Sea Surface Temperature (SST) modifies the turbulent mixing, drag, and pressure gradients within the marine atmospheric boundary layer that accelerate near‐surface flow from cool to warm SST, and decelerates the flow from warm to cool SST. This phenomenon is well documented on scales of 100 − 1,000km (the oceanic mesoscale), however, the nature of this air‐sea coupling at scales on the order of 1 − 10km (the submesoscale) remains unknown. The Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) can be used to study submesoscale phenomena because the high resolution infrared and near infrared images can used to estimate both SST and wind speed. Observations of dramatic temperature and wind gradients along the Gulf Stream landward edge are used to examine the surface wind response to submesoscale fronts in SST. Our analysis indicates that SST‐induced wind speed perturbations are observed at the scales of order 1 − 10km, significantly smaller than previously suggested.

Air‐sea gas fluxes are generally defined in terms of the air/water concentration difference of the gas and the gas transfer velocity,k_L. Because it is difficult to measure k_Lin the ocean, it is often parameterized using more easily measured physical properties. Surface divergence theory suggests that infrared (IR) images of the water surface, which contain information concerning the movement of water very near the air‐water interface, might be used to estimatek_L. Therefore, a series of experiments testing whether IR imagery could provide a convenient means for estimating the surface divergence applicable to air‐sea exchange were conducted in a synthetic jet array tank embedded in a wind tunnel. Gas transfer velocities were measured as a function of wind stress and mechanically generated turbulence; laser‐induced fluorescence was used to measure the concentration of carbon dioxide in the top 300 μm of the water surface; IR imagery was used to measure the spatial and temporal distribution of the aqueous skin temperature; and particle image velocimetry was used to measure turbulence at a depth of 1 cm below the air‐water interface. It is shown that an estimate of the surface divergence for both wind‐shear driven turbulence and mechanically generated turbulence can be derived from the surface skin temperature. The estimates derived from the IR images are compared to velocity field divergences measured by the PIV and to independent estimates of the divergence made using the laser‐induced fluorescence data. Divergence is shown to scale withk_Lvalues measured using gaseous tracers as predicted by conceptual models for both wind‐driven and mechanically generated turbulence.

Laboratory experiments were conducted to measure the heat flux from seafoam continuously generated in natural seawater. Using a control volume technique, heat flux was calculated from foam and foam-free surfaces as a function of ambient humidity (ranged from 40% to 78%), air–water temperature difference (ranged from −9 °C to 0 °C), and wind speed (variable up to 3 m s⁻¹). Water-surface skin temperature was imaged with a calibrated thermal infrared camera, and near-surface temperature profiles in the air, water, and foam were recorded. Net heat flux from foam surfaces increased with increasing wind speed and was shown to be up to four times greater than a foam-free surface. The fraction of the total heat flux due to the latent heat flux was observed for foam to be 0.75, with this value being relatively constant with wind speed. In contrast, for a foam-free surface the fraction of the total heat flux due to the latent heat flux decreased at higher wind speeds. Temperature profiles through foam are linear and have larger gradients, which increased with wind speed, while foam free surfaces show the expected logarithmic profile and show no variation with temperature. The radiometric surface temperatures show that foam is cooler and more variable than a foam-free surface, and bubble-resolving thermal images show that radiometrically transparent bubble caps and burst bubbles reveal warm foam below the cool surface layer, contributing to the enhanced variability.

The long-term goal is to understand the mechanisms that produce spatial variability over a wide range of scales in ocean surface skin temperature under low wind conditions.

The importance of accurate measurements of ocean surface skin temperature T _skin is increasingly recognized for a wide range of air–sea interaction research. However, T _skin measurements currently are made using complex infrared radiometer systems that have been limited to ship deployments. Major measurement challenges are in situ calibration, a separate sky measurement to correct for reflected downwelling radiance, and emissivity uncertainty. The Infrared Instrument for Sea Surface Temperature (IRISS) is a simplified design that uses a one-point in situ calibration and separate sensors to measure the sea and sky radiance. The standard wavelength band (9.6–11.5 μ m) and a so-called optimal band (7.5–7.85 μ m) were evaluated by comparison to the Remote Ocean Surface Radiometer (ROSR) during an extensive field deployment. Both versions were found to have accuracy comparable to ROSR and thus meet the design goal of ±0.10°C. The sky radiance spectrum was modeled with moderate resolution atmospheric transmission (MODTRAN) 6 using radiosonde profiles of air temperature and water vapor. The results show that for the optimal band version, the modeled sky radiance can be used in place of the measured sky radiance without significant effect on the accuracy. The innovations of a one-point calibration and no sky measurement significantly increase the practicality and accessibility of T _skin measurements not only from ships but also from uncrewed surface vehicles and buoys.