Observations from the ACE and STEREO spacecrafts showing interplanetary structures associated with the event on 2006 December 13. The passage of different structures is indicated by the different colored intervals, i.e., the shock sheath (blue interval “1”), the interplanetary magnetic arcades (pink interval “2”), and the interplanetary CS (yellow interval “3”), as well as the MC (gray interval “4”). Panel a) shows the distribution of electron pitch angles detected by ACE. Panels b) and c) show the magnetic field magnitude and the field components B_x (black line), B_y (green line), and B_z (red line), in GSM coordinates. The current density calculated from the STEREO A and B magnetic field data is presented in Panel d), in which the current concentrations as denoted by the arrow are believed to originate in the transverse CS during the CME initiation. Panels e) to g) show the corresponding plasma temperature, density, and velocity from ACE observations.