Towards the optimisation of altimetry corrections for improved ocean tide modelling

Abstract

 Ocean tide models are created for a variety of applications ranging from serving as an altimetry correction to being applied as numerical model boundary forcings. DGFI-TUM’s Empirical Ocean Tide (EOT) and NASA's Goddard Ocean Tide (GOT) models are derived based on sea-level anomalies (SLA) from multi-mission satellite altimetry. All SLA measurements are corrected for geophysical effects, which means that the estimations of tides are reliant on the accuracy of these respective correction models. Within these corrections, tidal signals or frequencies that align closely with those of tides may be present which have clear downstream implications on the derivation of ocean tides from along-track satellite altimetry. In this study, the two different ocean tide models have been used as they utilise different techniques for tidal estimations but both are dependent on the chosen altimetric corrections. In the global EOT20 model, altimetric corrections played an important role in improving the accuracy of the model in the coastal region. However, these coastal optimised corrections may be influencing the open ocean performance of the model. This has meant that further investigations should take place to describe the best set of altimetry corrections to optimise the accuracy of tide estimations made by the EOT model in all regions. Additionally, several versions of the GOT model have been developed to contrast the influences of the different corrections both for the open ocean and coastal regions. In this presentation, the impact of different geophysical corrections (e.g. ionospheric, internal tide and mesoscale) are presented with the aim to conclude on the optimal set-up of these corrections for empirical tide models. Results here are shown in different experiments that include assessing the impacts of ocean tide estimations on both along-track as well as modelled estimations.