Preprints

Filtering by Subject: Other Physical Sciences and Mathematics

GPS sidereal filtering: coordinate- and carrier-phase-level strategies

Ahmed Ragheb, Peter John Clarke, Stuart Edwards

Published: 2017-11-13
Subjects: Civil and Environmental Engineering, Civil Engineering, Earth Sciences, Engineering, Other Civil and Environmental Engineering, Other Earth Sciences, Other Physical Sciences and Mathematics, Physical Sciences and Mathematics

Multipath error is considered one of the major errors affecting GPS observations. One can benefit from the repetition of satellite geometry approximately every sidereal day, and apply filtering to help minimize this error. For GPS data at 1 second interval processed using a double-difference strategy, using the day-to-day coordinate or phase residual autocorrelation determined with a 10 hour [...]

Basis functions for the consistent and accurate representation of surface mass loading

Peter John Clarke, David Lavallee, Geoffrey Blewitt, et al.

Published: 2017-11-13
Subjects: Applied Mathematics, Earth Sciences, Environmental Indicators and Impact Assessment, Environmental Monitoring, Environmental Sciences, Geophysics and Seismology, Numerical Analysis and Computation, Oceanography and Atmospheric Sciences and Meteorology, Other Earth Sciences, Other Environmental Sciences, Other Oceanography and Atmospheric Sciences and Meteorology, Other Physical Sciences and Mathematics, Physical Sciences and Mathematics

Inversion of geodetic site displacement data to infer surface mass loads has previously been demonstrated using a spherical harmonic representation of the load. This method suffers from the continent-rich, ocean-poor distribution of the geodetic data, coupled with the predominance of the continental load (water storage and atmospheric pressure) compared with the ocean bottom pressure (including [...]

Using filtered and semi-continuous high rate GPS for monitoring deformations

Ahmed Ragheb, Stuart Edwards, Peter John Clarke

Published: 2017-11-13
Subjects: Civil and Environmental Engineering, Civil Engineering, Construction Engineering and Management, Earth Sciences, Engineering, Environmental Monitoring, Environmental Sciences, Geophysics and Seismology, Geotechnical Engineering, Other Civil and Environmental Engineering, Other Earth Sciences, Other Environmental Sciences, Other Physical Sciences and Mathematics, Physical Sciences and Mathematics, Structural Engineering

Multipath is a major sidereally-repeating error affecting precise GPS positioning and deformation monitoring. Because satellite-receiver geometry repeats almost exactly every sidereal day, filtering can reduce multipath in near-static situations. Here, we investigate how sidereal filtering can be used in a switched multi-antenna array system providing semi-continuous GPS data, which may be [...]

J2: an evaluation of new estimates from GPS, GRACE and load models compared to SLR

David Lavallee, Philip Moore, Peter John Clarke, et al.

Published: 2017-11-13
Subjects: Earth Sciences, Environmental Monitoring, Environmental Sciences, Geophysics and Seismology, Other Earth Sciences, Other Environmental Sciences, Other Physical Sciences and Mathematics, Physical Sciences and Mathematics

Changes in J2, resulting from past and present changes in Earth’s climate, are traditionally observed by Satellite Laser ranging (SLR). Assuming an elastic Earth, it is possible to infer changes in J2 from changes in Earth’s shape observed by GPS. We compare estimates of non-secular J2 changes from GPS, SLR, GRACE and a load model. The GPS and SLR annual signals agree but are different (16%) to [...]

An examination of network RTK GPS services in Great Britain

Stuart Edwards, Peter John Clarke, Nigel Penna, et al.

Published: 2017-11-13
Subjects: Civil and Environmental Engineering, Civil Engineering, Construction Engineering and Management, Earth Sciences, Engineering, Environmental Monitoring, Environmental Sciences, Geophysics and Seismology, Other Civil and Environmental Engineering, Other Earth Sciences, Other Environmental Sciences, Other Physical Sciences and Mathematics, Physical Sciences and Mathematics

As of March 2009, network real-time kinematic (RTK) GPS surveying is available in Great Britain with the aid of two commercial service providers, Leica’s “SmartNet” and Trimble’s “VRS Now”, both of which rely largely on the Ordnance Survey’s “OS Net” network of around 120 continuously operating reference stations. With the aim of testing the performance of Network RTK under both ideal and [...]

Ocean tide loading and relative GNSS in the British Isles

Peter John Clarke, Nigel Penna

Published: 2017-11-13
Subjects: Civil and Environmental Engineering, Earth Sciences, Engineering, Environmental Monitoring, Environmental Sciences, Geophysics and Seismology, Oceanography and Atmospheric Sciences and Meteorology, Other Civil and Environmental Engineering, Other Earth Sciences, Other Environmental Sciences, Other Oceanography and Atmospheric Sciences and Meteorology, Other Physical Sciences and Mathematics, Physical Sciences and Mathematics

Ocean tide loading (OTL) affects all parts of the British Isles to varying degree, causing peak-to-peak vertical displacements of up to 13 cm in South-West England over semi-diurnal and diurnal timescales. Lateral displacements are typically around one-third of the magnitude of vertical displacements at a point, so are also considerable for carrier phase GNSS surveying. Using a recent numerical [...]

Enhancement of the accuracy of single epoch GPS positioning for long baselines by local ionospheric modelling

Mohammed Assiadi, Stuart Edwards, Peter John Clarke

Published: 2017-11-13
Subjects: Civil and Environmental Engineering, Civil Engineering, Earth Sciences, Engineering, Other Civil and Environmental Engineering, Other Earth Sciences, Other Physical Sciences and Mathematics, Physical Sciences and Mathematics

Single-epoch relative GPS positioning has many advantages, especially for monitoring dynamic targets .In this technique, errors occurring in previous epochs cannot affect the position accuracy at the current epoch, but careful processing is required, and resolving carrier phase ambiguities is essential. Statistical ambiguity resolution functions have been used to determine the best values of [...]

A general model for the helical structure of geophysical flows in channel bends

Maria Azpiroz-Zabala, Matthieu Cartigny, Esther J. Sumner, et al.

Published: 2017-10-31
Subjects: Civil and Environmental Engineering, Earth Sciences, Engineering, Environmental Engineering, Environmental Sciences, Fluid Dynamics, Geology, Geomorphology, Geophysics and Seismology, Hydrology, Life Sciences, Natural Resources and Conservation, Oceanography, Oceanography and Atmospheric Sciences and Meteorology, Oil, Gas, and Energy, Other Physical Sciences and Mathematics, Physical Sciences and Mathematics, Physics, Risk Analysis, Sedimentology

Meandering channels host geophysical flows that form the most extensive sediment transport systems on Earth (i.e. rivers and submarine channels). Measurements of helical flow structures in bends have been key to understanding sediment transport in rivers. Turbidity currents differ from rivers in both density and velocity profiles. These differences, and the lack of field measurements of turbidity [...]

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