Quantifying the impact of wave dynamics, tidal influence, and bathymetric variations on the performance of Coastal Altimetry: a case study in the Indonesian seas

Coastal altimetry datasets are essential to understand coastal dynamics, using sea level variability as a proxy. Yet, their level of accuracy is influenced by, among others,  the condition of bathymetry, tides, and waves in the region. Until now, only a few studies assessed the contribution of these oceanographic conditions, especially in regions with a challenging coastal environment, such as the Indonesian seas.  This study aims to assess the individual and combined impacts of the aforementioned factors on the accuracy level of three coastal altimetry datasets (ALES, X-TRACK, and X-TRACK/ALES). Focusing on the Indonesian seas, we seek to provide insights into challenges specifically posed by these diverse, dynamic coastal settings. Utilizing a selection of statistical analysis, we combine three said coastal altimetry datasets with different numerical and empirical tidal, bathymetry, and wave models to isolate and evaluate the impact of bathymetry variation, tidal regime, and wave dynamics on the performance of coastal altimetry datasets, in comparison to a selection of tide gauges. We then classify the contributions of different factors to coastal altimetry datasets' accuracy. Preliminary results reveal different patterns of influences from each oceanographic condition in three different regions on the Indonesian seas. We suggest this could aid coastal (less than 10 km) altimetry data processing, particularly in regions characterized by intricate coastal dynamics. The outcome underlines the necessity to take the interplay between bathymetry, tides, and waves into consideration when processing coastal altimetry datasets.