In open models of the magnetosphere, the cleft is the dayside boundary between open and closed geomagnetic field lines. There is considerable evidence that, within the cleft region, the effects of the full range of solar wind-magnetosphere-ionosphere coupling phenomena can be observed. These include Brikeland currents, strong electric fields, particle energization within localized regions, and intense ionospheric heating. This grant is directed towards experimental and theoretical studies of the cleft and its dynamic behavior in response to variations in the solar wind and IMF. Coordinated analysis, using various combinations of data, will be performed. These data include radar observations, magnetometer array data, satellite data, as well as other ground data. *** //
