Abstract
Abstract. Tropospheric delay is one of the major error sources for space geodetic techniques, such as the Global Navigation Satellite Systems (GNSS). Mapping functions are used to scale the delay from zenith direction to the elevation angle of the signal. Several mapping functions have already been published, including the Global Mapping Functions (GMF) and Vienna Mapping Functions 1 (VMF1). Recently, a refined version of VMF1, VMF3, was released. The tropospheric gradients GRAD were also determined using the same data set as VMF3. This study aims to test the performance of VMF3 on GNSS observations in Indonesia, using observations from 21 stations of the permanent GNSS network in Indonesia, InaCORS. Data processing was carried out using Precise Point Positioning in Bernese GNSS Software, version 5.2 for the year 2014. Station coordinates were estimated daily, while the zenith wet delays were estimated every 30 min and tropospheric gradients were estimated hourly. A similar processing scheme was carried out using GMF and VMF1. Generally, the results from VMF3 agree very well with the results from GMF and VMF1, although small biases can be found, especially for the height component. Based on the repeatability, while there is no significant difference for the latitude and longitude, there are slight improvements for the height, particularly compared to GMF. The estimated gradients tend to fluctuate more compared to gradients from GRAD. The correlation coefficients between the estimated gradients and those from GRAD are small, with the largest being 0.65 at site CUKE.
Highlights
Tropospheric delay is one of the major error sources in space geodetic observations
This study aims to assess the performance of VMF3 on Global Navigation Satellite Systems (GNSS) observations in Indonesia
While there are no significant improvements in latitude and longitude, applying VMF3 together with its hydrostatic zenith delays can improve the height component compared to Global Mapping Functions (GMF)/GPT, as seen from the repeatability
Summary
Tropospheric delay is one of the major error sources in space geodetic observations. It needs to be taken into account during the analysis to improve the quality of observation model. Mapping functions are used to scale the tropospheric delays from the zenith direction down to the elevation angle. The tropospheric gradients GRAD (Landskron and Böhm, 2018) were determined through ray-tracing using the same NWMs as VMF3, based on the model by Chen and Herring (1997): L(α, ε) = L0(ε)+mfg(ε)·[Gn ·cos(α)+Ge ·sin(α)] (3). L0 is the product of the zenith hydrostatic and wet delays with their respective mapping functions (the isotropic part): L0(ε) = Lzh · mfh(ε) + Lzw · mfw(ε). This study aims to assess the performance of VMF3 on GNSS observations in Indonesia For this purpose, 21 stations from the Indonesian permanent GNSS network, InaCORS, were chosen based on their location and data availability. 3. The slant tropospheric delays at 5◦ elevation angle from all three mapping functions are shown in Sect.
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