The magnetic field characteristics of a sample set of helical magnetic flux rope ICMEs (magnetic clouds) observed by the Wind and ACE satellites in solar cycle 23 and their related space weather effects are investigated. The solar source regions of the magnetic clouds were identified using remote sensing observations of the SOHO, Yohkoh and TRACE spacecraft together with ground-based H_α images. Each cloud observed at 1 AU could be uniquely associated with a well defined frontside halo CME some days before the cloud's arrival at 1 AU. The hemispheric origin is consistent with the expected hemispheric helicity pattern. The space weather effects of the clouds were quite variable, depending on their internal magnetic field configuration and speed of propagation.
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