DAYSIDE AURORAL ACTIVITY DEPENDENCE FROM SOLAR WIND PARAMETERS

摘要

We report preliminary results from a statistical analysis on the relationship between the dayside (cusp) auroral activity and key parameters of the solar wind at Earth (velocity, pressure, magnetic field, etc.). The present study covers the 2003-2004 and 2004-2005 winter seasons, consisting of about three months each. Data collected by the ITACA2 auroral monitor (IFSI/INAF), located at the Italian Arctic base (Dirigibile Italia, Ny-Alesund, Sval-bard), were used in this study. Our statistical approach is based on the analysis of the 630.0 nm keograms (magnetic latitude vs. time plots) between 04:00-13:00 UT, that is, a window of eight-hours centered on the local magnetic noon (～ 09:00 UT), where the probability to observe the transit of the geomagnetic cusp is the highest. The solar wind conditions were derived from the ACE, WIND and GEOTAIL satellite data. It was also studied how the dayside auroral activity is directly influenced by the impact of interplanetary perturbations, linked to solar transient phenomena, as coronal mass ejections (CME), on the dayside magnetosphere. Halo or partial halo CME events were selected from the on-line catalogue (NASA/GSFC, http://cdaw.gsfc.nasa.gov/CMEJist/) derived by the LASCO coronograph dataset. The cosmic ray data recorded by the SVIRCO station (IFSI -UniRoma3) was used to help in identifying the interplanetary perturbation at the Earth's orbit (Forbush decrease).