The Role of GNSS Vertical Velocities to Correct Estimates of Sea Level Rise from Tide Gauge Measurements in Greece |
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Authors: | Stylianos Bitharis Christos Pikridas Aristeidis Fotiou Dimitrios Rossikopoulos Harald Schuh |
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Institution: | 1. Department of Geodesy and Surveying, Aristotle University of Thessaloniki, Thessaloniki, Greece;2. Department of Geodesy, German Research Centre for Geosciences, Potsdam, Germany;3. School VI Planning Building Environment, Institute of Geodesy and Geoinformation Science, Technical University of Berlin, Berlin, Germany |
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Abstract: | In this study, we show how the Global Navigation Satellite System (GNSS)-derived vertical velocities contribute to the correction of tide gauge (TG) measurements used for the sea level rise estimation in Greece. Twelve sites with records of local sea level heights are processed in order to estimate their trend. Certain error sources related to TGs, e.g. equipment changes, data noise, may lead to biased or erroneous estimations of the sea level height. Therefore, it would be preferred to follow a robust estimation technique in order to detect and reduce outlier effects. The geocentric sea level rise is estimated by taking into account the land vertical motion of co-located GNSS permanent stations at the Hellenic area. TGs measure the height of the water relative to a monitored geodetic benchmark on land. On the other hand, using GNSS-based methods the vertical land motion can be derived. By means of extended models fitted to the GNSS time-series position, obtained from seven years of continuous data analysis, periodic signals are well described. The synergy of the two co-located techniques results in the correction of TG relative sea level heights taking into account the GNSS vertical velocities and consequently obtaining the conversion to absolute (geocentric) sea level trend. |
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Keywords: | GNSS permanent stations ITRF2014 tide gauges vertical velocities |
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