Revised uncertainties of the Global Mean Sea Level biases between the Topex & Jasons reference missions

Adrien Guerou (CLS, France)


Lionel Zawadzki (CNES, France); Matthias Raynal (CLS, France); Michaël Ablain (Magellium, France); Rémi Jugier (Magellium, France)

Event: 2020 Ocean Surface Topography Science Team Meeting (virtual)

Session: Quantifying Errors and Uncertainties in Altimetry data

Presentation type: Type Forum

The Global Mean Seal Level (GMSL) record is currently built from the four successive altimetry reference missions: Topex-A/B, Jason-1, Jason-2 and Jason-3. Specific periods called “tandem phases” allow to calibrate each mission with its predecessor to ensure a continuous GMSL record. The inter-mission GMSL biases are derived during these tandem phases. However, uncertainties remain and need to be characterized.

Ablain et al. (2019) offers an error budget approach to characterize the uncertainties on the GMSL measurements and trend estimations, considering all potential sources of errors, including the inter-missions’ biases. However, their value of 0.5 mm (1-sigma) used for the all the missions can be discussed.

In this presentation we revised the method to estimate the uncertainties of the GMSL inter-mission biases and estimate new values for the four altimetry reference missions. We found new estimations of the GMSL inter-mission biases that are more representative of the true GMSL records, still consistent with the values used in Ablain et al. (2019). We also analyze the impact of the revised inter-mission bias uncertainties on the GMSL error budget and quantified the new uncertainties of the GMSL measurements with a focus on its trend estimation.
Adrien Guerou