Geoeffectiveness of Solar and Interplanetary Events Yuri I. Yermolaev, Michail Yu. Yermolaev, Georgy N. Zastenker, Anatoli A. Petrukovich, Lev M. Zelenyi Space Research Institute (IKI - ), RAS, Moscow, Russia Several results have been published and may be found in Report for International symposium “ Solar Extreme Events: Fundamental Science and Applied Aspects (SEE-2005)” Nor Ambert, Armenia, September 2005

1.Motivation of study 2.Data description 3.General characteristics of the period 4.Comparison of magnetic storms with solar sources 5.Comparison of storms with interplanetary sources 6.Discussion of results and conclusions Content

General concept of storm effectiveness of solar and interplanetary events

Motivation of study In the literature on the solar-terrestrial relations there are different estimations of storm effectiveness of solar and interplanetary events - from 30 up to 100%. The reasons of these discrepancies may be differences in used methods of (1) magnetic storm identification, (2) interplanetary space event identification, (3) solar event identification, and (4) correlation between geomagnetic, interplanetary and solar events. The aim of our report is - to make own analysis of data - to compare different methods of solar-terrestrial physics - to explain exiting discrepancies in published results.

Data description 1. List of strong solar flares (with X-ray importance equal and higher M5 ftp://ftp.ngdc.noaa.gov/STP/SOLAR_DATA/SOLAR_FLARES/XRAY_FLA RES ), 2. Parameters of solar wind and IMF ( + Prognoz 7-11 data), 3. Hour-average values of Dst index ( and 4. List of published results on CME observations and SOHO/Lasco list of halo CME for interval ( Data description

Solar, interplanetary and magnetospheric events Year ( ) panels show time variations of parameters: Dst index (solid line), Strong solar flares with importance М5 and higher (upper red lines – upward and downward for west and east flares) and Events in the interplanetary space (dark blue triangles – МС, light green triangles – CIR, brown rhombuses – IS, question marks - uncertain type of event, crosses - are not present the data) (Yermolaev and Yermolaev, 2002).

Solar cycle variations Time variations of annual values of sunspot ( scale on the left), numbers of strong (class of M5 and X) solar flares (scale on the right) and numbers of strong magnetic storms with values of Dst index in a minimum less - 60 nT (scale on the right) (Yermolaev and Yermolaev, 2002)..

Comparison of 669 magnetic storms ( Dst M5 ( ) (From Yermolaev and Yermolaev, 2003). Approximately similar result has been obtained for 126 solar >M0 flares with Solar Energetic Particle events (Yermolaev and Yermolaev, 2002).

Dependence of storm value on flare importance Classification of flares according to left figure. Open and closed – west and east flares. (Yermolaev and Yermolaev, 2003).

Solar coordinates of geoeffective and nongeoeffective flares (From Yermolaev and Yermolaev, 2003).

Geoeffectiveness of 132 halo-CME observed by SOHO ( ) Geoeffectivenesses of Halo-CME and Halo-CME+ Flare events (Yermolaev and Yermolaev, 2002).

Interplanetary events (From Yermolaev, Cos.Res.,1990; Planet. Space Sci., 1991)

Comparison of storms with interplanetary sources 3-year spline smoothed variations in percentages of storms generated by magnetic clouds (MC, blue line) and corotating interaction regions (CIR, green line) [Yermolaev and Yermolaev, Cos. Res., 2002] S and M - strong (Dst < -100 nT, dashed line) and moderate (Dst < - 60 nT, solid line) storms.

Solar events Solar flare - optical class, - X-ray class CME - Halo, - Full halo, - Frontside (Earth-directed) full halo Coronal hole

Dependence of optical importance on X-ray importance for 643 solar flares with X-ray importance > M5 ( )

Earth-directed CME on July 14, 2000 (The Bastile day event). EIT and LASCO C2 images on SOHO (From N. Gopalswamy, COSPAR Colloquium, Taiwan, 2000)

Locations of magnetic stations of Kp and Dst networks

Dependence of Kp index on Dst index for 611 magnetic storms with -300 < Dst < -60 nT during (from Yermolaev and Yermolaev, Cosmic Research, N 6, 2003)

October-November, 2003 storms (Halloween events) (from Veselovsky et al., 2004; Yermolaev et al., 2005)

Comparison of published results on correlation between CME, magnetic cloud (ejecta) and magnetic storm for direct (top panel) and back (bottom panel) tracings. Under each panel there are comparisons between 1- step probability and product of 2-step probabilities (Yermolaev and Yermolaev, Cos.Res. 2003, N6; Yermolaev et al., Planetary and Space Science, N1-3, 2005).

Discussion and Conclusion We studied 669 moderate and strong magnetic storms on the Earth with Dst < -60 nT, 653 solar flares with importance M5 and higher ( ) and 132 halo-CME ( ). Flare and CME geoeffectivnesses were found to be ~35 and ~40 % (Yermolaev and Yermolaev, 2002, 2003a,b). Magnetic clouds and CIRs are the most geoeffective SW sources: they generate ~30% magnetic storms each. The percentages of MC and CIR generated storms have 2 maxima per solar cycle and change in antiphase (Yermolaev and Yermolaev, 2002). obtained estimations of CME influence on the storm both directly (by one step CME => Storm) and by multiplication of probabilities of two steps (CME=> Magnetic cloud; Ejecta and Magnetic cloud; Ejecta => Storm) are close to each other and equal to 40-50% (Webb et al., 1996; Cane et al, 1998; Yermolaev et al., 2000; Gopalswamy et al., 2000; Plunkett et al., 2001; Wang et al., 2002; Berdichevsky et al., 2002; Wu and Lepping, 2002a,b; Yermolaev and Yermolaev, 2002, 2003a,b; Cane and Richardson, 2003; Vilmer et al., 2003);

Conclusions (2) value of % was obtained in papers by Brueckner et al. (1998); St.Cyr et al. (2000); Srivastava (2002); Zhang et al. (2003) by searching for back tracing (Storm => CME) correlation and strongly differs from direct tracing (CME => Storm) results (40-50%); values of % are not confirmed by the two-step analysis of sources of storms since at steps Storm => Magnetic cloud; Ejecta and Magnetic cloud; Ejecta => CME these values are (25-73)% (Gosling et al., 1991; Vennerstroem, 2001; Yermolaev and Yermolaev, 2002; Huttunen et al., 2002) and ~ 40% (Cane et al, 2000) each of which is less than the value obtained by the one-step analysis (Storm => CME); obtained estimations of CME geoeffectiveness (40-50%) are close to estimations of geoeffectiveness of solar flares (30-40%) (Park et al., 2002; Yermolaev and Yermolaev, 2002, 2003a) and exceed them slightly; estimations of CME and solar flare geoeffectiveness can be partially a result of random processes (Yermolaev and Yermolaev, 2002) and, therefore, the forecast of geomagnetic conditions on the basis of observations of the solar phenomena can contain high level of false alarm.

Number of published papers on October-November 2003 events Cosmic Research Geomagnetism and Aeronomy Geophys Res. Lett. J. Geophys. Res. Space Weather

Papers in Cosmic Res. (Sept.2004) and Geomagnetism and Aeronomy (Jan. 2005)

Paper on November 2004 event (Geomagn. and Aeronomy Nov. 2005)