Ionospheric effects on differential GPS applications during auroral substorm activity

The use of the Global Positioning System (GPS) technology has become increa singly incorporated into airborne remote sensing applications over the past decade. While GPS positioning results may prove adequate for several appli cations at present, users should expect to experience degraded positioning accuracies over the next few years due to auroral substorm activity. Such d egraded accuracies will arise from increased spatial decorrelation of ionos phere range delay errors in differential GPS applications, as the ionospher ic activity increases during solar maximum. In this paper, the spatial deco rrelation of ionospheric range delay is estimated during a substorm event a nd compared with "quiet" time values. Positional errors tin both vertical a nd horizontal measurements) in the range 60-80 cm RMSE were observed during a 1997 substorm event that is representative of the activity anticipated a t solar maximum around the year 2000. (C) 1999 Elsevier Science B.V. All ri ghts reserved.