The contribution of local gravimetric geoid models to the calibration of satellite altimetry data and an outlook of the latest GOCE GGM performance in Gavdos

Tziavos, I. N.; Vergos, Georgios S.; Mertikas, Stelios P.; Daskalakis, A.; Grigoriadis, Vassilios; Tripolitsiotis, Achilles

doi:10.1016/j.asr.2012.06.013

Cited by 17 publications

(4 citation statements)

References 49 publications

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“…3). The Gravity field and steady-state Ocean Circulation Explorer (GOCE), ACCEPTED MANUSCRIPT ACCEPTED MANUSCRIPT 9 (Tziavos et al 2013) and the Rio MED (Rio et al 2014) models have been used for the determination of the Mean Dynamic Topography (Mertikas et al 2011). The applied methodology for the altimeter calibration is outlined in Table 2 (Mertikas et al 2010(Mertikas et al , 2011.…”

Section: Calibration Of Saral/altikamentioning

confidence: 99%

“…Geoid models have been estimated for the wider area of the Gavdos, following the remove-compute-restore method, while the least squares collocation with errors has been used to predict geoid heights from gravity anomalies (Tziavos et al 2013). The two geoid models have a mean difference of 1.9cm and a standard deviation of ±1.4 cm (Fig.4).…”

Section: Calibration Of Saral/altikamentioning

confidence: 99%

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First Calibration Results for the SARAL/AltiKa Altimetric Mission Using the Gavdos Permanent Facilities

et al. 2015

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Downloaded by [University of California, San Diego] at 02:50 13 June 2015 ACCEPTED MANUSCRIPT ACCEPTED MANUSCRIPT 2 This work presents the first calibration results for the SARAL/AltiKa altimetric mission using the Gavdos permanent calibration facilities. The results are covering one year of altimetric observations from April, 2013 till March 2014, and include 11 calibration values for the altimeter bias. The reference ascending orbit No. 571 of SARAL/AltiKa has been used for this altimeter assessment. This satellite pass is coming from south and nears Gavdos, where it finally passes through its west coastal tip, only 6 km off the main calibration location. The selected calibration regions in the south sea of Gavdos range from about 8 km to 20 km south off the point of closest approach. Several reference surfaces have been chosen for thisaltimeter evaluation based on gravimetric, but detailed regional geoid, as well as combination of it with other altimetric models. Based on these observations and the gravimetric geoid model, the altimeter bias for the SARAL/AltiKa is determined as mean value of -46mm ±10mm, and a median of -42mm ±10mm, using GDR-T data at 40 Hz rate. A preliminary cross-over analysis of the sea surface heights at a location south of Gavdos showed that SARAL/AltiKa measure less than Jason-2 by 4.6 cm. These bias values are consistent with those provided by Corsica, Harvest, and Karavatti Cal/Val sites. The wet troposphere and the ionosphere delay values of satellite altimetric measurements are also compared against in-situ observations (-5 mm difference in wet troposphere and almost the same for the ionosphere) determined by a local array of permanent GNSS receivers, and meteorological sensors.

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Section: Calibration Of Saral/altikamentioning

confidence: 99%

Section: Calibration Of Saral/altikamentioning

confidence: 99%

First Calibration Results for the SARAL/AltiKa Altimetric Mission Using the Gavdos Permanent Facilities

et al. 2015

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“…Then, this value is transferred to open sea in the calibrating regions using reference models. Detailed and precise models have been constructed for the mean dynamic topography ( ) and geoid undulation ( ) in this region [28]. Models are often being validated as a matter of usual practice by means of dedicated boat campaigns.…”

