The sea surface microlayer (SML; <1 mm)) and near-surface layers (NSL; < 1.2 meters) play a critical role in physical, chemical, and biological processes that regulate air–sea exchange. These layers respond rapidly to fluctuations in meteorological forcing. Episodic events, such as rain, storms, slicks, and fronts, rapidly disrupt the SML and NSL, creating sharp changes in structure and function that fuel short-term variability. In contrast, persistent anomalies, including seasonal stratification, shape more stable biogeochemical patterns in air–sea exchange over extended timescales. This session invites contributions on recent advances in understanding the physicochemical and biological characteristics of the SML and NSL. By integrating perspectives on gradients, episodic forcing, and biogeochemical reactivity, we aim to highlight how physical, chemical, and biological processes are tightly interconnected, and how the functioning of the SML is regulated by its dynamic coupling with the underlying water (ULW) column across different spatial and temporal scales.
We particularly welcome studies that address the SML’s role in modulating exchanges of heat, momentum, freshwater, gases, particles, and biota, as well as its coupling and decoupling with the ULW. Topics of interest include variability in temperature, salinity, organic and inorganic matter, surfactants, nutrients, microbial communities, and gas fluxes, as well as how these multiple interacting drivers influence solubility and turbulence, and affect air–sea CO₂ fluxes. We strongly encourage contributions from diverse approaches, including field observations, laboratory experiments, autonomous platforms, and modeling, to advance a mechanistic understanding of the SML and NSL as dynamic interfaces shaping air–sea exchange.