North SEAL: a new dataset of sea level changes in the North Sea from satellite altimetry

• Published in: Earth system science data Vol. 13; no. 8; pp. 3733 - 3753
• Main Authors: Dettmering, Denise, Müller, Felix L, Oelsmann, Julius, Passaro, Marcello, Schwatke, Christian, Restano, Marco, Benveniste, Jérôme, Seitz, Florian
• Format: Journal Article
• Language: English
• Published: Katlenburg-Lindau Copernicus GmbH 02.08.2021; Copernicus Publications
• Subjects: Altimeters; Anomalies; Climate change; Coastal environments; Coastal zone; Coasts; Consistency; Correlation; Data analysis; Datasets; Economics; Finite element method; Investigations; Offshore; Outliers (statistics); Regions; Satellite altimetry; Satellites; Sea level; Sea level anomalies; Sea level changes; Sea level trends; Spatial variability; Spatial variations; Tide gauges; Time series; Trends; North Sea; Baltic Sea
• ISSN: 1866-3516; 1866-3508; 1866-3516
• DOI: 10.5194/essd-13-3733-2021

Information on sea level and its temporal and spatial variability is of great importance for various scientific, societal, and economic issues. This article reports about a new sea level dataset for the North Sea (named North SEAL) of monthly sea level anomalies (SLAs), absolute sea level trends, and amplitudes of the mean annual sea level cycle over the period 1995–2019. Uncertainties and quality flags are provided together with the data. The dataset has been created from multi-mission cross-calibrated altimetry data preprocessed with coastal dedicated approaches and gridded with an innovative least-squares procedure including an advanced outlier detection to a 6–8 km wide triangular mesh. The comparison of SLAs and tide gauge time series shows good consistency, with average correlations of 0.85 and maximum correlations of 0.93. The improvement with respect to existing global gridded altimetry solutions amounts to 8 %–10 %, and it is most pronounced in complicated coastal environments such as river mouths or regions sheltered by islands. The differences in trends at tide gauge locations depend on the vertical land motion model used to correct relative sea level trends. The best consistency with a median difference of 0.04±1.15 mm yr−1 is reached by applying a recent glacial isostatic adjustment (GIA) model. With the presented sea level dataset, for the first time, a regionally optimized product for the entire North Sea is made available. It will enable further investigations of ocean processes, sea level projections, and studies on coastal adaptation measures. The North SEAL data are available at https://doi.org/10.17882/79673 (Müller et al., 2021).