Atmospheric Turbulence Measurements at a Coastal Zone with and without Fog

Measurements of atmospheric turbulence at a site in Ferryland (Newfoundland) during the C-FOG (Coastal-Fog) field campaign in September–October 2018 are used to study meteorological parameters, turbulence statistics, internal boundary layers, and scaling laws for turbulent mixing in the coastal zone. We observe stable/unstable shallow internal boundary layers with a region of unstable/stable stratification above with onshore flow from a relatively warm/cold sea onto the cold/heated land during the night/day. This study compares surface fluxes and other turbulence statistics as well as different scaling laws with and without fog. While both complexity of the coastal landforms and foggy conditions nominally violate assumptions underlying Monin–Obukhov similarity theory (MOST), our observations show that the non-dimensional standard deviations of the velocity components and the dissipation rate of turbulence kinetic energy obey MOST reasonably well for all measurement levels, stability conditions, and wind directions for both fog and no fog cases. However, the data scatter for the normalized dissipation rate is somewhat greater compared with the normalized standard deviations of the wind components. The bias and relatively larger scatter of normalized standard deviations for scalars in near-neutral conditions is likely associated with the underlying inhomogeneous coastal surface. According to the C-FOG data, during a fog event the moisture flux data become irregular and the latent heat flux is often negative (downward). Our observations also demonstrate poor agreement between normalized standard deviations of specific humidity with MOST for foggy conditions; its statistical dependence on the MOST stability parameter is weak at best in fog.