A comparison of the tsyganenko model predicted and measured geomagnetic cutoff latitudes Original Research Article

We have computed world grids of geomagnetic vertical cutoff rigidities employing the Tsyganenko magnetospheric model for all integer magnetic activity levels specified by the Kp magnetic index. In order to test the accuracy of these results, we present comparisons with the measured cutoff latitudes observed by the SAMPEX spacecraft. In general we find that during magnetically active times the measured cutoffs are about one degree lower (equatorward) in latitude than the cutoffs determined from the trajectory-tracing method using the Tsyganenko magnetospheric model. We also find that the 3-hour averaged Kp index is not responsive to dynamic magnetospheric activity, and a more frequent temporal description of the magnetic activity is desirable.