Abstract
Multi-level turbulent wind data from the Risø Air-Sea Experiments (RASEX) were used to examine the structure of large-scale motions in the marine atmospheric surface layer. The quadrant technique was used to identify flux events (ejections/sweeps). Ejections, which appear to occur in groups, are seen to occur first at the upper level, moving successively to lower levels with small time delays. A strong correlation between events at different heights suggests that they may all be part of a single large structure. Cross-correlation between velocity signals was used to estimate orientation of the structure using Taylor's hypothesis. The inclination of this structure is shallow (≃ 15°) near the surface and increases with height. Spatial representations of the fluctuating wind vectors show a structure that is strikingly similar to conceptual models of transverse vortices and shear layers seen in laboratory flows and direct numerical simulation (DNS) of low Reynolds number flows. Spatial visualization of velocity fluctuations during other time periods and conditions clearly shows the existence of shear layers, transverse vortices, plumes, and downdrafts of various sizes and strengths. A quantitative analysis shows an increase in the frequency of shear related events with increasing wind speed.
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Barthelmie, R. J., Courtney, M. S., Høstrup, J., and Sanderhoff, P.: 1994, The Vindeby Project: A Description, Risø National Laboratory, Roskilde, Denmark, Rep. R-741(EN), 40 pp.
Bogard, D. G. and Tiederman, W.G.: 1986, 'Burst Detection with Single-Point Velocity Measurements', J. Fluid Mech. 162, 389–413.
Boppe, R. S. and Neu, W. L.: 1995, 'Quasi-Coherent Structures in the Marine Atmospheric Surface Layer', J. Geophys. Res. 100(C10), 20635–20648.
Chen, C. H. P. and Blackwelder, R. F.: 1978, 'Large-scale Motion in a Turbulent Boundary Layer: A Study Using Temperature Contamination', J. Fluid Mech. 89, 1–31.
Collineau, S. and Brunet, Y.: 1993, 'Detection of Turbulent Coherent Motions in a Forest Canopy Part 2: Time-Scales and Conditional Averages', Boundary-Layer Meterorol. 66, 49–73.
Davidson, D. S.: 1974, 'The Translation Velocity of Convective Plumes', Quart. J. Roy. Meteorol. Soc. 100, 572–592.
Farge, M.: 1992, 'Wavelet Transforms and their Application to Turbulence', Annu. Rev. Fluid Mech. 24, 395–457.
Gao, W., Shaw, R. H., and Paw U, K. T.: 1992, 'Conditional Analysis of Temperature and Humidity Microfronts and Ejection/Sweep Motions within and above a Deciduous Forest', Boundary-Layer Meteorol. 59, 35–57.
Gerz, T., Howell, J., and Mahrt, L.: 1994, 'Vortex Structures and Microfronts', Phys. Fluids 6, 1242–1251.
Högström, U. and Bergström, H.: 1996, 'Organized Turbulence Structures in the Near-Neutral Atmospheric Surface Layer', J. Atmos. Sci. 53, 2452–2464.
Hussain, A. K.M. F.: 1981, 'Coherent Structures and Studies of Perturbed and Unperturbed Jets', The Role of Coherent Structures in Modeling Turbulence and Mixing, Springer-Verlag, New York, pp. 252–291.
Hussain, A. K. M. F.: 1986, 'Coherent Structures and Turbulence', J. Fluid Mech. 173, 303–356.
Kaimal, J. C.: 1974, 'Translation Speed of Convective Plumes in the Atmospheric Surface Layer', Quart. J. Roy. Meteorol. Soc. 100, 46–52.
Kaimal, J. C. and Businger, J. A.: 1970, 'Case Studies of Convective Plumes and a Dust Devil', J. Appl. Meteorol. 9, 612–620.
Kaimal, J. C. and Finnigan, J. J.: 1994, Atmospheric Boundary Layer Flows: Their Structure and Measurement, Oxford University Press, New York, 289 pp.
