Naslov
Four decades of geomagnetic and solar activity:1960-2001

Autori
Verbanac, Giuliana ; Vršnak, Bojan ; Temmer, Manuela ; Mandea, Mioara ; Korte, Monika

Vrsta, podvrsta i kategorija rada
Sažeci sa skupova, sažetak, ostalo

Izvornik
Abstract book - Heliophysical Phenomena and Earth's Enviroment / - , 2009, 21-21

Skup
Heliophysical Phenomena and Earth's Enviroment

Mjesto i datum
Šibenik, Hrvatska, 07.09.2009. - 13.09.2009

Vrsta sudjelovanja
Poster

Vrsta recenzije
Međunarodna recenzija

Ključne riječi
solar-terrestrial relationship, geomagnetic activity, solar activity

Sažetak
The solar-terrestrial relationship has been widely studied by means of space weather indices and various solar wind parameters. In this study we perform such an investigation over four decades (1960--2001) on the global scale, and for the first time on the regional scale as well. The variation s regarded as the remaining external field signal (thereafter RES) and present in the European observatory annual means of the Northward, X, magnetic component is used as an indicator of the regional geomagnetic activity and are investigated regarding different processes occurring on the Sun. In order to understand how various geomagnetic activity indices respond to the interplanetary disturbances during different periods of the solar cycIe, the annual means of the solar activity index, F10.7, and geomagnetic Ap and Dst indices, are studied. The indices are inherently complex since they incIude contributions from different solar phenomena. By studying the crosscorrelations we aim to distinguish between different generation mechanisms. The relationships between the solar parameter F10.7 and RES, Dst, Ap, characterized by high cross-correlation coefficients, suggest the possibility to evaluate the behaviour ofthese geomagnetic parameters on short timescale. We found finite time lags among the investigated parameters. Our study suggests a one year delay of both RES and Dst after F10.7. The Ap is clearly de1ayed for about two years with respect to F10.7 and about one year with respect to Dst and RES. This indicate that the Ap responds to the solar activity in a different manner than Dst and RES, which aredominated by the coronal mass ejections activity. On the other hand, it seems that Ap is more sensitive to the high--speed streams (HSS) and Alfvenic waves present in HSS. The existence of time lags gives us the possibility to forecastdifferent parameters. Irnportantly, the proposed forecasting procedure offers the possibility to reconstruct the F10.7 from the inferred geomagnetic activity for the epochs prior to solar activity monitoring. This study contributes to understanding some physical processes on the Sun that cause the perturbations in the near-Earth interplanetary space and consequently in the Earth's magnetic field. Moreover such investigations may provide a better insight into the time evolution of the open and closed solar magnetic field, and into long term changes in the solar activity with related physical processes.

Izvorni jezik
Engleski

Znanstvena područja
Fizika, Geofizika

POVEZANOST RADA