| 1. |
- Rajner, Marcin, 1982
(author)
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Detection of ice mass variation using GNSS measurements at Svalbard
- 2018
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In: Journal of Geodynamics. - : Elsevier BV. - 0264-3707. ; 121, s. 20-25
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Journal article (peer-reviewed)abstract
- We compare observed uplift rates of Global Navigation Satellite Systems (GNSS) with geophysical predictions at sites located on Spitsbergen. We show here that using modern postglacial rebound models, realistic mass balance for Present Day Ice Melting (PDIM) and taking the deglaciation of the Little Ice Age (LIA) into account, we can close the overall uplift budget at a level of a few millimetres per year. For this study we used GNSS data from well-established geodetic sites in Ny-Ålesund and the new data from Hornsund. The significant increase of uplift rates since the beginning of 2011 was observed at both gnss sites. These height changes are attributed to recent increased ice mass loss of 6.0 Gt yr−1 for Svalbard. The total mass loss is estimated at 14.7 Gt yr−1. Ice unloading caused also a noticeable increase of distance between Ny-Ålesund and Hornsund. We show that the specific location of the two sites facilitates inference of differential mass loss within the Svalbard Archipelago.
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| 2. |
- Scherneck, Hans-Georg, 1951, et al.
(author)
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Using a Superconducting Gravimeter in Support of Absolute Gravity Campaigning — A Feasibility Study
- 2019
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In: Geophysica. - 0367-4231 .- 2324-0741. ; 54:1, s. 117-135
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Journal article (peer-reviewed)abstract
- Preparing for joint analysis of absolute gravity (AG) campaigns, this report investigates whether a stationary superconducting gravimeter (SCG) can provide a long-term stable measurement of sitedependent perturbations that help in reduction to the local value of little-g and its secular rate of change. The crucial element concerns the discrimination of instrumental drift components from trends of physical origin, where biasses in the inferred long-term drift rate may offset the rate that the reduced AG campaigns deliver. Thus, the main objective is to include a set of gravity models and proxy series as complete as possible in the SCG analysis. Findings indicate consistency for dg/dt in the drift model at the 0.5 nm/s2/yr level using observations at Onsala Space Observatory from 2009 to 2017. In pursuit of the overriding objective to improve the accuracy of secular rates of gravity owed to Glacial Isostatic Adjustment, our approach may even put numbers on a range of long-term changes due to atmosphere, hydrology, and non-tidal ocean loading, namely the rate biasses reported here.
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| 3. |
- Tercjak, Monika, et al.
(author)
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On the Influence of Diurnal and Subdiurnal Signals in the Normal Vector on Large Ring Laser Gyroscope Observations
- 2020
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In: Pure and Applied Geophysics. - : Springer Science and Business Media LLC. - 0033-4553 .- 1420-9136. ; 177:9, s. 4217-4228
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Journal article (peer-reviewed)abstract
- The ring laser gyroscope (RLG) technique has been investigated for over 20 years as a potential complement to space geodetic techniques in measuring Earth rotation. However, RLGs are also sensitive to changes in their terrestrial orientation. Therefore in this paper, we review how the high-frequency band (i.e. signals shorter than 0.5 cycle per day) of the known phenomena causing site deformation contribute to the RLG observable, the Sagnac frequency. We study the impact of solid Earth tides, ocean tidal loading and non-tidal loading phenomena (atmospheric pressure loading and continental hydrosphere loading). Also, we evaluate the differences between available models of the phenomena and the importance of the Love numbers used in modeling the impact of solid Earth tides. Finally, we compare modeled variations in the instrument orientation with the ones observed with a tiltmeter. Our results prove that at the present accuracy of the RLG technique, solid Earth tides and ocean tidal loading effects have significant effect on RLG measurements, and continental hydrosphere loading can be actually neglected. Regarding the atmospheric loading model, its application might introduce some undesired signals. We also show that discrepancies arising from the use of different models can be neglected, and there is almost no impact arising from the use of different Love numbers. Finally, we discuss differences between data reduced with tiltmeter observations and these reduced with modeled signal, and potential causes of this discrepancies.
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