First results of the Nordic and Baltic GNSS Analysis Centre

Abstract The Nordic Geodetic Commission (NKG) has launched a joint NKG GNSS Analysis Centre that aims to routinely produce high qualityGNSS solutions for the common needs of the NKG and the Nordic and Baltic countries. A consistent and densified velocity field is needed for the constraining of the gla-cial isostatic adjustment (GIA) modelling that is a key component of maintaining the national reference frame realisations in the area. We described the methods of the NKG GNSS Analysis Centre including the defined processing setup for the local analysis centres (LAC) and for the combination centres.We analysed the results of the first 2.5 years (2014.5-2016). The results showed that different subnets were consistent with the combined solution within 1-2 mm level. We observed the so called network effect affecting our reference frame alignment. However, the accuracy of the reference frame alignment was on a few millimetre level in the area of the main interest (Nordic and Baltic Countries). TheNKGGNSS AC was declared fully operational in April 2017.

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Observing UT1-UTC with VGOS

Earth Planets and Space ◽

10.1186/s40623-021-01396-2 ◽

2021 ◽

Vol 73 (1) ◽

Author(s):

Rüdiger Haas ◽

Eskil Varenius ◽

Saho Matsumoto ◽

Matthias Schartner

Keyword(s):

Standard Deviation ◽

Reference Frame ◽

Earth Rotation ◽

Space Observatory ◽

International Earth Rotation ◽

Onsala Space Observatory ◽

X Band ◽

First Results

AbstractWe present first results for the determination of UT1-UTC using the VLBI Global Observing System (VGOS). During December 2019 through February 2020, a series of 1 h long observing sessions were performed using the VGOS stations at Ishioka in Japan and the Onsala twin telescopes in Sweden. These VGOS-B sessions were observed simultaneously to standard legacy S/X-band Intensive sessions. The VGOS-B data were correlated, post-correlation processed, and analysed at the Onsala Space Observatory. The derived UT1-UTC results were compared to corresponding results from standard legacy S/X-band Intensive sessions (INT1/INT2), as well as to the final values of the International Earth Rotation and Reference Frame Service (IERS), provided in IERS Bulletin B. The VGOS-B series achieves 3–4 times lower formal uncertainties for the UT1-UTC results than standard legacy S/X-band INT series. The RMS agreement w.r.t. to IERS Bulletin B is slightly better for the VGOS-B results than for the simultaneously observed legacy S/X-band INT1 results, and the VGOS-B results have a small bias only with the smallest remaining standard deviation.

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Progress Report on the Southern Proper Motion Program

Symposium - International Astronomical Union ◽

10.1017/s0074180900228404 ◽

1995 ◽

Vol 166 ◽

pp. 357-357

Author(s):

I. Platais ◽

T. M. Girard ◽

V. Kozhurina-Platais ◽

R. A. Mendez ◽

W. F. Van Altena ◽

...

Keyword(s):

Reference Frame ◽

Proper Motion ◽

Systematic Errors ◽

Progress Report ◽

Model Choice ◽

Plate Model ◽

Field Independent ◽

The Status ◽

First Results ◽

Galaxy Model

We present the status of the Yale/San Juan Southern Proper Motion program (SPM) which is the southern hemisphere extension of the Lick Observatory Northern Proper Motion program with respect to faint galaxies (Platais et al., 1993). To date, measurements and reductions in the South Galactic Pole region comprising ≈ 1000 square-degrees on the sky have been finished. At this stage of the SPM program particular attention has been paid to the plate model choice along with an assessment of and accounting for systematic errors. For our establishing of a secondary reference frame we have noticed the presence of a potentially dangerous effect, so–called field–independent coma which is caused by lens decentering. We acknowledge the superb Hipparcos preliminary positions without which such analysis would be virtually impossible. The SPM data at the SGP region have also been used to constrain a multi–component Galaxy model. First results of this analysis are presented.

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Top-down control of reference frame alignment in directing attention from cue to target.

Converging operations in the study of visual selective attention. ◽

10.1037/10187-015 ◽

2004 ◽

pp. 415-437 ◽

Cited By ~ 3

Author(s):

Gordon D. Logan

Keyword(s):

Reference Frame ◽

Top Down ◽

Frame Alignment ◽

Directing Attention

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Brief communication: On calculating the sea-level contribution in marine ice-sheet models

The Cryosphere ◽

10.5194/tc-14-833-2020 ◽

2020 ◽

Vol 14 (3) ◽

pp. 833-840 ◽

Cited By ~ 3

Author(s):

Heiko Goelzer ◽

Violaine Coulon ◽

Frank Pattyn ◽

Bas de Boer ◽

Roderik van de Wal

Keyword(s):

Sea Level Rise ◽

Sea Level ◽

Ice Sheets ◽

Ice Sheet ◽

Ocean Water ◽

Ice Volume ◽

Isostatic Adjustment ◽

The Common

Abstract. Estimating the contribution of marine ice sheets to sea-level rise is complicated by ice grounded below sea level that is replaced by ocean water when melted. The common approach is to only consider the ice volume above floatation, defined as the volume of ice to be removed from an ice column to become afloat. With isostatic adjustment of the bedrock and external sea-level forcing that is not a result of mass changes of the ice sheet under consideration, this approach breaks down, because ice volume above floatation can be modified without actual changes in the sea-level contribution. We discuss a consistent and generalised approach for estimating the sea-level contribution from marine ice sheets.

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Holocene and Common Era sea level changes in the Makassar Strait, Indonesia

10.5194/cp-2019-63 ◽

2019 ◽

Author(s):

Maren Bender ◽

Thomas Mann ◽

Paolo Stocchi ◽

Dominik Kneer ◽

Tilo Schöne ◽

...

