External Evaluation of the Terrestrial Reference Frame: Report of the Task Force of the IAG Sub-commission 1.2

Collilieux, Xavier; Altamimi, Z.; Argus, Donald F.; Boucher, C.; Dermanis, Athanasios; Haines, Bruce; Herring, T. A.; Kreemer, C.; Lemoine, F. G.; Ma, C.; MacMillan, D. S.; Mäkinen, Jaakko; Métivier, Laurent; Ries, John; Teferle, Felix Norman; Wu, Xiaoping

doi:10.1007/978-3-642-37222-3_25

Cited by 22 publications

(23 citation statements)

References 28 publications

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“…The trend of +0.03 ppb yr −1 (GPS scale increasing with respect to ITRF2008) corresponds to only +0.2 mm yr −1 at the Earth's surface. This small relative drift is close to the estimated error of ITRF2008 Argus, 2012;Collilieux et al, 2014], implying we cannot identify which of the underlying geodetic techniques (VLBI/SLR or GPS) is preferred for long-term scale stability. Though we can discern some small interannual variations in the time series, there is no evidence of the abrupt (∼1 ppb) scale instabilities which originally implicated the GPS satellite antenna models as significant error sources [Ge et al, 2005].…”

Section: Results: Scalementioning

confidence: 78%

“…As with the equatorial (X, Y) components, these long-term differences are in keeping with the uncertainty of ITRF2008 [Wu et al, 2011;Argus, 2012;Collilieux et al, 2014], implying it is not possible on this basis to identify which solution is preferred.…”

Section: Results: Origin and Geocenter Motionmentioning

confidence: 99%

“…Driven in large measure by the demands of sea level monitoring, international initiatives are underway to improve the stability of the TRF to the 0.1 mm yr −1 level [Plag and Pearlman, 2009;NRC, 2010;Merkowitz et al, 2012]. This goal represents a factor-of-five improvement over the present state of the art [Wu et al, 2011;Collilieux et al, 2014].…”

Section: Introductionmentioning

confidence: 99%

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Realizing a terrestrial reference frame using the Global Positioning System

et al. 2015

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We describe a terrestrial reference frame (TRF) realization based on Global Positioning System (GPS) data alone. Our approach rests on a highly dynamic, long‐arc (9 day) estimation strategy and on GPS satellite antenna calibrations derived from Gravity Recovery and Climate Experiment and TOPEX/Poseidon low Earth orbit receiver GPS data. Based on nearly 17 years of data (1997–2013), our solution for scale rate agrees with International Terrestrial Reference Frame (ITRF)2008 to 0.03 ppb yr−1, and our solution for 3‐D origin rate agrees with ITRF2008 to 0.4 mm yr−1. Absolute scale differs by 1.1 ppb (7 mm at the Earth's surface) and 3‐D origin by 8 mm. These differences lie within estimated error levels for the contemporary TRF.

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Section: Results: Scalementioning

confidence: 78%

Section: Results: Origin and Geocenter Motionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Realizing a terrestrial reference frame using the Global Positioning System

et al. 2015

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“…Reference frame errors are adopted from a recent review, which concluded that the International Terrestrial Reference Frame (ITRF) is stable along each axis to better than 0.5 mm/year (z-drift) and has a scale error of less than 0.3 mm/year [27]. The uncertainty on the geoid change associated with GIA is very small and has a value of typically 0.03 mm/year.…”

Section: Analysis Of the Norwegian Tide Gaugesmentioning

confidence: 99%

“…The reference frame uncertainties applied in our tide-gauge analysis are 0.5 mm/year and 0.3 mm/year for the z-drift and scale rate, respectively [27]. These values are computed for ITRF2008, but we assume that the combined uncertainty for ITRF2005 and CSR95 is of the same order.…”

Section: Analysis Of Altimetry Data From the Norwegian Coastmentioning

confidence: 99%

Observed Sea-Level Changes along the Norwegian Coast

Breili

Simpson

Nilsen

2017

JMSE

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Norway's national sea level observing system consists of an extensive array of tide gauges, permanent GNSS stations, and lines of repeated levelling. Here, we make use of this observation system to calculate relative sea-level rates and rates corrected for glacial isostatic adjustment (GIA) along the Norwegian coast for three different periods, i.e., 1960 to 2010, 1984 to 2014, and 1993 to 2016. For all periods, the relative sea-level rates show considerable spatial variations that are largely due to differences in vertical land motion due to GIA. The variation is reduced by applying corrections for vertical land motion and associated gravitational effects on sea level. For 1960 to 2010 and 1984 to 2014, the coastal average GIA-corrected rates for Norway are 2.0 ± 0.6 mm/year and 2.2 ± 0.6 mm/year, respectively. This is close to the rate of global sea-level rise for the same periods. For the most recent period, 1993 to 2016, the GIA-corrected coastal average is 3.5 ± 0.6 mm/year and 3.2 ± 0.6 mm/year with and without inverse barometer (IB) corrections, respectively, which is significantly higher than for the two earlier periods. For 1993 to 2016, the coastal average IB-corrected rates show broad agreement with two independent sets of altimetry. This suggests that there is no systematic error in the vertical land motion corrections applied to the tide-gauge data. At the same time, altimetry does not capture the spatial variation identified in the tide-gauge records. This could be an effect of using altimetry observations off the coast instead of directly at each tide gauge. Finally, we note that, owing to natural variability in the climate system, our estimates are highly sensitive to the selected study period. For example, using a 30-year moving window, we find that the estimated rates may change by up to 1 mm/year when shifting the start epoch by only one year.

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KALREF—A Kalman filter and time series approach to the International Terrestrial Reference Frame realization

Abbondanza

Altamimi

et al. 2015

JGR Solid Earth

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The current International Terrestrial Reference Frame is based on a piecewise linear site motion model and realized by reference epoch coordinates and velocities for a global set of stations. Although linear motions due to tectonic plates and glacial isostatic adjustment dominate geodetic signals, at today's millimeter precisions, nonlinear motions due to earthquakes, volcanic activities, ice mass losses, sea level rise, hydrological changes, and other processes become significant. Monitoring these (sometimes rapid) changes desires consistent and precise realization of the terrestrial reference frame (TRF) quasi-instantaneously. Here, we use a Kalman filter and smoother approach to combine time series from four space geodetic techniques to realize an experimental TRF through weekly time series of geocentric coordinates. In addition to secular, periodic, and stochastic components for station coordinates, the Kalman filter state variables also include daily Earth orientation parameters and transformation parameters from input data frames to the combined TRF. Local tie measurements among colocated stations are used at their known or nominal epochs of observation, with comotion constraints applied to almost all colocated stations. The filter/smoother approach unifies different geodetic time series in a single geocentric frame. Fragmented and multitechnique tracking records at colocation sites are bridged together to form longer and coherent motion time series. While the time series approach to TRF reflects the reality of a changing Earth more closely than the linear approximation model, the filter/smoother is computationally powerful and flexible to facilitate incorporation of other data types and more advanced characterization of stochastic behavior of geodetic time series.

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External Evaluation of the Terrestrial Reference Frame: Report of the Task Force of the IAG Sub-commission 1.2

Cited by 22 publications

References 28 publications

Realizing a terrestrial reference frame using the Global Positioning System

Realizing a terrestrial reference frame using the Global Positioning System

Observed Sea-Level Changes along the Norwegian Coast

KALREF—A Kalman filter and time series approach to the International Terrestrial Reference Frame realization

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