Linking two consecutive non-merging magnetic clouds with their solar sources,

DASSO S.; MANDRINI C.H.; SCHMIEDER, B.; CREMADES, H.; CID, C.; CERRATO, Y.; SAIZ, E.; DEMOULIN P.; ZHUKOV, A. N.; RODRIGUEZ L.; ARAN, A.; MENVIELLE, M.; POEDTS, S.

JOURNAL OF GEOPHYSICAL RESEARCH

Año: 2009 vol. 114 p. 210901 - 210917

0148-0227

On 15 May 2005, a huge interplanetary coronal mass ejection (ICME) was observednear Earth. It triggered one of the most intense geomagnetic storms of solar cycle 23(Dstpeak = -263 nT). This structure has been associated with the two-ribbon flare, filamenteruption, and coronal mass ejection originating in active region 10759 (NOAA number).We analyze here the sequence of events, from solar wind measurements (at 1 AU) andback to the Sun, to understand the origin and evolution of this geoeffective ICME. From adetailed observational study of in situ magnetic field observations and plasma parametersin the interplanetary (IP) medium and the use of appropriate models we propose analternative interpretation of the IP observations, different to those discussed in previousstudies. In our view, the IP structure is formed by two extremely close consecutivemagnetic clouds (MCs) that preserve their identity during their propagation through theinterplanetary medium. Consequently, we identify two solar events in Ha and EUVwhich occurred in the source region of the MCs. The timing between solar and IP events,as well as the orientation of the MC axes and their associated solar arcades are in goodagreement. Additionally, interplanetary radio type II observations allow the tracking ofthe multiple structures through inner heliosphere and pin down the interaction region to belocated midway between the Sun and the Earth. The chain of observations from thephotosphere to interplanetary space is in agreement with this scenario. Our analysis allowsthe detection of the solar sources of the transients and explains the extremely fast changesof the solar wind due to the transport of two attached (though nonmerging) MCswhich affect the magnetosphere.