Geomagnetic Crochets and Associated Ionospheric Current Systems

It is shown that time‐structure analysis of geomagnetic crochets can be useful in the ground‐based detection of XUV radiation from solar flares. The crochets often manifest a composite structure that consists of a ‘fast’ component presumably produced by EUV radiation (100–1000Å) and a ‘slow’ component produced by soft X rays (1–100Å). This composite structure is taken into account in the proposed method of analysis for crochet current systems. Some preliminary results are given from the simulation studies of S q and crochet current systems. These studies are intended to probe into the nature of the atmospheric winds that drive the ionospheric dynamo and that generate both the S q and crochet currents.