The Cabbeling Instability in the High-Latitude Sea and Its Implications to the Iranian Sea

This study examines the role of physical water properties—temperature, salinity, and density—in ocean phenomena, focusing on water mass formation and instabilities like cabbeling and double diffusion. The Greenland Sea, with its complex mix of nine water types, serves as a key study area. Cabbeling, where mixing of water parcels creates denser water that sinks, and double diffusion, caused by differing temperature and salinity diffusion rates, significantly affect water column structure. Using thermodynamic analysis and data from the Greenland, Iceland, and Norwegian Seas, the research identifies fronts formed by Atlantic Water (AW) and Norwegian Atlantic Water (NWAW), characterizing their temperature, salinity, and spatial extent. Thermal expansion and saline contraction coefficients vary with depth and location, influencing cabbeling effects observed prominently between specific isopycnal layers. These effects promote sinking of dense water, impacting circulation and stability, as indicated by Brunt-Väisälä frequency and density ratio analyses. The study also explores implications for the Iranian Sea, where similar physical conditions exist in the Caspian Sea overflow and Persian Gulf Outflow. Cabbeling and double diffusion likely contribute to water sinking and nutrient transport there, affecting ecological habitats. The Greenland Sea serves as a model region due to the larger scale of these phenomena.