. https://doi.org/1029/2007JAD12844.
de Siqueira Negreti, P. M., de Paula, E. R., Candido, C. M. N. (2017). Total electron content responses to HILDCAAs and geomagnetic storms over South America. Ann. Geophys., 35, 1309-1327, 2017. https://doi.org/10.5194/angeo-35-1309,2017.
Bhattacharrya, 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 eveolution of equatorial plasma bubbles. Journal of Geophysical Researc, space physics, 124, 2256-2270. https://doi.org/10.1029/2018JA02595.
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/105194, Angeo-24-1581-2006.
Azzouzi, I., Migoya-Orue, Y., Coisson, P., Amory Mazaudier, C., Fleury, R. and Radicella, S. M. (2016). Day to day variability of VTEC and ROTI in October 2012 with impact of high-speed solar wind stream on 13th October 2012. www.researchgate.net/publication/299470637.
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/10.1016/j.jastp.2018.11.007.
Pi, X, Mannucci, A. J., Lindquister, U. J. and HO, C. M. (1997). Monitoring of Global Ionospheric irreqularities using the worldwide GPS network. Geophys. Res. Lett, 24 (18), 2283-2286, 1997. Doi: 10.1029/97GLO2273.
Modi, R. P. and Iyer, K. N. (1989). IEC and slab thickness near the peak of equatorial anomaly during sunspot maximum and minimum. Indian Journal of Radio and space physics, 18, 23-26.
Bolaji, O. S., Adeniyi, J. O., Radicella, S. M. and Doherty, P. H. (2012). Variability of total electron content over an equatorial West African station during low solar activity, Radio Sci., 47, RS1001, https://doi.org/10.1029/2011RS004812.
Fejer, B. G., Scherlies, L. and De paula, E. R. (1999). J. Geophys. Res. 104,19859. https://dx.doi.org/10.1029/1999JA900271.
Meggs, R. W., Mitchell, C. N. and Honary, F. (2008). GPS Solut. 12, 281. https:/dx.doi.org/10.1007/sh10291-008-0090-3.
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.
Omondi, G., Ndinya, B. and Baki, P. (2014). A 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, ISSN 2349-782.
Nishida, A., Iwasaki, N. and Nadata, T. (1996). The origin of fluctuations in the equatorial electrojet: a new type of geomagnetic variation, Ann. Geophys., Res., Vol. 113, A05301.