The impact of temporal ionospheric gradients in Northern Europe on relative GPS positioning

The effect of temporal ionospheric gradients on measured baselines was studied at mid and high latitudes. The experimental analysis was carried out from 14 to 17 July 2000 (day of year (DOY) from 196 to 199), which includes both quiet and stormy days for comparison purposes. Temporal ionospheric gradients caused by the geomagnetic storm affect the ambiguity resolution, resulting in unresolved ambiguities up to 61% for the time periods 21:00-24:00 UT on DOY 197 and 00:00-03:00 UT on DOY 198 for the Kiru-Soda and Kiru-Tro1 baselines (high-latitude, Kp>7). RMS of epoch by epoch coordinate residual change gradually increases from 1.45, 0.96 and 3.67 cm at 9:00-12:00 UT on DOY 197 to 1.79, 1.22 and 4.61 cm at 0:00-03:00 UT on DOY 198 (Kp>8) for the same baselines' north, east and up coordinate components, respectively. There are no remarkable effects for the selected baselines in the mid-latitude region in both ambiguities and coordinate components.