Heliospheric Observations during October – November 2003 Hari Om Vats Physical Research Laboratory Ahmedabad INDIA ICRC meeting, 3 – 10 August 2005, Pune, INDIA Session: SH.3.5

October – November 2003 Ap and Dst indicies show evidence of strong geomagnetic activity Bz is largely positive It remains so during strong geomagnetic activity

October – November 2003

Bastille day event 14 July 2000 Dst is +ve or low –ve for most of the - Bz Dst is highly –ve for + Bz Ap is high and low for - Bz

Bastille day event 14 July 2000

May 4 – (solar wind disappearance event; May 11 – 12)

Conclusions Sunspot number, area, radio flux and flare index show a distinct enhancement during Oct. – Nov Sunspot number, area, radio flux and flare index show a distinct enhancement during Oct. – Nov No apparent correlation with –ve Bz seenNo apparent correlation with –ve Bz seen Log of solar wind pressure gives largely linear relation with Kp Index.Log of solar wind pressure gives largely linear relation with Kp Index. The slopes of log (nPa) and Kp plotsThe slopes of log (nPa) and Kp plots 6 Oct.- Nov most active period 6 Oct.- Nov most active period 4 14 July 2000) Bastille day 4 14 July 2000) Bastille day 2 May 11 – SW disappearance 2 May 11 – SW disappearance

Thank you very much

October-November, 2003 Bastille day event July 14, 2000 Dst seems to have no dependence of solar wind pressure

Flare Coronal Hole High speed streams Characteristcs Duration Vmax Flare Coronal Hole Similar Vats 1992a Catalogue Mavromichalaki et. al 1988

Flare Generated Streams with – and + IMF both seem to generate big geomagnetic storms. Coronal hole associated Stream with – IMF seems to generate a mild geomagnetic storm to generate a mild geomagnetic storm.

Coronal hole associated Streams with – and + IMF generate a mild to Strong geomagnetic storms. Flare Generated Stream with – IMF generate a strong geomagnetic Storm.

Streams with – and + IMF generate geomagnetic storm. Vp and Ap enhamcement plot has two slopes with a threshold at ~850 km/sec. Geomagnetic activity enhancement rate (GAER) is defined as an average increase in Ap value per unit average increase in the peak solar wind velocity (Vp) during the stream. GAER for Vp >850 km/s 0.73 and 0.53 for + and – IMF respectively GAER for Vp <850 km/s 0.08 and 0.09 for + and – IMF respectively

Coronal Hole Flare Coronal Hole Flare Geomagnetic effects Storm duration and Magnitude Associated with flare and Coronal Hole are quite different. Flares produce 2.7 times stronger storms. Coronal holes produce longer (1.5 times) duration storms Vats (1992b) G = 0.64 S – 0.15 G = 0.42 S – 0.35 GAER = 0.58 GAER = 0.12 GAER = 0.07

Conclusions HSS (Flares and coronal holes) enhance geomagnetic activity irrespective of IMF polarity.HSS (Flares and coronal holes) enhance geomagnetic activity irrespective of IMF polarity. HSS >850 km/s GAER 0.73 and 0.53 for + and – IMF resply.HSS >850 km/s GAER 0.73 and 0.53 for + and – IMF resply. HSS <850 km/s GAER 0.08 and 0.09 for + and – IMF resply.HSS <850 km/s GAER 0.08 and 0.09 for + and – IMF resply. HSS (Flares) produce 2.7 times stronger storms.HSS (Flares) produce 2.7 times stronger storms. Coronal holes produce longer (1.5 times) duration storms.Coronal holes produce longer (1.5 times) duration storms. Sunspot number, area, radio flux and flare index show a distinct enhancement during Oct. – Nov Sunspot number, area, radio flux and flare index show a distinct enhancement during Oct. – Nov No correlation with –ve Bz seenNo correlation with –ve Bz seen Log of solar wind pressure gives largely linear relation with Kp Index.Log of solar wind pressure gives largely linear relation with Kp Index. The slope is more (1.5 times) steep during Oct.- Nov than that during Bastille day (14 July 2000)The slope is more (1.5 times) steep during Oct.- Nov than that during Bastille day (14 July 2000)