Comment on "A statistical comparison of solar wind sources of moderate   and intense geomagnetic storms at solar minimum and maximum" by Zhang, J.-C.,   M. W. Liemohn, J. U. Kozyra, M. F. Thomsen, H. A. Elliott, and J. M. Weygand,   JGR, 2006
  Conditions in the solar wind resulting in magnetic storms on the Earth are a subject of long and intensive investigations. Recently Zhang et al. (2006), published a paper, where they used superposed epoch analyses method to study solar wind features during 549 geomagnetic storms. Unfortunately, the used methodical approach has not allowed to improve essentially understanding of relation of magnetic storms with conditions in the solar wind, and first of all for the following reasons: (1) they did not take into account of existance of storms generated by different types of solar wind, and (2) they took minimum Dst index time as epoch zero time rather than storm onset. 
Yu. I. Yermolaev, M. Yu. Yermolaev and I. G. Lodkina