Abstract's details
Limiting factors of the altimetry observing system to the Global Mean Sea Level monitoring accuracy
CoAuthors
Event: 2022 Ocean Surface Topography Science Team Meeting
Session: Quantifying Errors and Uncertainties in Altimetry data
Presentation type: Type Oral
Contribution: PDF file
Abstract:
The satellite altimetry observing system has proved since 1992 and the TopEx/Poseidon mission its capacity to monitor the sea level rise induced by climate change over the globe. On the basis of this accurate monitoring of sea level, space agencies developed climate data records that are now commonly used by scientists to study climate change and by stakeholders to support their decisions on climate change adaptation and mitigation strategies. For science users as for stakeholders it is essential to quantify the exact stability and accuracy of the altimetry-based climate indicators as they are at the basis of their analysis and assessments.
In this context, we will present the latest released of the Global Mean Sea Level (GMSL) climate data record produced by the French space agency CNES and distributed on the AVISO+ website. This data record is based on reprocessed along-track data, so-called L2P21 data, of the reference missions TopEx-Poseidon, Jason-1/-2 and -3. It is delivered with an estimate of the associated uncertainties following the method developed in Ablain et al. (2019). Based on an updated version of the uncertainty budget of TopEx and Jasons altimetry missions, presented in Guerou et al. (2022, submitted), we will demonstrate that we achieve stability performances of ± 0.3 mm/yr at the 5-95% confidence level for the GMSL trend over the full data record and ± 0.06 mm/yr^2 (5-95% C.L) for the GMSL acceleration. In addition we will present the relative contribution of each uncertainty budget contributor (i.e., the altimeter, the radiometer, the orbit determination, the geophysical corrections) to the total GMSL uncertainty. Thanks to such analysis, we will identify the current limiting factors to the GMSL monitoring stability and accuracy and suggest key topics of investigations to help the altimetry community to improve the GMSL accuracy in the future.
In this context, we will present the latest released of the Global Mean Sea Level (GMSL) climate data record produced by the French space agency CNES and distributed on the AVISO+ website. This data record is based on reprocessed along-track data, so-called L2P21 data, of the reference missions TopEx-Poseidon, Jason-1/-2 and -3. It is delivered with an estimate of the associated uncertainties following the method developed in Ablain et al. (2019). Based on an updated version of the uncertainty budget of TopEx and Jasons altimetry missions, presented in Guerou et al. (2022, submitted), we will demonstrate that we achieve stability performances of ± 0.3 mm/yr at the 5-95% confidence level for the GMSL trend over the full data record and ± 0.06 mm/yr^2 (5-95% C.L) for the GMSL acceleration. In addition we will present the relative contribution of each uncertainty budget contributor (i.e., the altimeter, the radiometer, the orbit determination, the geophysical corrections) to the total GMSL uncertainty. Thanks to such analysis, we will identify the current limiting factors to the GMSL monitoring stability and accuracy and suggest key topics of investigations to help the altimetry community to improve the GMSL accuracy in the future.