Atmosphere (대기)

Korean Meteorological Society (한국기상학회)
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Characteristics of Wind Direction Shear and Momentum Fluxes within Roughness Sublayer over Sloping Terrain

경사가 있는 지형의 거칠기 아층에서 풍향시어와 운동량 플럭스의 특성

  • Lee, Young-Hee (Department of Astronomy and Atmospheric Sciences, Kyungpook National University)
  • 이영희 (경북대학교 천문대기과학과)
  • Received : 2015.03.13
  • Accepted : 2015.10.05
  • Published : 2015.12.31
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Abstract

We have analyzed wind and eddy covariance data collected within roughness sublayer over sloping terrain. The study site is located on non-flat terrain with slopes in both south-north and east-west directions. The surface elevation change is smaller than the height of roughness element such as building and tree. This study examines the directional wind shear for data collected at three levels in the lowest 10 m in the roughness sublayer. The wind direction shear is caused by drag of roughness element and terrain-induced motions at this site. Small directional shear occurs when wind speed at 10 m is strong and wind direction at 10 m is southerly which is the same direction as upslope flow near surface at this site during daytime. Correlation between vertical shear of lateral momentum and lateral momentum flux is smaller over steeply sloped surface compared to mildly sloped surface and lateral momentum flux is not down-gradient over steeply sloped surface. Quadrant analysis shows that the relative contribution of four quadrants to momentum flux depends on both surface slope and wind direction shear.

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References

  1. Bowen, B. M., J. A. Baars, and G. L. Stone, 2000: Nocturnal wind direction shear and its potential impact on pollutant transport. J. Appl. Meteorol., 39, 437-445. https://doi.org/10.1175/1520-0450(2000)039<0437:NWDSAI>2.0.CO;2
  2. Christen, A., E. van Gorsel, and R. Vogt, 2007: Coherent structures in urban roughness sublayer turbulence. Int. J. Climatol., 27, 1955-1968. https://doi.org/10.1002/joc.1625
  3. Dupont, S., and E. G. Patton, 2012: Momentum and scalar transport within a vegetation canopy following atmospheric stability and seasonal canopy changes: The CHATS experiment. Atmos. Chem. Phys., 12, 5913-5935. https://doi.org/10.5194/acp-12-5913-2012
  4. Finnigan, J. J., and S. E. Belcher, 2004: Flow over a hill covered with a plant canopy. Quart. J. Roy. Meteor. Soc., 130, 1-29. https://doi.org/10.1256/qj.02.177
  5. Gao, W., R. H. Shaw, and K. T. Paw U, 1989: Observation of organized structure in turbulent flow within and above a forest canopy. Bound.-Layer Meteor., 47, 349-377. https://doi.org/10.1007/BF00122339
  6. Kaimal, J. C., and J. J. Finnigan, 1994: Atmospheric boundary layer Flows: Their structure and measurement. Oxford University Press, 289 pp.
  7. Katul, G. G., and J. D. Albertson, 1998: An investigation of higher-order closure models for a forested canopy. Bound.-Layer Meteor., 89, 47-74. https://doi.org/10.1023/A:1001509106381
  8. Leclerc, M. Y., K. C. Beissner, R. H. Shaw, G. D. Hartog, and H. H. Neumann, 1991: The influence of buoyancy on third-order turbulent velocity statistics within a deciduous forest. Bound-Layer Meteor., 55, 109-123. https://doi.org/10.1007/BF00119329
  9. Lee, X., W. Massman, and B. Law, 2004: Handbook of Micrometeorology. Kluwer Academic Publishers, 250 pp.
  10. Lee, Y., 2009: The influence of local stability on heat and momentum transfer within open canopies. Bound.-Layer Meteor., 132, 383-399. https://doi.org/10.1007/s10546-009-9405-3
  11. Lee, Y., 2012: Influence of non-flat terrain and wind direction shear on canopy turbulence. Asia.-Pacific J. Atmos. Sci., 48, 243-252. https://doi.org/10.1007/s13143-012-0024-4
  12. Mahrt, L., 2000: Surface heterogeneity and vertical structure of the boundary layer. Bound.-Layer Meteor., 96, 33-62. https://doi.org/10.1023/A:1002482332477
  13. Mahrt, L., S. Richardson, D. Stauffer, and N. Seaman, 2014: Nocturnal wind-directional shear in complex terrain. Quart. J. Roy. Meteor. Soc., 140, 2393-2400. https://doi.org/10.1002/qj.2369
  14. Pyles, R. D., K. T. Paw U, and M. Falk, 2004: Directional wind shear within an old-growth temperate rainforest: observations and model results. Agric. For. Meteor., 125, 19-31. https://doi.org/10.1016/j.agrformet.2004.03.007
  15. Raupach, M. R., 1981: Conditional statistics of Reynolds stress in rough-wall and smooth-wall turbulent boundary layers. J. Fluid Mech., 108, 363-382. https://doi.org/10.1017/S0022112081002164
  16. Raupach, M. R., J. J. Finnigan, and Y. Brunet, 1996: Coherent eddies and turbulence in vegetation canopies: the mixing-layer analogy. Bound.-Layer Meteor., 78, 351-382. https://doi.org/10.1007/BF00120941
  17. Stull, R. B., 1988: An introduction to boundary layer meteorology. Kluwer, 670 pp.
  18. Su, H. B., H. P. Schmid, C. S. Vogel, and P. S. Curtis, 2008: Effects of canopy morphology and thermal stability on mean flow and turbulence statistics observed inside a mixed hardwood forest. Agric. For. Meteor., 148, 862-882. https://doi.org/10.1016/j.agrformet.2007.12.002
  19. Wilczak, J. M., S. P. Oncley, and S. A. Stage, 2001: Sonic anemometer tilt correction algorithms. Bound.-Layer Meteor., 99, 127-150. https://doi.org/10.1023/A:1018966204465

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