A new magnetic index based on the external part of vertical geomagnetic variations

• Autorzy: Ernst T. , Jankowski J. , Nowożyński K.
• Języki publikacji: EN

Abstrakty

EN

Variations of geomagnetic components X, Y, and Z recorded in 19 Intermagnet European observatories in 2004 were analysed. The original data from all observatories were preliminarily processed. In the first step, periods longer than three hours were filtered out. In the second step, variations of vertical geomagnetic component Z were separated into external and internal parts. We introduced a non-dimensional index η defined as the square root of a ratio of the energy of the external part of the vertical component to that of the horizontal components. Maps of the surface distribution of a new magnetic index η for the area of Europe at selected time periods were created, and their time changes are presented. The time changes of η for selected observatories are also shown. Moreover, we discuss a very interesting phenomenon we discovered, that has never been described in geophysical literature. Namely, in the recordings of all the observatories we noticed the presence of very regular variations, observed almost exclusively in the vertical component Z, which is quite unusual. These regular variations occur in the form of sinusoidal "wave packets". The amplitudes of these variations do not depend on the geomagnetic latitude and appear in the records of all the observatories we analyzed. They occur in quiet days, which suggests that their source is in the ionosphere.

Słowa kluczowe

EN

geomagnetic variations; ionosphere; magnetic activity; new magnetic index eta

• Wydawca: Instytut Geofizyki PAN ; Springer
• Czasopismo: Acta Geophysica
• Rocznik: 2010
• Tom: Vol. 58, no. 6
• Strony: 963--972
• Opis fizyczny: Bibliogr. 3 poz.

Twórcy

autor

Ernst T.

autor

Jankowski J.

autor

Nowożyński K.

• Institute of Geophysics, Polish Academy of Sciences, Warszawa, Poland,

Bibliografia

• Ernst, T., and J. Jankowski (2005), On the plane wave approximation of the external geomagnetic field in the regional induction study, Izvestiya, Physics Solid Earth 41, 5, 363-370.
• Parks, T.W., and J.H. McClellan (1972), Chebyshev approximation for nonrecursive digital filters with linear phase, IEEE Trans. Circuit Theory, CT-19, 189-194,
• Wielądek, R., and T. Ernst (1977), Application of the method of least squares to determining impulse responses and transfer functions, Publs. Inst. Geophys. Pol. Acad. Sc. G-1, 110, 3-12