Signature of Hale and Gleissberg solar cycles in the geomagnetic activity

Abstract

[1] The aa index, designed to describe the geomagnetic activity at global scale, has been shown to have increased in the twentieth century by about 65%. The increase in the case of a corrected aa is about 38%, similar to the ones of the recently introduced interhour variability (IHV) and interdiurnal variability (IDV) indices of geomagnetic activity. In terms of 11-year running averages, there is a long-term similarity between aa, R (the sunspot number), x, y, z, and r (geomagnetic indices designed to characterize the solar quiet daily variation, controlled by the solar UV radiation), and S (the solar irradiance). We show that the variation depicted by 11-year running averages of aa and R (and by consequence also of the other parameters mentioned) results from the superposition of Hale and Gleissberg cycle signatures in the corresponding time series. The IHV and IDV indices are included in the analysis. The two signals have a substantial contribution in R (10-30% and 20-34%, respectively, of the amplitude of the solar cycle 22) and aa (<12-27% and $30%, respectively, of the corresponding cycle 22 in aa). Characteristics of the two signals in the solar and geomagnetic activity and several implications of the geomagnetic activity and the solar quiet daily variation relationship with various solar outputs at the Hale and Gleissberg timescales are discussed.Citation: Demetrescu, C., and V. Dobrica (2008), Signature of Hale and Gleissberg solar cycles in the geomagnetic activity,

The correlation between solar and geomagnetic activity – Part 1: Two-term decomposition of geomagnetic activity

“…Geomagnetic activities can be resulted from variable current systems formed in the magnetosphere and ionosphere, such as the ring current and auroral ionospheric current, which are strongly modulated by solar activities via the interaction of the magnetosphere with solar winds (Feynman, 1980;Legrand and Simon, 1989a,b;Demetrescu and Dobrica, 2008) or others Simon, 1981, 1989a;Stamper et al, 1999;Tsurutani et al, 2006). It is believed that the geomagnetic activity is well associated with the solar wind speed (V ), the southward component (B z ) of the interplanetary magnetic field (IMF) and their product (Snyder et al, 1963;Russell and McPherron, 1973;Garrett et al, 1974;Crooker et al, 1977;Svalgaard, 1977;Feynman, 1980;Wang and Sheeley, 2009).…”

The Effects of Space Weather on Hurricane Activity

“…The aa geomagnetic index seems to present this periodicity (e.g. Cliver et al, 1996;Demetrescu and Dobrica, 2007), associated to a polarity reversal/geometrical coupling mechanism (Rosenberg and Coleman, 1969;Russell and McPherron, 1973) plus an intrinsic variation of the polar magnetic field of the Sun (Cliver et al, 1996). Climatic phenomena also present a 22 yrs cycle, for instance droughts (e.g.…”

“…This alternation is ultimately linked to the solar magnetic field and its changing polarity via the interaction with a relic constant magnetic field in the convection zone (e.g. Mursula et al, 2001;Prestes et al, 2006;Demetrescu and Dobrica, 2007). In CR the 22yrs cycle is associated to the inversion of the Sun's general magnetic field around the maximum of activity (Kota and Jokipii, 1983).…”

Geomagnetic response to solar and interplanetary disturbances

“…Within the frame of the COST Action, two papers have been published on the long-term behaviour of the solar/heliosphere/magnetosphere environment: Demetrescu & Dobrica (2008) and Demetrescu et al (2010). Annual means of measured and reconstructed solar, heliospheric and magnetospheric parameters were used to characterise the space climate through the long-term evolution of the relevant parameters, and to infer solar-activity signatures on the timescales of the Hale and Gleissberg cycles in the three environments.…”