Spatial variations of surface stress over the coastal shoaling zone are studied offshore of Duck, North Carolina, by the LongEZ research aircraft, equipped to measure both atmospheric turbulence and oceanic waves. We find that the spatial variation of the friction velocity with offshore distance is much larger with offshore flow...
Lake-induced atmospheric circulations over three lakes ranging from 3 to 10 km width are analyzed using data from three aircraft during the 1994 Boreal Ecosystem-Atmosphere Study (BOREAS). A well-defined divergent lake breeze circulation is observed over all three lakes during the day. Under light wind conditions, the lake breeze is...
Toward the goal of predicting area-averaged evapotranspiration, the evaporative fraction is modelled in terms of surface radiation temperature, air temperature, solar zenith angle, Normalized Difference of the Vegetation Index and albedo. Previous relationships break down when applied simultaneously to a variety of surfaces. The zenith angle is required to account...
Aircraft data collected at approximately 15 m above the sea surface in the coastal zone are analyzed to examine the spatial distribution of surface stress. Advection of stronger turbulence from land dominates the near-surface turbulence for the first few kilometers offshore. With offshore flow of warm air over cold water,...
This study examines the spatial variability of ozone fluxes over flat heterogeneous terrain consisting of a patchwork of irrigated and nonirrigated surfaces. Fluxes of ozone and other quantities are computed from eight sequential flight legs of the Canadian Twin Otter research aircraft over the same track at 33 m above...
The value of the effective exchange coefficient for area-averaged fluxes can depend significantly on the averaging scale. This dependence implies that the exchange coefficient in numerical models should depend on grid size. The main goal of this study is the assessment of the importance of such scale-dependence. When the large-scale...
The light-wind, clear-sky, very stable boundary layer (vSBL) is characterized by large values of bulk
Richardson number. The light winds produce weak shear, turbulence, and mixing, and resulting strong
temperature gradients near the surface. Here five nights with weak-wind, very stable boundary layers during
the Cooperative Atmosphere–Surface Exchange Study (CASES-99)...
The Office of Naval Research's Coupled Boundary Layers and Air–Sea Transfer (CBLAST) program is being conducted to investigate the processes that couple the marine boundary layers and govern the exchange of heat, mass, and momentum across the air–sea interface. CBLAST-LOW was designed to investigate these processes at the low-wind extreme...
An investigation of nocturnal intermittent turbulence during the Cooperative Atmosphere Surface Exchange Study in 1999 (CASES-99) revealed three turbulence regimes at each observation height: 1) regime 1, a weak turbulence regime when the wind speed is less than a threshold value; 2) regime 2, a strong turbulence regime when the...
Relationships among the horizontal pressure gradient, the Coriolis force, and the vertical momentum transport by turbulent fluxes are investigated using data collected from the 1999 Cooperative Atmosphere-Surface Exchange Study (CASES-99). Wind toward higher pressure (WTHP) adjacent to the ground occurred about 50% of the time. For wind speed at 5...