Satellite Observations of SST-Induced Wind Speed Perturbation at the Oceanic Submesoscale

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 decelerate the flow from warm to cool SST. This phenomenon is well documented on scales of 100-1,000 km (the oceanic mesoscale); however, the nature of this air-sea coupling at scales on the order of 1-10 km (the submesoscale) remains unknown. The Advanced Spaceborne Thermal Emission and Reflection Radiometer 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 1-10 km, significantly smaller than previously suggested. Plain Language Summary Seafarers have long known that winds speed up over warm water. The reason for this was not fully understood until the mid-1990 s when satellite observations of sea surface temperature and winds revealed that this phenomenon can be observed in regions where large gradients in sea surface temperature occur. The basic mechanism is quite simple; warm water allows the movement of winds higher up in the atmosphere to be transferred down near the ocean's surface. This is accentuated by a difference in atmospheric pressure over warm and cold water driving a wind from high to low pressure. Using a satellite sensor built to image land, we developed methods to estimate both the sea surface temperature and wind speed at an unprecedented resolution of 100 m, revealing that this phenomenon occurs at spatial scales as small as 1km and over the course of minutes. These observations provide evidence that sea surface temperature induced wind anomalies not only occur at incredibly small scales, in terms of the vastness of the World Ocean, but also that this phenomenon should be included in global atmosphere/ocean simulations if we are to correctly forecast winds over the ocean.