Investigation of GPS positioning accuracy during the seasonal variations

The aim of this study is to investigate the accuracy of GPS (Global Positioning System) positioning that determined by GPS measurements carried out during the seasonal variations. The observations have been analysed to determine how the accuracy of derived relative positions of GPS stations depends on the baseline length, the duration of observing session during the seasonal variations.For this purpose, GPS data sets of 12 MAGNET (Marmara Continuos GPS Network) stations, ISTA and TUBI IGS (International GNSS Service) stations were selected three days of each months in 2009. GPS observations were constrained by fixing the ITRF 2005 reference frame and were selected to form 13 baselines varying from 6 to 238 km. Each days of 24h GPS data were subdivided into mutually non-overlapping 12h, 8h, 6h and 4h sessions and were processed using the Bernese 5.0 GPS software.The RMS values was obtained combining with the results of the repeability values of the days? adjustments, ambiguity statistics, corelation statistics , seasonal effects duration effects on the accuracy of coordinate components were analyzed.