MAGNETIC CLOUDS AT SECTOR BOUNDARIES

Eight of the 14 magnetic clouds in the period August 1978 to February 1982, previously identified in solar wind data by their smooth magneti c field rotations, were encountered at sector boundaries. Most of thes e differed from those not encountered at sector boundaries in two ways . First, the accompanying counterstreaming electrons, indicating close d magnetic topology, on average spanned intervals more than twice as l ong as the identified clouds. Second, the field rotations within the i dentified clouds appear to form part of larger-scale rotations beyond the cloud boundaries that roughly coincide with the counterstreaming e lectrons. The results suggest that the documented clouds were parts of larger transient structures that are best observed in their entirety at sector boundaries. The data are consistent with spacecraft passages through both the leading and trailing sections of kinematically disto rted flux rope loops rooted to the Sun.