SIMULTANEOUS HF-RADAR AND DMSP OBSERVATIONS OF THE CUSP

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. Copyright 1990 by the American Geophysical Union.