Keyword(s):

Sea Level ◽

Published Data ◽

Glacial Isostatic Adjustment ◽

Sea Level Changes ◽

Relative Sea Level ◽

Isostatic Adjustment ◽

Thousand Islands ◽

The Common ◽

Common Era ◽

Spermonde Archipelago

Abstract. Indonesia is a country composed of several thousand islands, many of them small, low-lying and densely inhabited. These are, in particular, subject to high risk of inundation due to future relative sea level changes. The Spermonde Archipelago, off the coast of Southwest Sulawesi, consists of more than 100 small islands. This study presents a dataset of 24 sea-level index points from fossil microatolls, surveyed on five islands in the Spermonde Archipelago and compares these new results with published data from the same region and with relative sea level predictions from different Glacial Isostatic Adjustment (GIA) models. The newly surveyed fossil microatolls are located around the islands of Tambakulu, Suranti (both ~ 60 km offshore of Makassar city), Bone Batang and Kodingareng Keke (both located in the center of the Archipelago) and Sanrobengi (located ~ 20 km south-southwest of Makassar). Results from the near- and mid-shelf islands indicate that relative sea level between 4 to 6 ka BP was less than one meter above present sea level. The only exception to this pattern is the heavily populated island of Barrang Lompo, where we record a significant subsidence when compared to the other islands. These new results support the conclusions from a previous dataset and are relevant to constrain late Holocene ice melting scenarios. Samples from the two outer islands (Tambakulu and Suranti) yielded ages spanning the Common Era that represent, to our knowledge, the first reported for the entire Southeast Asian region.

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The Combined Solution C04 for Earth Orientation Parameters Consistent with International Terrestrial Reference Frame 2005

Geodetic Reference Frames - International Association of Geodesy Symposia ◽

10.1007/978-3-642-00860-3_41 ◽

2009 ◽

pp. 265-270 ◽

Cited By ~ 97

Author(s):

Christian Bizouard ◽

Daniel Gambis

Keyword(s):

Reference Frame ◽

Terrestrial Reference Frame ◽

Earth Orientation Parameters ◽

Earth Orientation ◽

International Terrestrial Reference Frame ◽

Combined Solution ◽

Orientation Parameters

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Balancing under the high wire; a study into PTT antenna effects on the Common Guillemot Uria aalge

10.7287/peerj.preprints.2035 ◽

2016 ◽

Author(s):

Sylvie P Vandenabeele ◽

Emily LC Shepard ◽

Adam Grogan ◽

Richard Thompson ◽

Adrian C Gleiss ◽

...

Keyword(s):

Uria Aalge ◽

Common Guillemot ◽

Critical Effect ◽

In Captivity ◽

First Results ◽

The Common ◽

The Impact

External tags fitted to diving birds can affect them in many ways with the most critical effect being an increase in drag. The effects of transmitters can be even more acute due to the presence of a protruding aerial. The study assesses the impact of PTT antenna on the behaviour and energetics of device-equipped guillemots (Uria aalge) in captivity. Birds with antenna-devices appeared to consume about 20% more energy than non-antenna birds during the descent phase of the dive. The balance of the birds while diving or resting on the water also appeared to be compromised by the presence of an antenna. Based on these first results and because transmitters are one of the most common methods used to track animals, it appears critical to determine what impact these devices, and particularly antenna, can have on their bearers and try minimize it.

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Helmert transformation strategies in analysis of GPS position time-series

Geophysical Journal International ◽

10.1093/gji/ggaa371 ◽

2020 ◽

Vol 223 (2) ◽

pp. 973-992

Author(s):

Shiwei Guo ◽

Chuang Shi ◽

Na Wei ◽

Min Li ◽

Lei Fan ◽

...

Keyword(s):

Time Series ◽

Reference Frame ◽

Scale Factor ◽

Network Effect ◽

Satellite Orbits ◽

Surface Mass ◽

Helmert Transformation ◽

Position Time Series ◽

Transformation Parameters ◽

The Impact

SUMMARY Global positioning system (GPS) position time-series generated using inconsistent satellite products should be aligned to a secular Terrestrial Reference Frame by Helmert transformation. However, unmodelled non-linear variations in station positions can alias into transformation parameters. Based on 17 yr of position time-series of 112 stations produced by precise point positioning (PPP), we investigated the impact of network configuration and scale factor on long-term time-series processing. Relative to the uniform network, the uneven network can introduce a discrepancy of 0.7–1.1 mm, 21.3–27.5 μas and 1.3 mm in terms of root mean square (RMS) for the translation, rotation and scale factor (if estimated), respectively, no matter whether the scale factor is estimated. The RMS of vertical annual amplitude differences caused by such network effect reaches 0.5–0.6 mm. Whether estimating the scale factor mostly affects the Z-translation and vertical annual amplitude, leading to a difference of 1.3 mm when the uneven network is used. Meanwhile, the annual amplitude differences caused by the scale factor present different geographic location dependences over the north, east and up components. The seasonal signals derived from the transformation using the uniform network and without estimating scale factor have better consistency with surface mass loadings with more than 41 per cent of the vertical annual variations explained. Simulation studies show that 40–50 per cent of the annual signals in the scale factor can be explained by the aliasing of surface mass loadings. Another finding is that GPS draconitic errors in station positions can also alias into transformation parameters, while different transformation strategies have limited influence on identifying the draconitic errors. We suggest that the uniform network should be used and the scale factor should not be estimated in Helmert transformation. It is also suggested to perform frame alignment on PPP time-series, even though the used satellite products belong to a consistent reference frame, as the origin of PPP positions inherited from satellite orbits and clocks is not so stable during a long period. With Helmert transformation, the seasonal variations would better agree with surface mass loadings, and noise level of time-series is reduced.

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