Airborne Sea Surface Salinity Monitoring Along Greenland with a low-carbon platform: Requirements Assessment and Review of Existing Instrument

The rapid warming of the Arctic could drive some critical parts of the Earth system towards tipping points. For tipping elements involving ocean circulation (eg. Atlantic Meridional Overturning Circulation – AMOC, or sub-polar gyre - SPG), remote sensing of sea surface salinity (SSS), temperature (SST), height (SSH) or current (Total Surface Current Vector - TSCV) can detect fingerprints of the proximity of tipping points.While spaceborne satellite sensors provide large-scale SSS coverage, their spatial (> 50 km) resolution is insufficient to capture coastal and (sub-) mesoscale processes, especially in dynamic regions like Greenland’s continental shelves with fast-changing sea ice. In situ platforms, though precise, lack the spatial and temporal coverage required to capture spatial structures, and monitor rapid changes and extreme events.This contribution presents a requirement assessment for airborne SSS measurements along Greenland, focusing on the unique challenges posed by the encountered environmental conditions (low SST, presence of sea ice, …), and the need for low-carbon, scalable observing platforms. We evaluate the scientific and operational requirements for SSS retrievals, including spatial resolution (100 m–10 km), revisit frequency, and accuracy (0.1-1 pss), and discuss the trade-offs between platform endurance, payload capacity, and environmental impact.We then review suitable instrumentation for airborne SSS mapping, with an emphasis on technologies compatible with low-carbon platforms such as drones, high-altitude pseudo-satellites (HAPS), and airships.The potential for multi-sensor fusion—combining SSS with sea surface temperature, currents, and wind measurements—is also explored, as is the integration of airborne data with satellite and in situ networks.