Improving the precision of sea level data from satellite altimetry with high-frequency and regional Sea State Bias corrections

Passaro, M; Nadzir, ZA; Quartly, GD. 2018 Improving the precision of sea level data from satellite altimetry with high-frequency and regional Sea State Bias corrections. Remote Sensing of Environment, 218. 245-254. https://doi.org/10.1016/j.rse.2018.09.007

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Abstract/Summary

The sea state bias (SSB) is a large source of uncertainty in the estimation of sea level from satellite altimetry. It is still unclear to what extent it depends on errors in parameter estimations (numerical source) or to the wave physics (physical source). By improving the application of this correction we compute 20-Hz sea level anomalies that are about 30% more precise (i.e. less noisy) than the current standards. The improvement is two-fold: _rst we prove that the SSB correction should be applied directly to the 20-Hz data (12 to 19% noise decrease); secondly, we show that by recomputing a regional SSB model (based on the 20-Hz estimations) even a simple parametric relation is su_cient to further improve the correction (further 15 to 19% noise decrease). We test our methodology using range, wave height and wind speed estimated with two retrackers applied to Jason-1 waveform data: the MLE4 retracked-data available in the Sensor Geophysical Data Records of the mission and the ALES retracked-data available in the OpenADB repository (https://openadb.dg_.tum.de/). The regional SSB models are computed parametrically by means of a crossover analysis in the Mediterranean Sea and North Sea. Correcting the high-rate data for the SSB reduces the correlation between retracked parameters. Regional variations in the proposed models might be due to di_erences in wave climate and remaining sea-state dependent residual errors. The variations in the empirical model with respect to the retracker used recall the need for a speci_c SSB correction for any retracker. This study, while providing a signi_cantly more precise solution to exploit high-rate sea level data, calls for a re-thinking of the SSB correction in both its physical and numerical component, gives robustness to previous theories and provides an immediate improvement for the application of satellite altimetry in the regions of study.

Item Type: Publication - Article
Divisions: Plymouth Marine Laboratory > Science Areas > Earth Observation Science and Applications
Depositing User: Kim Hockley
Date made live: 26 Sep 2018 11:57
Last Modified: 08 Nov 2018 10:09
URI: http://plymsea.ac.uk/id/eprint/8005

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