ANALYSIS OF THE DAILY HOURLY DEPARTURES OF THE GEOMAGNETIC H FIELD OVER LOW-LATITUDE STATIONS

Abstract

The telecommunication technologies deployed in the last decades have shown that there are better days ahead. From electric telegraphs systems in the 19th century to today’s wireless communication using satellites and land links (Lanzerotti, 2001). The horizontal component (H-field) of the geomagnetic field has great impacts in the present-day communication technologies. The aim of this paper was to analyse the daily hourly departures of geomagnetic H-field along the low-latitude stations on the equatorial chain in relation to their correlation coefficients with their longitudes. The magnitude of H-component is a very significant factor in the determination of the total magnetic field of any location on the earth. The baseline values (H0) which is the average of H components at 23LT, 24LT, 1LT and 2LT were subtracted from the hourly values of H (Ht) to obtain the hourly departures of H (dH). The hourly departures of H (dH) from the baseline is non-cyclic since H1 ≠ H24 as observed over the three MAGDAS stations in Nigeria. The correlation coefficients between dHs of Lagos/Ilorin, Ilorin/Abuja and Abuja/Ilorin are 0.97, 0.75 and 0.66 respectively. This suggests that substorms are deflected eastwards along different longitudes due to the rotation of the earth such that locations in the same longitudes have the same hourly departures. There is no solar radiation during the nighttime, thus dH should be zero but for the energy stored in the magnetotail, the reduction of hourly departures towards nighttime in Nigeria is evident. This is further revealed as the midnight dH amplitudes decrease regularly. The eastward motion of the electrons during substorms was suggested to be responsible for the reduction of the H-field at the nightside magnetotail region for all the stations. These findings will assist the telecommunication companies to know which location is best for their transmitters to be sited in order to reduce loss of signals along the optical cables to the receivers. Furthermore, global telecomms companies should have business continuity plan which should include risk assessment and prompt response to geomagnetic disturbances being one of the causes for telecommunication outages.