Characterization of variability of Total Electron Content (TEC) over Malindi

Abstract

The dynamics of the ionosphere depends largely on solar activity. The attenuation of radio signals as they propagate through the ionosphere can be determined through a parameter called the Total Electron Content (TEC),which is a measure of the number of electrons along a line of sight. The variability of TEC is critical around the dip equatorial region especially within 15° North and South where we experience anomalously enhanced TEC in the ionosphere. This study focused on the characterization of the variability of TECover Malindi, Kenya (03.03°N, 40.13°E), and the variability studies were carried out using inter-quartile range as the parameter, with goal of coming up with a morphological description of TECthat would be useful in the understanding of the space weather conditions over Kenya. The objectives of the study were to obtain plots of TECagainst time for each day of the four months, January, April, July and October, representing four seasons, of the years 1999, 2000, 2001 and 2002 and to characterize the variability of the TEC during the period of study. The diurnal variability was greatest during the early morning and late evening hours of the local time and minimum during the midday and midnight. The seasonal variability was greatest during the March equinox, moderate during the summer equinox and least during the solstices. There was observed enhanced night-time variability just before midnight, which could be attributed to neutral winds. Of the four years studied, 2000 and 2001 experienced the highest level of TEC variability and a TECvariability level of between 12 and 30 TECU was thought to be significant enough to depict the occurrence of scintillations. The research findings would be useful to aviation industry, the marine industry, the communication service providers and other technological systems whose operations may be affected by the space weather conditions.