High-resolution airborne infrared measurements of ocean skin temperature

Airborne measurements of ocean skin temperature T_s are presented from the Coupled Boundary Layers, Air-Sea Transfer in Low Winds (CBLAST-Low) Pilot Experiment in August 2001 off Martha´s Vineyard, MA. We used an infrared (IR) camera with a spatial resolution of 1 m or less and temperature resolution of roughly 0.02°C. Using subframe sampling of the IR imagery, we achieve lower noise and higher spatial resolution than reported by previous investigators using IR radiometers. Fine-scale maps of T_s exhibit horizontal variability over spatial scales ranging from O(10 km) down to O(1 m) that are related to atmospheric and subsurface phenomena under low to moderate wind conditions. Based on supporting measurements of wind and waves, we identify coherent ramp-like structures in T_s with stratification breakdown and meandering streaky features with internal waves. Regional maps of T_s show the standard deviation for the region is ±1.04°C, while the meridional and zonal variability is 0.23°C · km^-1 and 0.27°C · km^-1, respectively. This temperature variability results in meridional and zonal scalar heat flux variability of 7.0 W · m^-2 · km^-1 and 7.6 W · m^-2 · km^-1, respectively. Our results demonstrate the potential for airborne IR imagery accompanied by high-quality ocean data to identify T_s features produced by subsurface circulation.