Summary
This paper is an extension of the paper by King et al. (2000), where two techniques were described to process GPS data collected on a floating Antarctic ice shelf. King et al. (2000) showed good agreement for the vertical component using both processing techniques but the comparison of horizontal components was not included. In this paper, we give a more complete comparison between the two processing approaches and the resulting comparison of horizontal coordinates. Due to particular disadvantages of GPS processing in the Amery Ice Shelf (AIS) region, solutions with floating ambiguity terms are usually used in the analysis instead of fixed ambiguity solutions. However, we demonstrate that when different treatments of ambiguity parameters are used in the processing, significant effects on the horizontal coordinate accuracy are seen. More importantly, ambiguity float solutions yield misleading periodical signals in the horizontal components. This could lead to a misinterpretation of geophysical processes, such as ice shelf dynamics.