Abstract
We present the first set of examples of the shrinkage of large-scale nonflare loops in the solar corona, observed by the Yohkoh Soft X-Ray Telescope in 1993 February. A large and isolated active region exhibited an unusual south-north asymmetry in coronal dynamics and heating. The northern part, referred to the main magnetic axis, showed episodic expansion and heating. In contrast, the southern part displayed obvious shrinking and cooling. This asymmetry was correlated with a severe asymmetry in the surface magnetic activity revealed by Huairou vector magnetograms. Observations suggest that this shrinkage is not an apparent motion, but a real contraction of coronal loops that brighten as a result of heating at footpoints followed by gradual cooling.
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