Atmospheric boundary layers become stably stratified at night over land when the surface becomes colder than the air layer above. In stable nocturnal boundary layers (SNBL), turbulence becomes weak and intermittent, terrain-induced phenomena such as drainage currents or gravity-waves emerge and the surface heterogeneity is enhanced. Because of their complexity...
Sudden changes occur where the mean values associated with two adjacent non-overlapping
windows of data are anomalously different, and the transition between the
window means occurs over a scale that is small relative to the scale of the windows.
Positions of sudden changes can be economically retrieved. The sudden change...
Globally intermittent turbulence is characterized by sudden switching from significant turbulence to weak turbulence and back on time scales ranging from seconds to tens of minutes as opposed to microscale intermittency, which is due to organization of small scale gradients by individual eddies on scales as small as the Kolmogorov...
This study concentrates on analysis of LongEZ aircraft data taken offshore of the Atlantic Coast of the United States. Due to the land structure of the region, it was possible to isolate the effect of narrow land on air as it flows offshore. The narrow land (Outer Banks) separates inland...
A two-scale approach for the turbulent mixing of momentum in an unstable stratified boundary layer is proposed in an attempt to eliminate existing inconsistencies between parameterized mixing of heat and momentum. The parameterization of the large eddy stress is suitable for simple boundary layer models where computational efficiency is important....
The very stable boundary layer is a region of the atmosphere typified by large
vertical gradients of temperature and momentum. Analysis of very stable atmospheric
flows is complicated by the presence of nonlinear interactions among gravity waves, shear-driven
overturning circulations, two-dimensional vortical modes and intermittent turbulence
in various stages of...
The use of efficient basis functions to model and represent flows with
internal sharp velocity gradients, such as shocks or eddy microfronts, are
investigated. This is achieved by analysing artificial data, observed atmospheric
turbulence data and by the use of a Burgers' equation based spectral
model. The concept of an...
An eigenvector analysis of the velocity-temperature correlation
matrix is applied to clear-air turbulence measured by aircraft in the
Bora. The eigenvectors are identified with the main eddies of the
turbulence. This study attempts to infer the three-dimensional
structure of these eddies. The results are compared with turbulent
structures in the...