Analysis of Higher-order Ionospheric Effects on Reference Frame Realization and Coordinate Variations

Based on the higher-order ionospheric corrections model，the impact magnitude of higher-or-der ionospheric delay on UPS observables was determined. Then，GPS data from 104 globally distributed IGS stations spanning the years 1999 to 2003 were reprocessed to study the effects of higher-or-der ionospheric corrections on GPS reference frame realization and site coordinates using GAMIT with state of the art models according to the 2010 IERS conventions. We compared the differences generated when applying different geomagnetic models to higher-order delays. Results show that both the reference frame origin and scale are influenced by the higher-order corrections，especially for the Z translation，which can add up to 20 mm，while the X and Y translation had a relatively smaller difference ess than 5 mm. Higher-order ionospheric effects can result in regional bias phenomenon at stations. Differences in the geomagnetic model lead to a change of up to 10 mm for the Z translation. No-table coordinate differences are found in some areas，these results are analyzed and discussed.