Katul, G. G., Albertson, J., Parlange, M., and Stricker, H.: 1994, 'Conditional Sampling, Bursting, and the Intermittent Structure of Sensible Heat Flux', J. Geophys. Res. 99(D11), 22869–22876.
Lu, S. S. and Willmarth, W. W.: 1973, 'Measurement of Structure of the Reynolds Stress in a Turbulent Boundary Layer', J. Fluid Mech. 60, 481–511.
Lykossov, V. N. and Wamser, C.: 1995, 'Turbulence Intermittency in the Atmospheric Surface Layer over Snow-Covered Sites', Boundary-Layer Meteorol. 72, 393–409.
Mahrt, L.: 1989, 'Intermittency of Atmospheric Turbulence', J. Atmos. Sci. 46, 79–95.
Mahrt, L. and Gibson, W.: 1992, 'Flux Decomposition into Coherent Structures', Boundary-Layer Meteorol. 60, 143–168.
Mahrt, L. and Howell, J. F.: 1994, 'The Influence of Coherent Structures and Microfronts on Scaling Laws Using Global and Local Transforms', J. Fluid Mech. 260, 247–270.
Perry, A. E. and Li, J. D.: 1990, 'Experimental Evidence for the Attached-Eddy Hypothesis in Zero Pressure Gradient Turbulent Boundary Layers', J. Fluid Mech. 218, 405–438.
Phong-anant, D., Antonia, R. A., Chambers, A. J., and Rajagopalan, S.: 1980, 'Features of the Organized Motion in the Atmospheric Surface Layer', J. Geophys. Res. 85(C1), 424–432.
Rempfer, D. and Fasel, H. F.: 1994, 'Evolution of Three-Dimensional Coherent Structures in a Flat-Plate Boundary Layer', J. Fluid Mech. 260, 351–375.
Robinson, S. K.: 1990, 'A Perspective on Coherent Structures and Conceptual Models for Turbulent Boundary Layer Physics' AIAA 21st Fluid Dynamics, Plasma Dynamics and Lasers Conference, Seattle, WA, AIAA Pap. No. 90–1638, 16 pp.
Robinson, S. K.: 1991, 'Coherent Motions in the Turbulent Boundary Layer', Annu. Rev. Fluid Mech. 23, 601–639.
Stull, R. B.: 1988, Introduction to Boundary Layer Meteorology, Kluwer Academic Publishers, Norwell, Mass., 666 pp.
Wallace, J. M., Eckelmann, H., and Brodkey, R. S.: 1972, 'The Wall Region in Turbulent Shear Flow', J. Fluid Mech. 54, 39–48.
Wilczak, J. M.: 1984, 'Large-Scale Eddies in the Unstably Stratified Atmospheric Surface Layer. Part I: Velocity and Temperature Structure', J. Atmos. Sci. 41, 3537–3550.
Wilczak, J.M. and Businger, J. A.: 1984, 'Large-Scale Eddies in the Unstably Stratified Atmospheric Surface Layer. Part II: Turbulent Pressure Fluctuations and the Budgets of Heat Flux, Stress and Turbulent Kinetic Energy', J. Atmos. Sci. 41, 3551–3567.
Wilczak, J. M. and Tillman, J. E.: 1980, 'The Three-Dimensional Structure of Convection in the Atmospheric Surface Layer', J. Atmos. Sci. 37, 2424–2443.
Williams, A. G. and Hacker, J. M.: 1992, 'The Composite Shape and Structure of Coherent Eddies in the Convective Boundary Layer', Boundary-Layer Meteorol. 61, 213–245.
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Boppe, R.S., Neu, W.L. & Shuai, H. Large-Scale Motions in the Marine Atmospheric Surface Layer. Boundary-Layer Meteorology 92, 165–183 (1999). https://doi.org/10.1023/A:1001837729368
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DOI: https://doi.org/10.1023/A:1001837729368