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The Atmospheric Electric Field (AEF) persists in fair weather regions, without local electrification processes and shows a daily variation with Universal Time independent of where the AEF was measured. This curve is generally known as the Carnegie Curve (Harrison, 2013) and is closely related to the current flowing in the Global Atmospheric Electric Circuit (GAEC).

The GAEC is formed between the Earth’s surface and the ionosphere. The atmosphere of the Earth is located between these two conducting layers. Electrical generators do exist below or inside electrified clouds to maintain the AEF, implying that an electrical current flows up to the ionosphere above these clouds. The electrical circuit is closed by downward currents flowing through the fair weather and semi-fair weather regions of the Earth’s atmosphere and through the rocks and oceans of the Earth´s surface (Rycroft et al., 2008).

The well-known and close correlation between the electrical generating system of the GAEC and the Carnegie curve has been extensively reported. However, the exact link is not well understood and continuous monitoring of the AEF is required in different geographical areas to help in the interpretation of the behavior of the GAEC. Solar and space weather phenomena affect the ionosphere causing disturbances in the GAEC, which can be monitored by analyzing the variations of the fair weather AEF. Transient variations of the intensity of the AEF have also been systematically reported in association with time fluctuations of the secondary cosmic ray flux measured at the same location (Raulin et al., 2014). The GAEC is also used to look for short-term precursors of seismic activity (Tacza et al., 2014). The purpose of the new Atmospheric Electric Field Network in South America (AFINSA) is to improve our understanding of these above questions.

References:

Tacza, J., Raulin, J.-P., Macotela, E., Marun, A., Fernandez, G., Bertoni, F.C.P., Lima, L.M., Samanes, J., Buleje, Y., Correia, E., Alves, G., Makita, K. Local and global effects on the diurnal variation of the atmospheric electric field in South America by comparison with the Carnegie curve. Atmospheric Research, 240, 2020.

Tacza, J., Raulin, J.-P., Macotela, E.L., Norabuena, E., Fernandez, G., Correia, E., Rycroft, M.J., Harrison, R.G. A new South American network to study the atmospheric electric field and its variations related to geophysical phenomena. J. Atmos. Sol. Terr. Phys. 120, 70–79, 2014.

Harrison,R.G.  The  Carnegie  Curve.  Surveys  in  Geophysics,  34,  2,  209-232, 2013.

Rycroft, M. J., Harrison, R. G., Nicoll, K. A. and Mareev, E. A. An overview of Earth’s global electric circuit and atmospheric conductivity. Space Science Reviews, 137 (1-4), 83-105, 2008.