The first “Halloween storm”, days 302–303 (29–30 October), 2003. From the top panel downward are the solar wind velocity (Vsw), density (Nsw), ram pressure (Psw), temperature (Tsw), plasma β, magnetic field magnitude (Bo), the Bx and By components (in the same panel) and Bz in GSM coordinates. The bottom four panels are the SMU and AU indices (in the same panel), the SML and AL indices (in the same panel), the SYM-H and Dst indices (in the same panel) and the GIC intensities. In the solar wind/interplanetary and geomagnetic indices panels, blue and black curves show 1 min and 1 h resolution data, respectively. The x-axis shows UT in the unit of day of year (DOY). The horizontal red line in the GIC panel indicates the GIC = 30 A intensity level. A vertical black dashed line indicates the time of an interplanetary shock.