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The estimation and evapotranspiration of wheat field - An improved energy-aerodynamic resistance model
Agropédologie ; Bilan énergétique ; Chine ; Cycle de l'eau ; Céréale ; Evapotranspiration ; Géographie de l'Asie ; Modèle ; Résistance aérodynamique
Results and discussion of the energy balance-aerodynamic resistance model for estimating the evapotranspiration of crops.

Aerodynamic roughness of gravel surfaces

Aerodynamic roughness of gravel surfaces
The AA. report detailed results with respect to the aerodynamic roughness of different gravel surfaces from wind tunnel experiments. With the philosophy that aerodynamic roughness of gravel surfaces is a function of gravel size, spacing and the near
-surface airflow characteristics, the specific purposes are to define the change of aerodynamic roughness length with wind speed, gravel size and coverage and roughness Reynolds number; and establish prediction models for aerodynamic roughness length

Une expression simplifiée de la résistance aérodynamique d'un couvert végétal. (Application à la mesure des flux de masse et d'énergie). (A simplified expression for the aerodynamic resistance over uniform surfaces)
Chaleur sensible ; Couverture végétale ; Cycle de l'eau ; Ecologie quantitative ; Evaporation ; Evapotranspiration ; Flux de masse ; Géographie physique ; Interface végétation-atmosphère ; Micrométéorologie ; Méthodologie ; Météorologie ; Résistance
Après avoir rappelé comment la résistance aérodynamique d'un couvert végéral varie en fonction de la hauteur du couvert, de la vitesse du vent et de la stabilité des basses couches atmosphériques, on montre la manière d'utiliser une expression
simple de cette résistance, ne faisant intervenir que la hauteur du couvert végétal, dans certaines conditions climatiques bien spécifiques. Application à la détermination du flux de vapeur d'eau et de chaleur sensible au-dessus de deux couverts végétaux

Aerodynamic entrainment thresholds and dislodgement rates on impervious and permeable beds
Using a range of grain sizes and flow conditions, the series of laboratory experiments reported here compares directly the aerodynamic entrainment of loose grains overlying fixed permeable sediment beds with that occurring over fixed impervious beds.

Width, height and slope relationships and aerodynamic maintenance of barchans
one-tenth of the width of the dune. The AA. attempt to assess the factors (particularly slope and aerodynamics) that act to produce and maintain the barchan dune shape.

Aerodynamical properties of an air layer affected by vegetation
of the aerodynamic properties, varying with wind speed is based on measurements carried out at the heat and water balance observation field in the Environmental Research Center between 1978 and 1980. The validity of theoretical relationships between the canopy

Relations between aerodynamic and surface roughness in a hyper-arid cold desert : McMurdo dry valleys, Antarctica

Formation of ventifacts in Antarctica is mainly a result of erosion by aerodynamic and vorticity processes, as well as by grain impact. Suspended particles of dust, silt and ice crystals are the agents of erosion as they are transported
in interfacial flow lines of the impacting airstream. Although salt weathering may play a part in the formation of concave basal surfaces and other basel features, perhaps by initiating or enhancing wind-eroded features, the predominant force is aerodynamic.

Causes of the fetch effect in wind erosion

would dislodge one or more particles upon impact with the surface; 2) the aerodynamic feedback effect in which the aerodynamic roughness height is increased by saltation of particles; 3) the soil resistance mechanism, which is largely an expression

are the zero plane displacement, d, and aerodynamic roughness parameter, Z0. Results and discussion.

In this paper, the micrometeorological characteristics of rubber tree stands, heat balance, radiative and aerodynamic properties are analyzed with data for three years (April 1986 to March 1989).

This paper describes the existence and maintenance (a day at least) of some unusual crescentic dunes on a frozen beach at Schiermonnikoog. These crescentic dunes displayed a markedly aerodynamic shape, and had a plan view similar to that of barchans

) processes play a role in dust ripple dynamics : an aerodynamic process and an impact process, of which the first causes an upwind and the second a downwind migration of the ripples.

On the South African south coast, transgressive dunefields are the dominant dune complex. The aerodynamics and sand transport of one small (1 m high) transverse dune were examined on a tabular dunefield. The point where sand movement is initiated

characteristics are calculated including the albedo, radiation temperature, emissivity, aerodynamic and canopy resistances. The results are used to test parameterizations to calculate several heat fluxes, including the fraction of energy used in evaporation.

different types of pebbles. Aerodynamic flow separation and diverging and converging airflow play an important role in the process of dust deposition on stone-covered surfaces.

Energy exchange at a glacier surface: an alternative to aerodynamic methods of measurement

surface groups with similar emission behaviour and aerodynamic characteristics were identified: (1) sand surfaces, (2) rough stone surfaces and (3) flat crusted surfaces. These results are comparable with field studies of natural erosion events and similar

to an influence of climatic elements and weather types, but coarse particles to a lesser extent than PM 2.5 (particles with an aerodynamic diameter

This paper presents field evidence of dust entrainment by direct aerodynamic suspension in the absence of significant saltation. They propose to examine whether saltation was occurring by utilizing actual friction velocity and roughness height

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