27 Jul 2022
 | 27 Jul 2022

Noumea: A new multi-mission Cal/Val site for past and future altimetry missions?

Clémence Chupin, Valérie Ballu, Laurent Testut, Yann-Treden Tranchant, and Jérôme Aucan

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 example 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 campaign 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 campaign, 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.

Clémence Chupin et al.

Status: final response (author comments only)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on egusphere-2022-514', Christopher Watson, 15 Nov 2022
  • RC2: 'Comment on egusphere-2022-514', Anonymous Referee #2, 09 Jan 2023

Clémence Chupin et al.

Clémence Chupin et al.


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Short summary
Altimetry satellite are essential to monitor and understand sea level evolution around the world with rates accuracy of mm/year. But these systems must also be qualified and controlled, especially approaching the coast. Using long-term sea level time series from Noumea tide gauge (New-Caledonia) and in situ data collected during the GEOCEAN-NC campaign, we propose a method to re-analyse about twenty years of altimetry observations and re-address the question of sea level evolution in the lagoon.