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dH/dt nT/min (Obs) AE nT (Obs) Dst nT(Obs) 120 100 4500 4000 3500 3000 2500 2000 1500 1000 500 0 450 400 350 300 250 200 150 100 50 0 80 60 40 20 Equation 16 Falayi and Beloff 1193 r = 0.980 R 2 = 0.961 0 0 20 40 60 80 100 120 dH/dt nT/min (Pred) Equation 17 r = 0.949 R 2 = 0.901 0 500 1000 1500 2000 2500 3000 3500 4000 4500 AE nT (Pred) Equation 18 r = 0.925 R 2 = 0.856 0 50 100 150 200 250 300 350 400 450 Dst nT (Pred) Fig. 5. Comparison between observed and predicted values of the correlation coefficient at St John. Figure 6 illustrates the comparison between observed and predicted values of the correlation coefficient at Addis Ababa. From equation (19/ Table 2d) a correlation coefficient of 0.859 exists between time derivatives of the horizontal geomagnetic field, the auroral electrojet and disturbance storm time. The coefficient of determination of 0.739 implies 73.9 % of time derivatives of the horizontal magnetic field can be accounted for by using the auroral electrojet and disturbance storm time. Addis Ababa dH/dt nT/min (Obs) dH/dt nT/min (Obs) 40 35 30 25 20 15 10 5 Equation 19 r = 0.859 R 2 = 0.7387 0 0 5 10 15 20 25 30 35 40 dH/dt nT/min (Pred) 40 35 30 25 20 15 10 5 Equation 20 r = 0.853 R 2 = 0.727 0 0 5 10 15 20 25 30 35 40 dH/dt nT/min (Pred) Fig. 6. Comparison between observed and predicted values of the correlation coefficient at Addis Ababa. Figure 7 shows the comparison between observed and predicted values of the correlation coefficient at Bangui. Equation (21/ Table 2e) shows a correlation coefficient of 0.952 that exists between time derivatives of the horizontal geomagnetic field, the auroral electrojet and disturbance storm time. The coefficient of determination of 0.907 implies 90.7% of time derivatives of the horizontal magnetic field can be accounted for by the using auroral electrojet and disturbance storm time. Bangui dH/dt nT/min ( Obs) 18 16 14 12 10 8 6 4 2 0 -2 Equation 21 r = 0.952 R 2 = 0.907 -2 0 2 4 6 8 10 12 14 16 18 dH/dt nT/min (Pred)
1194 dH/dt nT/min (Obs) 18 16 14 12 10 8 6 4 2 0 Equation 22 Canadian Journal of Pure and Applied Sciences r = 0.791 R 2 = 0.626 0 2 4 6 8 10 12 14 16 18 dH/dt nT/min (Pred) Fig. 7. Comparison between observed and predicted values of the correlation coefficient at Bangui. Figure 8 is devoted to the comparison between observed and predicted values of the correlation coefficient at Mbour. Equation (23/ Table 2f) shows a correlation coefficient of 0.917 that exists between time derivatives of the horizontal geomagnetic field, auroral electrojet and disturbance storm time. The coefficient of determination of 0.841 implies 84.1% of time derivatives of the horizontal magnetic field can be accounted for by using the auroral electrojet and disturbance storm time. M’bour dH/dt nT/min (Obs) dH/dt nT/min (Obs) 30 25 20 15 10 5 Equation 23 r = 0.917 R 2 = 0.8407 0 0 5 10 15 20 25 dH/dt nT/min (Pred) 30 25 20 15 10 5 Equation 24 r = 0.912 R 2 = 0.832 0 0 5 10 15 20 25 dH/dt nT/min (Pred) Fig. 8. Comparison between observed and predicted values of the correlation coefficient at Mbour. The statistical tests, RMSE and MBE were used to evaluate the accuracy of the predicted time derivatives of the geomagnetic fields. They provide the long and short term performances of an equation. The smaller the values, the better the equation. RESULTS AND DISCUSSION During geomagnetic activity periods, the amplitude of auroral electrojets flowing along the auroral oval increases and the auroral oval can extend toward and usually reach subauroral zones. Sometimes during very strong magnetic storms the auroral oval extends toward middle and equatorial latitudes, occasionally becoming visible from tropical latitudes. Many physical processes are involved in auroral zones: the precipitation of particles which increase the electric conductivities in the E region, the field aligned currents which close magnetospheric electric currents and the dawn dusk potential drop imposed by the solar wind flowing around the magnetosphere. All these processes contribute to an increase in the electric currents flowing in the ionosphere (Kikuchi et al., 1996; Abduet et al., 1998; Kobea et al., 1998). As the geomagnetic storm is intense the edge of the auroral boundary moves to a lower geographical latitude. Geomagnetic activity, even when there is not a big storm, affects the whole Earth from auroral to low latitudes. Kobea et al. (2000), shows the latitudinal profile of a magnetic disturbance observed on May 27, 1993 (Fig. 4 of the paper). The amplitude of this disturbance is ~ 150- 200nT at auroral latitudes ~ 80-100nT (half) at subauroral latitudes and still ~30nT at equatorial latitudes. Kappenman (1996, 2005) reported that the power grids are seriously affected by geomagnetic storms at high latitude due to large impulsive geomagnetic disturbance driven by auroral intensification, but there are signs that space weather poses significant risks to ground technology at low latitude (Addis Ababa) and subauroral latitudes (Ottawa and Victoria); it is reported in our investigation that when the rate of change of geomagnetic disturbance exceeded 30nT/min it posed a threat to power grids. Vanhamaki et al. (2005) established that changes in ionospheric current will give rise to induction current in the conducting ground which can significantly contribute to magnetic and electric fields. It has been reported that auroral electrojet, substorm onsets, geomagnetic pulsation and sudden impulses are responsible for large GIC (Boteler, 2001; Lam et al., 2002; Kappenman, 2003; Pulkkinen et al., 2003, 2005; Viljanen et al., 2006). Recently, Watari et al. (2009) confirmed that GIC associated with substorms were detected in Japan over a 2 year GIC measurement period, during the solar minimum although intense GIC do occur mostly during geomagnetic storms.
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EDITOR MZ Khan, SENRA Academic Publ
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SENRA Academic Publishers, Burnaby,
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Page 42 and 43: 1168 Prockop, DJ. 1964. Isotopic st
Page 44 and 45: 1170 copper(II) nitrate and zinc(II
Page 46 and 47: 1172 Infrared spectra The relevant
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Page 52 and 53: 1178 dimethyl-2H-indazol-6-yl)methy
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Page 56 and 57: 1182 The result of the mean interna
Page 58 and 59: 1184 Table 8. Histopathology result
Page 62 and 63: RMSE and MBE are statistical instru
Page 64 and 65: Figure 2 is similar to Figure 1, fo
Page 68 and 69: Tables 2 (a-f) contain summaries of
Page 70 and 71: Pulkkinen, A., Viljanen, A., Pajunp
Page 72 and 73: 1200 that a significant fraction of
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Page 86 and 87: 1214 Effect of supplementation of C
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