Properties of ICMEs in the declining phase of solar cycle 23

We compare the physical properties of four Interplanetary Coronal Mass Ejections (ICMEs) that occurred during the declining phase of solar cycle 23 to the average properties of ICMEs observed throughout the solar cycle. The four ICMEs are the ones chosen for the recent Sun-Earth Connection Workshop in Dorking England, and the shocks ahead of these ICMEs passed the Earth on October 29, 2003, November 7, 2004, November 9, 2004, and January 21, 2005. We use ACE solar wind measurements of ICMEs and the Cane and Richardson ICME list, updated to near present conditions, to determine the statistical properties of ICMEs. Key physical properties we examine are the solar wind speed, magnetic field strength, dynamic pressure, proton temperature, and IMF Bz. All four of the selected ICMEs have smooth magnetic fields and three have clear rotations indicative of magnetic clouds. All four ICMEs are fast and have Dst <-100. All have anomalously low plasma proton temperatures except for the October 2003 ICME. The highest speeds and temperatures during the ACE mission to date are associated with the sheath of the October 29, 2003 ICME. The most anomalously low temperatures in the ACE mission occur in the ICME that immediately followed on October 31, 2003.