Interplanetary 1 AU near-Earth data for cycle 23 minimum (2008) compared to cycle 22 minimum (1996). The interplanetary magnetic field and solar wind speed are shown from 1990 through 2010 in the second and fourth panels from the top. The bottom panel gives the geomagnetic ap index. The top and the third panels are the sunspot number and the cosmic ray flux at Oulu, Finland. The figure is taken from Tsurutani et al. (2011a).