Section: Sea-surface Calibrationmentioning

confidence: 99%

Absolute Calibration of the European Sentinel-3A Surface Topography Mission over the Permanent Facility for Altimetry Calibration in west Crete, Greece

et al. 2018

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This work presents calibration results for the altimeter of Sentinel-3A Surface Topography Mission as determined at the Permanent Facility for Altimetry Calibration in west Crete, Greece. The facility has been providing calibration services for more than 15 years for all past (i.e., Envisat, Jason-1, Jason-2, SARAL/AltiKa, HY-2A) and current (i.e., Sentinel-3A, Sentinel-3B, Jason-3) satellite altimeters. The groundtrack of the Pass No.14 of Sentinel-3A ascends west of the Gavdos island and continues north to the transponder site on the mountains of west Crete. This pass has been calibrated using three independent techniques activated at various sites in the region: (1) the transponder approach for its range bias, (2) the sea-surface method for the estimation of altimeter bias for its sea-surface heights, and (c) the cross-over analysis for inspecting height observations with respect to Jason-3. The other Pass No.335 of Sentinel-3A descends from southwest of Crete to south and intersects the Gavdos calibration site. Additionally, calibration values for this descending pass are presented, applying sea-surface calibration and crossover analysis. An uncertainty analysis for the altimeter biases derived by the transponder and by sea-surface calibrations is also introduced following the new standard of Fiducial Reference Measurements.

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“…The end of the GOCE mission in 2013 resulted in an abundance of gradiometric observations offering unprecedented high-accuracy information for the medium frequencies of the gravity field spectrum. Apart from the obvious improvements that GOCE offered to gravity field and geoid approximation (Andritsanos et al 2015;Carrion et al 2015;Gruber et al 2011;Hirt et al 2011;Š prlák et al 2012;Vergos et al 2014;Tziavos et al 2016) and the contribution to mapping the dynamic ocean topography and ocean circulation (Albertella et al 2012;Tziavos et al 2013), an emerging issue is the unification of local vertical datums (LVDs) to a World Height System (WHS). Height System Unification (HSU) refers in essence to the determination of vertical offsets between the various vertical datums, either within the limits of a country, regional ones or on a world scale between countries and continents.…”

Section: Introductionmentioning

confidence: 99%

Preliminary results of GOCE-based height system unification between Greece and Turkey over marine and land areas

et al. 2017

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The unification of local vertical datums (LVDs) at a country-wide scale has gained significant attention lately due to the availability of GOCE-based global geopotential models (GGMs) and the unprecedented geoid height accuracies offered. Within a single country, several LVDs may be used, especially in the case of islandic nations. Therefore, the unification of all of them to a single nationwide LVD is of utmost importance. The same holds for neighboring countries, where the unification of their vertical datums is necessary as a tool of engineering, cross-border collaboration and environmental and risk management projects. The aforementioned set the main scope of the present study, which focuses on the use of GOCE and GOCE/GRACE GGMs in order to investigate the offsets between the Greek and Turkish LVDs. First an evaluation of the latest release 5 GOCE GGMs is carried out, either to their maximum degree or through spectral enhancement with EGM208 and topographic effects. Then, the geopotential value for the Greek and Turkish LVDs is performed, along with different estimates for the marine area of the Aegean Sea where several islands and isles exist with each one realizing its own LVD. The relative offset between the two LVDs was determined and used to provide a direct link between the Greek and Turkish LVDs with the IAG conventional value recently proposed as a global WHS. From the results achieved it was concluded that the spectrally enhanced GOCE GGMs reduce the standard deviation of the differences with GPS/levelling data by 2-4 cm over Turkey and 2 cm for mainland Greece. In terms of the zero-level geopotential determination, the LVD of the Greek mainland is 64.9 cm below the IAG conventional value, while that of Turkey is 9.6 cm above. Finally, it is concluded that in practice each Greek island realizes its own LVD with offsets between them as large as 35 cm. Despite that fact, the spectrally enhanced GOCE GGMs and in particular

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The contribution of local gravimetric geoid models to the calibration of satellite altimetry data and an outlook of the latest GOCE GGM performance in Gavdos

Cited by 17 publications

References 49 publications

First Calibration Results for the SARAL/AltiKa Altimetric Mission Using the Gavdos Permanent Facilities

First Calibration Results for the SARAL/AltiKa Altimetric Mission Using the Gavdos Permanent Facilities

Absolute Calibration of the European Sentinel-3A Surface Topography Mission over the Permanent Facility for Altimetry Calibration in west Crete, Greece

Preliminary results of GOCE-based height system unification between Greece and Turkey over marine and land areas

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