Fine-scale water mass transformations are critical to understanding ocean dynamics, climate variability, and biogeochemical cycles. Despite their importance, observing the processes governing these transformations and associated fluxes remains challenging due to their ephemeral nature and small spatial-temporal scales. This session highlights recent advances in capturing these elusive processes—including mesoscale and submesoscale dynamics, internal wave interactions, turbulent mixing, and boundary layer exchanges—using a variety of novel observational approaches. These include autonomous platforms, high-resolution sensors, tracer releases, and remote sensing.

Water mass transformation (WMT) is often studied in polar regions, where it underpins large-scale overturning circulation. However, there is growing recognition of the importance of fine-scale processes in marginal seas, western boundary currents, and other dynamic regions that also drive water mass modification. We especially welcome contributions linking these processes to quantitative flux estimates of heat, salt, carbon, nutrients, and emerging contaminants such as microplastics.

This session aims to bridge observational, theoretical, and modeling approaches within the broader WMT framework. We encourage submissions across disciplines and invite presentations of early-stage or exploratory methods to stimulate discussion. Our goal is to foster interdisciplinary dialogue, identify gaps in capabilities, and chart future directions for understanding fine-scale processes as fundamental components of the climate system.

• Physical Oceanography: Mesoscale and Smaller -