In this study we compare meteorological observations from a set of different measuring devices with each other in order to derive information about their quality and mutual consistency. We consider data from terrestrial measuring devices, satellite observations, space observations, weather balloons and weather models provided by weather agencies. The results in general show very good accordance and interchangeability between the various solutions.
The precise knowledge of the orientation of an Earth fixed coordinate system with respect to space is of great importance for all tasks of positioning and navigation. In this work we investigated the potential of combining measurements of Very Long Baseline Interferometry and a large ring laser gyroscope to derive highly resolved parameters describing this orientation. The ring laser is not yet at the same level of accuracy and therefore does not substantially influence the results.
Satellite Laser Ranging is one of the four fundamental geodetic space techniques for the accurate determination of geodetic key parameters related to the Earth’s geometry, rotation and gravity field. As the current global SLR station distribution is quite inhomogeneous, a simulation study has been performed in order to determine locations on Earth where additional SLR sites will be most valuable for an improvement of the results, the Antarctic region having been identified as a first priority.
In this article we analyze the benefit of computing a combined solution from individual orbit solutions for the low Earth orbiting satellite Sentinel-3A. The selected combination scheme for calculating the combined solution is Variance Component Estimation. It could be shown that a combination of individual solutions can be beneficial in terms of Satellite Laser Ranging validation. In our opinion the findings are well transferable to other satellite missions.
Here, three schemes have been considered for remedying the rank deficiency of the GNSS tomography problem. For this purpose, the Virtual Reference Stations (VRS) and horizontal and vertical constraints have been defined to analyze the impact of different constraints on the accuracy of the reconstructed refractivity field. The obtained results illustrate that applying VRS stations in the sparse GNSS Network can lead to a better solution compared to applying horizontal and vertical constraints.
The combination of VLBI Intensive and GNSS Rapid products on the base of Normal Equations for a consistent estimation of a full set of EOPs is focused. In this context, meaningful investigations of the obtained accuracies have been carried out. The combined estimates of polar motion, UT1 and their associated rates are therefore discussed and compared with respect to the official reference series and the specific single solutions, respectively.
Nowadays, new GNSS, like European Galileo or Chinese Beidou are available. Some members of the International GNSS Service (IGS) provide multi-GNSS precise satellite orbits, but no final orbit combination exists yet. We developed a new algorithm to combine satellite orbits for all GNSS constellations. Two different strategies were applied. To validate our results we compared our GPS orbits with the official IGS orbits. Our results show that the best strategy applied reached an agreement ~15 mm.
Tropospheric delays must be taken into account when analyzing GNSS data. Several tropospheric delay models and mapping functions are available, for instance the Vienna Mapping Functions 1 (VMF1) and the Global Mapping Function (GMF). Recently, a refined version of VMF1, VMF3, has been released. This study aims to assess the performance of VMF3 for GNSS observations in Indonesia, by analyzing the data using Bernese GNSS Software, version 5.2 with Precise Point Positioning method.
The SAR Copernicus Sentinel-1 satellites require a high orbit accuracy of 5 cm in comparison to external processing facilities. Orbit analyses showed discrepancies between the results of the two Sentinel-1 satellites being identical in construction. Follow-up estimation of GPS antenna offsets shows the sensitivity to different orbit and observation models. Consistent results may be achieved for both satellites when applying estimated antenna offsets considering self-shadowing assumptions.
We compute gravity field solutions from kinematic orbit positions of GRACE. These positions are derived from GPS based observations, and hence, they are contaminated by measurement noise. We present three methods of dealing with the noise in the data to obtain not only high-quality gravity field solutions but also an accurate quality information of the gravity fields.