Study of the solar wind coupling to the time difference horizontal geomagnetic field

P. Wintoft (1)

1 IRF - Swedish Institute of Space Physics [Kiruna]

The local ground geomagnetic field fluctuations (? B) are dominated by high frequencies and 83% of the power is located at periods of 32 min or less. By forming 10-min root-mean-square (RMS) of ? B a major part of this variation is captured. Using measured geomagnetic induced currents (GIC), from a power grid transformer in Southern Sweden, it is shown that the 10-min standard deviation GIC may be computed from a linear model using the RMS ? X and ? Y at Brorfelde (BFE: 11.67° E, 55.63° N), Denmark, and Uppsala (UPS: 17.35° E, 59.90° N), Sweden, with a correlation of 0.926±0.015. From recurrent neural network models, that are driven by solar wind data, it is shown that the log RMS ? X and ? Y at the two locations may be predicted up to 30 min in advance with a correlation close to 0.8: 0.78±0.02 for both directions at BFE; 0.81±0.02 and 0.80±0.02 in the X- and Y-directions, respectively, at UPS. The most important inputs to the models are the 10-min averages of the solar wind magnetic field component B_z and velocity V, and the 10-min standard deviation of the proton number density ?_n. The average proton number density n has no influence.

Keywords. Magnetospheric physics (Solar wind - magnetosphere interactions) ? Geomagnetism and paleomagnetism (Rapid time variations)

Domaines: Océan, Atmosphère; Sciences de la Terre

P. Wintoft. Study of the solar wind coupling to the time difference horizontal geomagnetic field. Annales Geophysicae, 2005, 23 (5), pp.1949-1957. ⟨hal-00317841⟩