. (2010). Sea level trends in the Southern Ocean over the last century from historical data.
Abstract: EGU Meeting, 3-7 May 2010, Vienna.
Programme: 688
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Maraldi Claire, Lyard Florent, Testut Laurent, Coleman Richard, . (2011). Energetics of internal tides around the Kerguelen Plateau from modeling and altimetry
. 0148-0227, 116(C6), C06004–.
Abstract: A barotropic tidal model, with a parameterization term to account for the internal wave drag energy dissipation, is used to examine areas of possible M2 internal tide generation in the Kerguelen Plateau region. Barotropic energy flux and a distribution of wave drag dissipation are computed. The results suggest important conversion of barotropic energy into baroclinic tide generation over the northern Kerguelen Plateau shelf break, consistent with a theoretical criterion based on ocean stratification, tidal forcing frequency, and bathymetric gradients. The sea surface height signatures of time-coherent internal tides are studied using TOPEX/Poseidon and Jason-1 altimeter data, whose ascending tracks cross nearly perpendicular to the eastern and western Kerguelen Plateau shelf break. Oscillations of a few centimeters associated with phase-locked internal tides propagate away from the plateau over distances of several hundred kilometers with a ~110 km wavelength. When reaching the frontal area of the Antarctic Circumpolar Current, the internal tide cannot be identified because of the aliasing of mesoscale variability into the same alias band as M2. Finally, using altimeter data, we estimate the M2 barotropic tidal power converted through the internal tide generation process. We find consistent values with the barotropic model parameterization estimation, which is also in good agreement with global internal tide model estimates. Combined with modeling, this study has shown that altimetry can be used to estimate internal tide dissipation.
Keywords: internal tides, Kerguelen Plateau, altimetry, barotropic tides, 4560 Oceanography: Physical: Surface waves and tides (1222), 4219 Oceanography: General: Continental shelf and slope processes (3002), 4223 Oceanography: General: Descriptive and regional oceanography, 4262 Oceanography: General: Ocean observing systems, 4534 Oceanography: Physical: Hydrodynamic modeling,
Programme: 688
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. (2012). Performance of modern tide gauges: towards mm-level accuracyJF
. Sci. Mar., .
Abstract: Considerable efforts are being made worldwide to upgrade tide gauge networks using new technologies. Because of the unique location of the Kerguelen Islands, the measurement of sea level there has received particular attention, with up to four systems equipped with modern sensors functioning simultaneously (two pressure tide gauges, a radar tide gauge, and a GPS-equipped buoy). We analysed and compared the sea level data obtained with these systems from 2003 to 2010, together with a time series of tide pole observations. This is the first time that a multi-comparison study with tide gauges has been undertaken over such a long time span and that the stability of modern radar tide gauges has been examined. The multi-comparison enabled us to evaluate the performance of the tide gauges in several frequency ranges, identify errors and estimate their magnitude. The drift of the pressure sensors (up to 8.0 mm/yr) was found to be one of the most relevant sources of systematic error. Other sources of difference such as clock drift, scale error and different locations of the instruments were also detected. After correcting the time series of sea level for these errors we estimated an upper bound for the radar instrumental error in field condition at ~0.3 cm.
Keywords: radar; pressure gauges; sea level changes; sea level measurement; tide gauges; Kerguelen Islands; GPS buoy,
Programme: 688
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Fund F, Perosanz F, Testut L, Loyer S, . (2013). An Integer Precise Point Positioning technique for sea surface observations using a GPS buoy
. Adv Space Res, 51(8), 1311–1322.
Abstract: GPS data dedicated to sea surface observation are usually processed using differential techniques. Unfortunately, the precision of resulting kinematic positions is baseline-length dependent. So, high precision sea surface observations using differential GPS techniques are limited to coasts, lakes, and rivers. Recent improvements in GPS satellite products (orbits, clocks, and phase biases) make phase ambiguity fixing at the zero difference level achievable and opens up the observation of the sea surface without geographical constraints. This paper recalls the concept of the Integer Precise Point Positioning technique and discusses the precision of GPS buoy positioning. A sequential version of the GINS software has been implemented to achieve single epoch GPS positioning. We used 1 Hz data from a two week GPS campaign conducted in the Kerguelen Islands. A GPS buoy has been moored close to a radar gauge and 90 m away from a permanent GPS station. This infrastructure offers the opportunity to compare both kinematic Integer Precise Point Positioning and classical differential GPS positioning techniques to in situ radar gauge data. We found that Precise Point Positioning results are not significantly biased with respect to radar gauge data and that horizontal time series are consistent with differential processing at the sub-centimetre precision level. Nevertheless, standard deviations of height time series with respect to radar gauge data are typically [45] cm. The dominant driver for noise at this level is attributed to errors in tropospheric estimates which propagate into position solutions.
Keywords: GPS, Ambiguity fixing, Tropospheric delays, Buoy, Radar gauge,
Programme: 688
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Testut L, Birol F, Delebecque C, . (2012). Regional Tidal Modeling and Evaluation of Jason-2 Tidal Geophysical Correction
. Marine Geodesy, 35(sup1), 299–313.
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. (2011). 0373-3629, 8(777), 14–1.
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. (2011). Dynamics of Mertz Glacier and its ice tongue, East Antarctica: implications of its calving and changes at various time scales.
Abstract: International Symposium on Changes in Glaciers and Ice Sheets, 28 Jul. – 2 Aug. 2013, Beijing (China).
Programme: 688
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Mayet C, Testut L, Legresy B, Lescarmontier L, Lyard F, . (2013). High-resolution barotropic modeling and the calving of the Mertz Glacier, East Antarctica
. J. Geophys. Res. Oceans, 118(10), 5267–5279.
Keywords: 0732 Icebergs, 0758 Remote sensing, 4512 Currents, 4534 Hydrodynamic modeling, 9310 Antarctica, barotropic, calving, icebergs, Mertz Glacier, model,
Programme: 688
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. (2013). Measuring sea-level with GPS-equipped buoys: A multi-instruments experiment at Aix Island. International Hydrographic Review, , 27–38.
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Delebecque C., F. Lyard, F. Birol, N. Ayoub, L. Testut, L. Roblou. (2013). Using CTOH tidal constants for coastal studies.
Abstract: 7th Coastal Altimetry Workshop, 7-8 Oct. 2013. Boulder (USA).
Programme: 688
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