Multi-satellite observations of the polar cap arcs

Using the multi-satellite (EXOS-C, Viking, DMSP) data, we have investigated the conjugacy and the accerelation region in the polar cap region. Observations indicated that the polar cap arcs were conjugate in both hemispheres, which suggests that they occur on closed field lines. Particle measurements on the polar cap arc were simultaneously made on the same field line by EXOS-C (500 km) and Viking (10,000 km). Comparing these data it can be concluded that the acceleration region exists in the altitude range between both satellites. (author)