Impact of Different Tropospheric Models on GPS Baseline Accuracy: Case Study in Thailand," presented at

Abstract. It is generally known that the atmospheric effects on the GPS signals are the most dominant spatially correlated biases. The atmosphere causing the delay in GPS signals consists of two main layers, ionosphere and troposphere. The ionospheric bias can be mitigated using dual frequency receivers. Unlike the ionospheric bias, the tropospheric bias cannot be removed using the same procedure. Compensation for the tropospheric bias is often carried out using a standard tropospheric model. Most standard tropospheric models were experimentally derived using available radiosonde data, which were mostly observed on the European and North American continents. In order to determine the best-fit standard tropospheric model with the GPS data collected in Thailand, investigations on the impact of different standard tropospheric models on GPS baseline accuracy are therefore needed. This paper aims to compare the GPS positioning results derived from the use of three different standard tropospheric models, namely the Saastamoinen model, Hopfield model and Simplified Hopfield model. In this study, both short and medium length baseline data sets were tested. In addition, each baseline data set is further divided into two scenarios, flat terrain and rough terrain. Overall results indicate that there are no statistically significant differences in the performance of the three tropospheric models. However, the use of the Saastamoinen and the Hopfield models tends to produce more reliable results than the use of the Simplified Hopfield model