The North Sea is vulnerable to effects of climate change with significant societal impact on the coastal population. Satellite-based observations of Essential Climate Variables (ECVs) are cost-effective with complete spatial coverage within days not to be accomplished with hydrographic surveys using ships and monitoring buoys. However, calibration and validation of remote-sensed satellite data are challenging due to mismatch in the depths of measurements between satellite signals and in-situ data, and interferences from land-based contamination. For this purpose, we collected complementary surface data of ECVs during cruise HE598, HE609, HE614, HE626 and HE626/2. We will match our sea surface data with satellite observations of the two key ECVs sea-surface temperature and salinity. Based on the acquired data sets, new digital technology using explainable artificial intelligence (XAI) algorithms will be developed in the framework of the project NorthSat-X funded by the Ministry of Science and Culture (MWK) of the Lower Saxony State.

Two days of the last cruise were used to test the deployment and operation of the new research catamaran GLAUCUS ATLANTICUS, and to test a first simultaneous operation with the catamaran HALOBATES. Full operation of both catamarans is planned for project “Biogeochemical processes and Air-sea interaction in the Sea-Surface microlayer” (BASS; DFG research unit FOR5267) and FreshOcean (DFG).

The aim of the cruises was to investigate the surface variability of the essential climate variables sea surface temperature and salinity in the German Bight. Due to the large river discharges (e.g. Elbe, Weser and Ems) and precipitation, the German Bight fulfills the conditions for the existence of horizontal and vertical temperature and salinity gradients. In this context, we also investigate the distribution of marine pollutants, e.g. polyaromatic hydrocarbons and microplastics.