Sea Surface Temperature at 1 km spatial Resolution between 1990 and 2022 for the Baltic and North Sea: Insights from the new TIMELINE AVHRR SST Product

Kurzfassung

Coastal areas are among the most economically and ecologically productive areas in the world but are threatened by rising oceanic temperatures. Sea Surface Temperature (SST) is an essential variable to monitor and understand oceanic warming trends, especially in coastal areas. Remote sensing is one means of measuring SST over long time scales. Current SST products, however, have fairly coarse spatial resolution, limiting the application of remotely-sensed SST at finer scales in coastal zones. We present the novel TIMELINE 1km SST product, derived from the Advanced Very-High-Resolution Radiometer instrument, that spans over 30 years for Europe. Additionally, this study analyzes this product in the Northern and Baltic Seas. The analysis of monthly anomaly trends found high positive SST trends in this study area, exceeding the global average SST warming. Warmer and colder periods, such as the 2006 heatwave, could also be identified and aligned with previous research. Seasonal variations reveal peak warming during spring, early summer, and early autumn, suggesting a potential seasonal shift. The spatial analysis of the monthly anomaly trends revealed significantly higher trends in near-coastal areas. The TIMELINE monthly anomaly time series were also compared to monthly anomalies derived from the ESA Climate Change Initiative Level 4 SST anomaly product. The comparison showed an overall strong accordance of the two products (R = 0.77) for the North and Baltic Sea. This study highlights the potential of the TIMELINE SST product for mapping long-term SST trends in areas with high spatial SST variability, such as coastal regions, as well as for preparing for future sea surface temperature extremes.