Geostrophic departure and the functions A and B of Rossby-number similarity theory

Clarke, R. H.; Hess, Glenn

doi:10.1007/bf00240832

Cited by 71 publications

(62 citation statements)

References 11 publications

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“…The data seem to be consistent with the theoretical results but, in view of the estimated uncertainty in the individual estimates ofA, this conclusion can only be tentative, with data covering a greater range of M needed to reach a firm conclusion. The present data are in poor agreement with the dependence of A on baroclinicity found by Clarke and Hess (1974) for the Wangara data.…”

Section: The Rossby Similarity Functions a And Bsupporting

confidence: 50%

“…From these coefficients, both the magnitude and direction of the surface stress with respect to the geostrophic wind can be determined. A number of empirical estimates of A and B have been published, the majority based on various analyses of the Wangara data set (Clarke and Hess, 1974). More recently, Nicholls (1982) has obtained estimates ofA and B from Boundary-Layer Meteorology 39 (1987) 219-231. aircraft data collected during the 1978 JASIN experiment.…”

Section: Introductionmentioning

confidence: 99%

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Aircraft estimates of the geostrophic drag coefficient and the rossby similarity functions A and B over the sea

Grant

Whiteford

1987

Boundary-Layer Meteorol

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Estimates of the geostrophic drag coefficient and the Rossby similarity functions, A and B obtained from data collected by an instrumented aircraft over the sea are presented. The average value of the geostrophic drag coefficient is 0.027 and is independent of the geostrophic windspeed. The dependence of the similarity functions A and B on boundary-layer parameters is investigated. The function A is found to depend on baroclinicity parameters, while B depends on the parameter u t /fh (where u + is the surface friction velocity, f is the Coriolis parameter, and h is the boundary-layer depth). Using the geostrophic drag coefficient found here and the results of surface drag coefficient studies, a relationship between geostrophic windspeed and surface windspeed is obtained which shows good agreement with empirical data.

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Section: The Rossby Similarity Functions a And Bsupporting

confidence: 50%

Section: Introductionmentioning

confidence: 99%

Aircraft estimates of the geostrophic drag coefficient and the rossby similarity functions A and B over the sea

Grant

Whiteford

1987

Boundary-Layer Meteorol

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“…Although the functional form of B(*) has been studied by field observations and numerical models, there still remains a large ambiguity in the value of B(*). According to Clarke and Hess (1974), the value of B(*) is about 20 for a very stable case, about 4 for a neutral case and about 0.5 for a very unstable case. If their value is adopted, the depth of the surface layer is expected to be 5 times thinner for the stable case and 8 times deeper for the unstable case, than that for the neutral case.…”

Section: Discussionmentioning

confidence: 99%

On the Depth of the Surface Layer in the Turbulent Ekman Layer

Kinoshita¹,

Niino²

1990

Journal of the Meteorological Society of Japan

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“…Further attempts to derive the thermal winds were made by Clarke and Hess (1974) and Arya (1975a), based on surface temperature measurements. Threehourly surface temperature measurements from the same 14 Bureau of.Meteorology stations used for the geostrophic wind computations were employed for these computations.…”

Section: Description Of the Wangara Experimentsmentioning

confidence: 99%

“…Because of the variation in surface roughness over the experimental area, the spatially averaged momentum fluxes differ significantly from those determined from station 5 data alone. Clarke and Hess (1974) made an initial attempt to derive spatially averaged friction velocities by evaluating the friction velocities at station 4 and station 5 and taking a weighted average where the smooth site values were given three times the weight of the rough site values to account for the approximate distribution of roughness over the experimental area. These values have since been revised by Hicks (1980).…”

Section: Average Friction Velocitiesmentioning

confidence: 99%

The impact of the Wangara experiment

Hess

Hicks

Yamada

1981

Boundary-Layer Meteorol

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Our understanding of the structure and dynamics of the atmospheric boundary layer (ABL) is often limited by a lack of experimental data. The voluminous amount of high quality data obtained from the Wangara Experiment (Clarke et al., 1971) has contributed greatly to meeting a long-standing need, particularly for data describing the ABL in middle latitudes over land.In the surface layer the measurements provided the basis for determination of the stability dependence of the dimensionless gradients d,+, and dH arising out of Monin-Obukhov similarity theory (Hicks, 1976). In the outer layer where the choice of scaling parameters is not unique, the data have been used to determine the stability dependence of the similarity functions A, B, and C, and the most appropriate choices of scaling parameters (e.g., Yamada, 1976). In addition, the experimental data give determinations of some of the fundamental constants of turbulent flow in the ABL, such as the Von Kdrmin constant k = 0.40-0.41 (Hicks, 1969), and the neutral barotropic ABL similarity constants A,, = 1.1 and & = 4.3 (Clarke and Hess, 1974), where the subscript 0 indicates that the surface geostrophic wind was used as reference.Perhaps the greatest impact of the Wangara Experiment has been to provide a data bank which could be used to test numerical simulations of the ABL. This has been useful not only for the newly developed higher-order closure models, but also for one-layer integral models predicting the height of the mixed layer and the height of the nocturnal surface inversion layer.Lastly, the Wangara Experiment has pointed out some of the limitations and difficulties of obtaining accurate measurements of thermal winds, vertical velocity, acceleration terms, and representative spatially averaged fluxes. Microscale turbulence measurements outside the surface layer were not included in the Wangara Experiment and further experiments are needed to determine these statistics.

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Geostrophic departure and the functions A and B of Rossby-number similarity theory

Cited by 71 publications

References 11 publications

Aircraft estimates of the geostrophic drag coefficient and the rossby similarity functions A and B over the sea

Aircraft estimates of the geostrophic drag coefficient and the rossby similarity functions A and B over the sea

On the Depth of the Surface Layer in the Turbulent Ekman Layer

The impact of the Wangara experiment

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