An evolution of antiparallel merging

It has been suggested (Crooker, 1979) that the geomagnetic field and the merge at the dayside magnetopause along lines formed by the loci of points where the fields are antiparallel. These antiparallel merging lines curve outward from the cusps, one in each hemisphere. Here a three-dimensional magnetopause model in which the antiparallel merging lines become chains of neutral points is described. The model is constructed by overlapping shielding currents of the geomagnetic field and the IMF in a layer of finite thickness. The global topology of the model explains the observed disappearance of flux-transfer events when the IMF turns northward and the dearth of flux-transfer events in the subsolar region.