The tilt angle control of the outer cusp position

For two years, the MAGION-4 satellite collected a unique data set of cusp-l ike plasma observations at middle to high altitudes as a part of the INTERB ALL project. To compare with low-altitude cusp studies, we map our observat ions of cusp-like plasma along magnetic field lines to the 835 km altitude of the DMSP orbit. We use the Tsyganenko 1996 model of the magnetospheric m agnetic field for the mapping, taking into account actual solar wind and IM F parameters from the WIND observations. The footprint positions show a sub stantial latitudinal;dependence on the dipole tilt angle. The dependence ca n be fitted by a line with a slope of 0.15 degrees MLAT per 1 degrees of ti lt. This slope increases for observations made in the vicinity of the magne topause (0.16 degrees MLAT per 1 degrees of tilt) and during periods of sou thward interplanetary magnetic field (0.17 degrees MLAT per 1 degrees of ti lt). Very similar results were obtained for mapping using the Tsyganenko 19 89 model.