Boundary-layer data from several different geographical locations are analyzed to document the behavior of boundary-layer shear above the surface. The influence of diurnal variation of stability is emphasized. The applicability of the power law for use in shear estimates is examined.
This study examines the inadequacies of formulations for surface fluxes for use in numerical models of atmospheric flow. The difficulty is that numerical models imply spatial averaging over each grid area. Existing formulations am based on the relationship between local fluxes and local gradients and appear to describe the relationship...
Radiosonde data from the National Hail Research Experiment and the Wangara experiment are examined to study vertical gradients of moisture in heated boundary layers which are well-mixed in virtual potential temperature. The frequent occurrence of a significant decrease of moisture with height in the mixed layer over the high plains...
Lagrangian equations for momentum and buoyancy are developed for idealized turbulent fluid elements. The resulting formulation of transport can he viewed as a generalization of mixing length and parcel theories of mixing for application to gridded Eulerian models. This formulation of transport recognizes the mean gradients on the scale of...
The structure of turbulence in a strongly stratified nocturnal boundary layer is studied using fast-response aircraft data collected under clear sky conditions with weak ambient flow. The principal source of turbulence is shear generation near the top of the surface inversion layer. This shear is induced by the development of...
An analytical two-layer approximation of atmospheric flow is developed to study boundary-layer production of vertical motion. The model consists of a boundary layer topped by a free-flow layer. Both layers am time-dependent and possess different values of stratification. The boundary-layer equations are layer-integrated over a fixed depth and surface stress...
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 theories in that the spin-down time scale and the penetration depth of the influence of boundary layer pumping are inversely proportional to the stratification and proportional...
Condensed water content (CWC) measured using a counterflow virtual impactor (CVI) with a Lyman-α hygrometer downstream is compared with that measured by other airborne instruments (a hot-wire probe, a PMS FSSP, and a PMS 2D-C). Results indicate that the CVI system provides a reliable measurement of CWC in both liquid-...
Due to distortion of airflow streamlines, flow velocities and droplet size distributions measured around a moving aircraft can differ from freestream conditions. This can complicate measurements made from aircraft platforms. Potential flow calculations were used to predict airflow characteristics and the spatial distribution of different-sized droplets around the Lockheed Electra...
In this article the authors examine the kinematics and dynamics of the seasonal cycle in the western Indian Ocean in an eddy-permitting global simulation [Parallel Ocean Circulation Model, model run 4C (POCM-4C)]. Seasonal changes of the transport of the Agulhas Current are linked to the large-scale circulation in the tropical...