Ionospheric effects on differential GPS applications during auroral substorm activity

Ž . The use of the Global Positioning System GPS technology has become increasingly incorporated into airborne remote sensing applications over the past decade. While GPS positioning results may prove adequate for several applications at present, users should expect to experience degraded positioning accuracies over the next few years due to auroral substorm activity. Such degraded accuracies will arise from increased spatial decorrelation of ionosphere range delay errors in differential GPS applications, as the ionospheric activity increases during solar maximum. In this paper, the spatial decorrelation of ionospheric range delay is estimated during a substorm event and compared with ‘‘quiet’’ time values. Ž . Positional errors in both vertical and horizontal measurements in the range 60–80 cm RMSE were observed during a 1997 substorm event that is representative of the activity anticipated at solar maximum around the year 2000. q 1999 Elsevier Science B.V. All rights reserved.