ORCID Profile
0000-0002-9781-8508
Current Organisation
École Nationale Supérieure de Techniques Avancées Bretagne
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Publisher: Copernicus GmbH
Date: 27-07-2022
DOI: 10.5194/EGUSPHERE-2022-514
Abstract: Abstract. To better understand sea level evolution in coastal areas, one needs to link and combine global observations from altimetry satellites with the scattered but long-term tide gauges measurements. In New-Caledonia, the Noumea lagoon is an ex le of this challenge as altimetry, coastal tide gauge and vertical land movements from Global Navigation Satellite Systems (GNSS) do not provide consistent information. The GEOCEAN-NC 2019 field c aign tries to address this question with the deployments of in situ instruments in the lagoon, with a particular interest for the crossing point of three different altimetry tracks (Jason/Sentinel-3a). Thanks to GNSS buoy and pressure gauge observations, we propose a method to virtually transfer the Noumea tide gauge offshore, to obtain a long-term sea surface height (SSH) time series at the altimetry crossover point. We also reprocess the 20 Hz along-track data from Jason and Sentinel-3a Geophysical Data Records (GDR) with the best correction parameters in the area. These two SSH time series (i.e. in situ and altimetry) allow us to compute the altimeter biases time series over the entire Jason and Sentinel-3a period. With our 3 weeks field c aign, we reanalyse about 20 years of altimetry observations and find inter-mission biases consistent with historical calibration sites, thus further increasing our knowledge of the local sea level rise in this region. This offers many opportunities to develop Cal/Val activities in the lagoon, which is also the subject of several experiments for the scientific calibration phase of the future large-swath altimetry mission SWOT.
Publisher: Copernicus GmbH
Date: 22-08-2023
Abstract: Abstract. Today, monitoring the evolution of sea level in coastal areas is of importance, since almost 11 % of the world's population lives in low-lying areas. Reducing uncertainties in sea level estimates requires a better understanding of both altimetry measurements and local sea level dynamics. In New Caledonia, the Nouméa lagoon is an ex le of this challenge, as altimetry, coastal tide gauge, and vertical land motions from global navigation satellite systems (GNSSs) do not provide consistent information. The GEOCEAN-NC 2019 field c aign addresses this issue with deployments of in situ instruments in the lagoon (GNSS buoy, pressure gauge, etc.), with a particular focus on the crossover of one Jason-series track and two Sentinel-3A missions tracks. In this study, we propose a method to virtually transfer the Nouméa tide gauge at the altimetry crossover point, using in situ data from the field c aign. Following the philosophy of calibration and validation (Cal/Val) studies, we derive absolute altimeter bias time series over the entire Jason and Sentinel-3A periods. Overall, our estimated altimeter mean biases are slightly larger by 1–2 cm compared to Corsica and Bass Strait results, with inter-mission biases in line with those of Bass Strait site. Uncertainties still remain regarding the determination of our vertical datum, only constrained by the three days of the GNSS buoy deployment. With our method, we are able to re-analyse about 20 years of altimetry observations and derive a linear trend of −0.2 ± 0.1 mm yr−1 over the bias time series. Compared to previous studies, we do not find any significant uplift in the area, which is more consistent with the observations of inland permanent GNSS stations. These results support the idea of developing Cal/Val activities in the lagoon, which is already the subject of several experiments for the scientific calibration phase of the SWOT wide-swath altimetry mission.
Location: France
Location: France
No related grants have been discovered for Clémence CHUPIN.