The impact of severe ionospheric conditions on the GPS hardware in the Southern Polar Region

The primary objective of this paper is to present results of an experiment to determine the effects of moderate and severe ionospheric conditions on the GPS signal tracking by different L1/L2 receivers operating in the Southern Polar region. In this study, data collected by the Ohio State University (OSU) and the U.S. Geological Survey (USGS) joint team within the TAMDEF (Transantarctic Mountains Deformation) network were used together with the IGS and UNAVCO Antarctic stations. Seventeen Antarctic stations equipped with different dual-frequency GPS hardware were selected, and data were evaluated for two 24-hour periods of severe ionospheric storm (October 29th, 2003) and active ionospheric conditions (moderate storm of November 11th, 2003). The UNAVCO QC software was used to carry out the analyses. Depending on the data sampling rate and the elevation mask angle, the expected number of observations per receiver/satellite was compared to the actual number of measurements collected during the ionospheric storms, with a special emphasis on L2 data. Depending on the receiver model, the number of lost measurements during the severe ionospheric conditions ranged from 0.5% to 30.0%. In addition, the number of cycle slips (CS) per number of observations as a function of receiver model was computed; it shows great variation for different hardware. The possible variability of the ionospheric conditions at some of these sites (due to their separation) is considered in the conclusions. The results indicate that depending on the severity of ionospheric conditions, there is a significant difference in the impact on the operations of different hardware models. Thus, careful hardware selection is needed to assure data quality/continuity when observations may be affected by severe ionospheric disturbances.