Fig. 13

Sketch of the geometric relationship (in the magnetic meridian) that determines where a plume (green-lined bar with yellow fill) would be detectable with the EAR. The ‘blind spot’ is a region, below the base of the local N profile, where N is too low to support radar backscatter, regardless of whether an EPB is present on those B lines over the dip equator (which is also shown with a green-lined bar with yellow fill). In other words, plumes can be detected only at altitudes above the blue B curve