Authors: Ying Wang

Eruptive events are the major sources of solar wind and bring magnetic fields and energetic
particles from the solar surface to the near Earth environment and cause geomagnetic storms.
Previous studies suggested that the south-ward magnetic fields play an important role in generating
magnetic cancellation and hence the violent variation of Earth’s magnetosphere. In this study on
the correlation between the orientation of the interplanetary magnetic field (IMF, the counterpart
of CME and ICME at 1AU) and the orientation of eruptive filaments and flux ropes (FRs) near
the solar surface.The results help to determine the magnetic orientation of IMF, and eventually
forecast the geomagnetic storms. This poster focuses on three events, one shows obvious rotation,
one does not show much rotation and the other one is in between. For each event, we determine
the orientation of magnetic flux ropes by the observation of AIA 171Å and HMI magnetograms.
The orientation of the CME upto 32 solar radii (LASCO C2) is estimated by applying the Graduated
Cylindrical Shell (GCS) simulation. The rotation of CME, if exists, can be obtained by comparing
the MFR axis from the GCS modeling results with the MFR orientation of flux ropes/filament.
In addition, the Grad–Shafranov (GS) model is used to reconstruct the flux-rope structure from
in-situ measurements at 1AU to get the flux axis direction. Our case studies demonstrate that the
orientation of the ICME’s Bz component is significantly influenced by both the rotation of the flux
rope axis and the orientation of the filament or flux rope on the solar surface.