Physics of auroral phenomena : proceedings of the 33rd Annual seminar, Apatity, 02 - 05 March, 2010 / [ed.: A.G. Yahnin, A. A. Mochalov]. - Апатиты : Издательство Кольского научного центра РАН, 2011. - 206 с. : ил.

L.A. Dremukhina at al. We have been analysed so called Sz-events (negative Sz-events - Bz ~events and positive ones - 5z+-events), having |Szl > 5 and duration т > 4 hours, using statistics o f 1967- 1984 and 1996 - 2004 from OMNI data set: http://omniweb.gsfc.nasa.gov. Sz-events and the solar activity during 1967 - 1984 It has been known that occurrence of Sz-events practically follows by the solar activity variation. But peak of Sz- events is wider and is extended over final phase o f the solar activity increasing and the starting phase o f the solar activity decreasing in the 11-year solar cycle. Sz-events occur mainly in the solar activity maximum that may be caused by non-stationary events on the Sun. Assignment o f the solar wind parameters in Sz-events during 1967 - 1987 such as module o f the IMF vector (S), density ( N) and velocity (V) o f the solar wind, and particle temperature (7) is demonstrated in Figure 1. Each panel shows total number o f Sz+-events and Sz'-events during the interval under study and expressed as percentage number of Sz+-events and Bz' -events within scale spacing corresponding to mentioned parameters. As can be seen, appreciable percent of Sz-events occurrence is fixed simultaneously with increasing, in comparison with mean, values of the solar wind parameters. Sz-events and the solar activity during 1996 - 2004 Using data of 1996 - 2004 we have examined and compared a) number of Sz-events; b) number of solar mass ejection events registered by SOHO spacecraft (SME-events); c) number o f solar mass ejection events directed towards the Earth and reaching it, so called interplanetary CME - (ISME-events). It has been shown annual variation of ISME-events number is similar to that o f number Sz-events. Maximum discrepancy is distinguished in 2002 when number of ISME-events decreases more sharply than number o f Sz- events. Annual variation of SME-events is similar to the same variation o f the solar activity. Little minimum peak in 1999 is exceptional case caused probably with error of narrow SME registration that occurred in this year. Little minimum peak of ISME-events and Sz-events is distinguished in 1999 as well. Thus, we can say that SME-events and Sz-events are typical ones when the solar activity is high. Number o f Sz- events correlates with number of events when the solar mass ejection reaches the Earth. Besides, number of Sz+- events is roughly equal to that o f Sz'-events. Maximum peak of Sz-event occurrences in Equinox As it is known, annual variation o f the geomagnetic activity has maximums in vernal and autumnal equinox. It should be possible to explain that modulation of IMF Bz component, transformed to the Solar Magnetospheric system coordinates (GSM), is caused by inclination of the Earth’s axis and the solar one to the ecliptic and inclination of magnetic dipole axis to the Earth rotation axis. According to this model vernal and autumnal GSM Bz - events number should be much larger than GSE one. (GSE is the Solar Ecliptic coordinate system). Using data of 1998-2002 we have computed average monthly number o f GSM Sz-events and GSE Sz-events. In spring and autumn GSM Sz-events are indeed rather more than GSE one, but in summer number of GSM Sz-events is roughly equal to that o f GSE Sz-events. When IMF vector components transform from GSE coordinates to GSM coordinates, negative GSM Bz amplitudes grows under sunward IMF sector structure in spring and under anti-sunward one in autumn. In other words IMF sector structure direction should increase or decrease as number of Sz+-events as number o f Bz' -events. We have computed average monthly differences of GSM Sz-event numbers and GSE Sz-event ones and differences average monthly GSM Sz-event numbers and GSE Sz-event ones normalized to number o f average daily values of IMF components causing IMF sector structure (sunward or anti-sunward). Maximum o f Sz-event numbers in April and September don’t depend on the solar activity or number of solar mass ejection events observed near the Earth. Its appearances should be explained by Russell and McPherron [1973] effect based on transformation of IMF vector components from GSE coordinates to GSM coordinates. Sz-events and geomagnetic activity Geomagnetic activity relationship with Sz-events was examined using data o f 2000 which is the solar activity maximum. We have chosen 46 storms with Kp > 5 or Dst <- 50 nT. For each storm we have found Bz' -events, and for specified Bz' -event we have calculated duration r, average Bz amplitudes, and average of the solar wind velocity (V). 56