Sun-Earth connection Event of Super Geomagnetic Storm on March 31, 2001: the Importance of Solar Wind Density

Li-Bin Cheng, Gui-Ming Le, Ming-Xian Zhao

An X1.7 flare at 10:15 UT and a halo CME with a projected speed of 942 km/s erupted from NOAA solar active region 9393 located at N20W19, were observed on 2001 March 29. When the C…