Proceedings of the SeaSAR 2023 Workshop, 2-6 May 2023, Svalbard, Norway

Twenty years after the workshop on Coastal and Marine applications of SAR the SeaSAR2023 workshop returned to Svalbard from 2-6 May 2023 (https://seasar2023.esa.int). The workshop was sponsored by ESA and organized jointly with the Nansen Environmental and Remote Sensing Center (NERSC), the University Centre of Svalbard and Svalbard Integrated Arctic Earth Observing System (SIOS). SeaSAR2023 was arranged around keynote presentations and thematic discussions in plenary followed by thematic panel working group discussion and reporting. The themes included: Wave Retrievals Near Surface Wind Retrievals and Detection of Extremes Doppler Shift Retrievals Sea Ice Retrievals Sensor Synergy Methodology and Techniques Applications (Oil Spill, Ship Detection, etc) Future Missions Covering these 8 themes the main workshop objectives included: Review state-of-the-art in SAR-based geophysical parameter retrievals. Identification of knowledge gaps and deficiencies. Novel approaches for advancing scientific research and applications. Importance and needs for validation. The workshop brought together around 80 experts and researchers (see list of participants) from around the world to share the latest advancements and challenges in coastal and marine applications of satellite-based Synthetic Aperture Radar (SAR) technology. In addition, 76 individuals attended the on-line WebEx transmissions of the plenary and the eight breakout sessions throughout the week. The YouTube broadcasting of the first day plenary session was viewed 148 times, mostly in real-time. Thanks to more than 3 decades of continuity of SAR missions the coastal and marine SAR scientific research and applications community have significantly advanced the quantitative understanding of SAR imaging capabilities. This is highlighted in these Proceedings of the SeaSAR 2023 regarding upper ocean currents and mesoscale structures, wave spectra, internal waves, sea ice field, surface slicks, near surface wind fields, marine atmosphere boundary layer processes and extremes as well as advances in methodologies and techniques and applications for oil spills and ship detection. Moreover, the outlook beyond 2030 and towards 2040 clearly evidences the continuity and sustainable access to data from future approved satellite SAR missions. However, as pointed out during the workshop there are deficiencies and challenges regarding design and implementation of a more comprehensive satellite SAR-based calibration-validation approach, jointly with systematic use of sensor synergy across the broad range of complementary satellite radar altimeters, scatterometry, interferometry, and highresolution optical radiometer and spectrometer. This will require dedicated international collaboration with involvement of the space agencies, in particular to enable multi-frequency and multi-look direction SAR-based observations with shorter imaging interval. Combined with continuous free and open available SAR data this will strengthen the generation of training datasets for machine learning development.