We report preliminary results of a study of two large magnetic clouds, one observed by the WIND spacecraft in October 1995, and the second, even larger, observed by Ulysses in June 1993 when the spacecraft was near 4.6 AU and was heading out of the ecliptic plane. These two clouds, while exhibiting many characteristics in common, are also quite distinguishable. For example, in both clouds, the magnetic field at the scale of the cloud is helically twisted. Similarly, the fluctuating magnetic helicity, Hm, in the interior of both clouds at relatively smaller spatial scales, is quite small and random in sign, in contrast to the nearby solar wind in which large, albeit random, values of Hm occur (Hm = A . B where A and B are the magnetic vector potential and fluctuating magnetic fields, respectively). However, the fluctuating magnetic power in the cloud observed at 1 AU is higher than the power in the ambient solar wind both before and after the cloud. In contrast, the cloud observed by Ulysses exhibits very low fluctuating magnetic power in the cloud. The power spectrum in both the sheath regions surrounding the cloud and in the ambient solar wind is significantly higher. Preliminary analysis of the June 1993 cloud also contains evidence in the dynamic spectrum of the magnetic helicity for a sheath region that shows strongly helical structure in frequency bands. These two clouds are located in quite different regions of the heliosphere and in different solar wind flow regimes (the cloud observed by WIND is being overtaken by a forward shock from a corotating stream). One question that will be addressed is whether or not the observed differences are evolutionary or reflect unique initial states in the solar corona or interaction of the cloud with corotating streams.
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