The Geospace Environment Modeling (GEM) Program is directed toward modeling the coupled solar wind/magnetosphere/ionosphere system. The inter-calibration of ground-based observations of the ionosphere and satellite observations has been identified as an essential step in tying together the data to produce a global picture of geospace.

On October 10, 1988 the DMSP-F9 satellite passed through the southern hemisphere cusp while a coherent scatter HF-radar was observing 10-m scale irregularities present in the ionosphere. The combined data indicate that these irregularities were being generated in the cusp, and that the cusp was a region of greater than normal electric field turbulence. The radar data indicate that the cusp was co-located with the region where the ionospheric convection rotated from sunward to anti-sunward with increasing latitude. These observations provide an unambiguous case where simultaneous satellite and ground-based observations of the cusp can be compared. ¿ American Geophysical Union 1990