The influence of boundary layer pumping on an externally-forced
synoptic-scale flow is examined. The results follow earlier theories of
stratified incompressible Boussinesq flow. These theories state that
the spin-down time scale and the penetration depth of the influence of
boundary layer pumping are inversely proportional to the stratification
and directly...
Four buoyant plumes were produced within a laboratory convectively
mixed layer from a source height of about z[subscript s] = 0.15 h,
where h is the height of the convectively mixed layer. The
projected images of these plumes in the X-Z plane were analyzed
using a densitometer (photomultiplier tube) to...
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...
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....
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...
The influence of irregular terrain on the evolution of the daytime
planetary boundary layer (PBL) and meso-β scale dry circulations is
studied using two three-dimensional hydrostatic σ-coordinate models
with different approaches for the PBL parameterizations; the 4-layer
model uses the mixed-layer (bulk-layer) approach, while the 7-layer
model adopts the eddy-diffusivity...
A baroclinic, convective mixed-layer was modeled, using
water, in a laboratory convection tank identical to that
used in the free convection study of Deardorff and Willis
(1985). Baroclinicity and mean-flow shearing were achieved
by tilting the tank by an angle of 1O⁰. The resulting
mechanical-production rate of turbulence kinetic energy...
Precision irrigation has made spatially explicit water management a reality. However, detailed knowledge about the spatially variable evapotranspiration is often unavailable. One example location where we can begin to understand the impact of spatial variability on evapotranspiration is at the field edge, which contains a sharp discontinuity in surface conditions....
A time dependent model of the shallow, tropical convective boundary layer is
developed and tested. To simplify the treatment of thermodynamic processes and
return to first principles of physics, conserved quantities of entropy and total
water density are used as primary model variables. In addition, a new shallow
cumulus parameterization...