Coastal Zone Wind-Wave Dynamics in the Marine Atmospheric Boundary Layer

The wind-wave coupling processes in the Marine Atmospheric Boundary Layer (MABL) are of prime importance in understanding production and transport of marine aerosol, which depend on several factors including wind shear, wave characteristics and atmospheric stability. The coastal zone of the MABL particularly undergoes complex processes of wave breaking that significantly differ from the less violent conditions over the open ocean. Using ground based simultaneous and co-located measurements of wind speed and aerosol backscatter from a pulsed Doppler wind LiDAR, it is possible to characterize the spatio-temporal distribution of marine aerosol under different wind/wave/atmospheric conditions. High-resolution fixed scans enable us to estimate the turbulent boundary flow parameters, such as the friction velocity and the total aerodynamic roughness length in the coastal zone.

We compare measurements collected at the coastal zone of the Galveston Bay, TX with the open ocean model described in Andreas et al. (JAS 2012). Variations of orders of magnitude in the aerodynamic roughness are estimated which correspond to deviations from expected friction velocity in the open ocean model. We also investigate the correlation of the wave parameters with the aerosol backscatter. A noteworthy trend between the 10-m reference wind speed, aerosol backscatter and wave steepness is observed. These findings provide a strong evidence of aerosol dominated wind-wave processes in the coastal region of the MABL.