What we can learn from the intensity-time profiles of large gradual solar energetic particle events (LGSEPEs) ？ Guiming Le(1, 2,3), Yuhua Tang(3), Liang Zheng(4), Yang Zhang(3) Yuting Zhu(1) 1: National Center for Space Weather, China Meteorological Administration, : Institute of High Energy Physics, Chines Academy of Science, : Department of Astronomy, Nanjing University, Nanjing, China, : Graduate School of Chinese Academy of Science, Beijing, , China ICRC 2011 Beijing 13/08/2011

1 introduction Solar energy particles (SEPs) may be accelerated by both CME-driven shock and solar flare. When the CME enters the interplanetary space, the ICME- driven shock was the only one acceleration source of SEPs. When a ICME moved close to L1 point, the accelerated particles by the ICME driven shock can be observed by satellite located at L1 point. This property can be used to predict the occurrence of a geomagnetic storm.

Energetic ion data show enhancements in flux that herald the approach of interplanetary shocks, usually for many hours before the shock arrival. We present a technique for predicting large geomagnetic storms (Kp  7) following the arrival of interplanetary shocks at 1 AU, using low energy energetic ions (47–65 keV) and solar wind data measured at the L1 point. Smith, Z., Murtagh, W., Smithtro, C. Relationship Relationship between solar wind low-energy energetic ion enhancements and large geomagnetic storms. J. Geophys. Res. 109, A01110, doi: / 2003JA010044]

However, as there are many more large EIEs than large geomagnetic storms, other characteristics were investigated to help determine which EIEs are likely to be followed by large storms. An additional parameter, the magnitude of the post-shock total magnetic field at the L1 Lagrangian point, is introduced here. This improves the identification of the EIEs that are likely to be followed by large storms. (Z.K. Smith *, W.J. Murtagh,2009)

E. Valtonen, T. Laitinen, K. Huttunen-Heikinmaa. Advances in Space Research 36 (2005) 2295–2302

The energetic particles enhancement observed at L1 point indicate an IP shock will reach L1 point. What kind of solar wind structure will pass the earth? Or ICME will pass the earth with what manner? 1 directed away from the Earth? 2 only the limb of ICME will pass the earth, 3 the ICME core will pass the earth? Is still not answered

The ICME moving direction changes always. The predication of the geoeffectiveness of a CME is the problem of how to judge the moving direction of the ICME and the ICME will pass the earth with what manner. The intensity time profile of LGSEPEs reveals the variation of the relative position between the ICME and the observer. Here, we investigate the three types of large gradual solar energetic particle events (observed by GOES satellites)and the associated CMEs will pass the earth with what manner.

The first type: A LGSEPE has only one peak, which occurs no longer after the relative solar flare and the eruption of the associated CME

From top to bottom are the solar x-ray flare, solar wind speed, proton density, magnetic field, z-component of IMF, Tp/Tex ratio, proton , He/p ratio, log Fp (E>10MeV), SYM-H index. The SPE began on 6 May 1998 and the associated geomagnetic activity No shock and sheath observed: The CME directed away the earth

The LGSEPEs occurred on 28/01/2001, and the geomagnetic activity caused by the associated the CME. Only the Shock passed the earth

The second type: A LGSEPE has two peaks with the SEP flux decreasing after the first peak and the second peak lower than the first peak

Both the Shock and ICME passed the earth. However, only the ICME limb passed the earth. The main phase of the geomagnetic storm were only caused by the sheath The LGSEPE began on May 2, 1998

Both the Shock and ICME limb pass the earth. The main phase of the geomagnetic storm was mainly caused by the magnetic cloud(MC) The LGSEPE began on December 13, 2006

The third type: The intensity-time profile of a LGSEPE increased with sustained manner and the solar proton flux peak time basically coincided with the IP sock time, or a LGSEPE has two peaks with the second peak higher than the first one

Both the Shock and ICME passed the earth. the ICME core passed the earth. The main phase of the geomagnetic storm was mainly caused by the magnetic cloud The LGSEPE began on July 14, 2000

Both the Shock and ICME passed the earth. the ICME core passed the earth. The main phase of the geomagnetic storm was mainly caused by the magnetic cloud The LGSEPE began on October 28, 2003

Statistical result: Type 1 Total: no storm, 9 minor storm 8 moderate storm Type 2 total: 12 (-53nT, -205nT, -96nT, -114nT,-288nT,-187nT,-127nT,-383nT,- 84nT,-121nT,-216nT,-147nT) The IP sources for the main phase of the geomagnetic storms are Sheath (9), MC(1), Sheath+ICME(2) Type 3 total: 17 (-155nT,-207nT,-90nT,-301nT, -387nT,-271nT,-102nT,-292nT,- 221nT,-181nT,-109nT,-144nT,-353nT,-197nT,-263nT, -147nT, one followed no storm) Most of the geomagnetic storms were caused by ICME or MC.

Summary 1Type 1: most of them are followed no storm, only small part followed minor or moderate storm. 2Type 2: most of them are followed intense storms, only small part followed moderate storms. Most of the case: shock+sheath+ICMElimb pass the earth 3 Type 3: almost all of them are followed intense storms. Most of this case: shock+sheath+ICMEcore pass the earth

Discussion: 1Total 90 intense geomagnetic storms occurred during solar cycle 23 2LGSEPEs can only predict about 1/3 of them. 3LGSEPEs provide important information of ICMEs propagation in interplanetary space.

Thanks for your attention!