The Dynamic Influence of Air-Sea Temperature Gradient on Near-Surface Turbulent Eddy Scales within the Marine Atmospheric Boundary Layer.

In the marine atmospheric boundary layer (MABL), the difference in temperature between the air just above the sea surface and the water at the sea surface, △T is a driving parameter for characterizing the vertical variability of the wind velocity field, and, indirectly, the atmospheric stability. For this study, wind velocity data collected at Galveston Island State Park, Texas, with a scanning wind LiDAR are coupled with wind/sea data collected from a buoy station deployed in the proximity of this coastal site at a distance of 32 miles from the shore to investigate the variability of the MABL velocity field with different atmospheric/wave conditions. Preliminary findings indicate the prevalence of old waves during onshore conditions and young waves during offshore conditions. Furthermore, onshore wind conditions are typically associated with a positive △T, namely the air temperature is larger than the water temperature. Conversely, the occurrence of negative △T is typically associated with offshore winds. The dimensionless velocity gradient derived from LiDAR measurements shows a correlation with △T, thus with the Bulk Richardson number. Finally, it is observed that positive △T, which can be associated with stable atmospheric conditions, leads to a significant increase in wind shear.