Magnetospheric Magnetic Field in the Outer Cusp Region: Comparison of Measurements Obtained from the INTERBALL-1 Satellite and from the T96 Model

The Earthʹs magnetospheric field in the outer cusp region in the northern hemisphere, determined from the Tsyganenkoʹs model, is compared with the data obtained from the INTERBALL-1 satellite for a 3-year period. To obtain statistically reliable information, all data were reduced to a coordinate system specially developed for the outer cusp region. The Tsyganenko-96 model is shown to have a considerable systematic distinction between the measured and model magnetic field strengths. This distinction is shown to be localized in the outer cusp region, where the observed plasma concentration approaches the density in the magnetosheath. The observed distinction between model and measured magnetic fields can be attributed to diamagnetic currents flowing over the outer cusp boundary.