• Aubinet, M., B. Heinesch, and M. Yernaux. 2003. Horizontal and vertical CO2 advection in a sloping forest. Bound.-Layer Meteor. 108:397417.

    • Search Google Scholar
    • Export Citation
  • Aylor, D. E. 1999. Biophysical scaling and the passive dispersal of fungus spores: Relationship to integrated pest management strategies. Agric. For. Meteor. 97:275292.

    • Search Google Scholar
    • Export Citation
  • Baldocchi, D. Coauthors 2001. FLUXNET: A new tool to study the temporal and spatial variability of ecosystem-scale carbon dioxide, water vapor, and energy flux densities. Bull. Amer. Meteor. Soc. 82:24152434.

    • Search Google Scholar
    • Export Citation
  • Blair, J. B., D. L. Rabine, and M. A. Hofton. 1999. The laser vegetation imaging sensor: A medium-altitude, digitization-only, airborne laser altimeter for mapping vegetation and topography. ISPRS J. Photogramm. Remote Sens. 54:115122.

    • Search Google Scholar
    • Export Citation
  • Cionco, R. M. 1985. Modeling windfields and surface layer wind profiles over complex terrain and within vegetative canopies. The Forest-Atmosphere Interaction, B. A. Hutchison and B. B. Hicks, Eds., Reidel Publishing, 501–520.

    • Search Google Scholar
    • Export Citation
  • Finnigan, J. J. 1999. A comment on the paper by Lee (1998): On micrometeorological observations of surface-air exchange over tall vegetation. Agric. For. Meteor. 97:5564.

    • Search Google Scholar
    • Export Citation
  • Finnigan, J. J. and S. E. Belcher. 2004. Flow over a hill covered with a plant canopy. Quart. J. Roy. Meteor. Soc. 130:129.

  • Fitzjarrald, D. R. 1984. Katabatic wind in opposing flow. J. Atmos. Sci. 41:11431158.

  • Fitzjarrald, D. R. and K. M. Moore. 1995. Physical mechanisms of heat and mass exchange between forests and the atmosphere. Forest Canopies, M. Lowman and N. Nadkarni, Eds., Academic Press, 45–72.

    • Search Google Scholar
    • Export Citation
  • Fitzmaurice, L., R. H. Shaw, K. T. Paw U, and E. G. Patton. 2004. Three-dimensional microfront systems in a large-eddy simulation of vegetation canopy flow. Bound.-Layer Meteor. 112:107127.

    • Search Google Scholar
    • Export Citation
  • Fleagle, R. G. 1950. A theory of air drainage. J. Meteor. 7:227232.

  • Fujita, T. T. and R. M. Wakimoto. 1982. Effects of miso- and mesoscale obstructions on PAM winds obtained during Project NIMROD. J. Appl. Meteor. 21:840858.

    • Search Google Scholar
    • Export Citation
  • Hunt, J. C. R., K. J. Richards, and P. W. M. Brighton. 1988. Stably stratified shear flow over low hills. Quart. J. Roy. Meteor. Soc. 114:859886.

    • Search Google Scholar
    • Export Citation
  • Kaimal, J. C. and J. J. Finnigan. 1994. Atmospheric Boundary Layer Flows. Oxford University Press, 289 pp.

  • Kaimal, J. C., J. E. Gaynor, H. A. Zimmerman, and G. A. Zimmerman. 1990. Minimizing flow distortion errors in a sonic anemometer. Bound.-Layer Meteor. 53:103115.

    • Search Google Scholar
    • Export Citation
  • Lee, X. 1997. Gravity waves in a forest: A linear analysis. J. Atmos. Sci. 54:25742585.

  • Lee, X. 1998. On micrometeorological observations of surface–air exchange over tall vegetation. Agric. For. Meteor. 91:3949.

  • Lee, X., R. H. Shaw, and T. A. Black. 1994. Modelling the effect of mean pressure gradient on the mean flow within forests. Agric. For. Meteor. 68:201212.

    • Search Google Scholar
    • Export Citation
  • Lee, X., J. D. Fuentes, R. M. Staebler, and H. H. Neumann. 1999. Long-term observation of the atmospheric exchange of CO2 with a temperate deciduous forest in Southern Ontario, Canada. J. Geophys. Res. 104:1597515984.

    • Search Google Scholar
    • Export Citation
  • Mahrt, L. 1982. Momentum balance of gravity flows. J. Atmos. Sci. 39:27012711.

  • Mahrt, L., D. Vickers, R. Nakamura, J. Sun, S. Burns, D. Lenschow, and M. Soler. 2001. Shallow drainage and gully flows. Bound.-Layer Meteor. 101:243260.

    • Search Google Scholar
    • Export Citation
  • Meyers, T. P. and K. T. Paw U. 1986. Testing of a higher-order closure model for airflow within and above plant canopies. Bound.-Layer Meteor. 37:297311.

    • Search Google Scholar
    • Export Citation
  • Moeng, C-H. and D. A. Randall. 1984. Problems in simulation the stratocumulus-topped boundary layer with a third-order model. J. Atmos. Sci. 41:15881600.

    • Search Google Scholar
    • Export Citation
  • Moore, K. E. 1987. Nocturnal spore dispersal in young plantations: A micro-meteorological examination of the nighttime surface layer. Ph.D. dissertation, University at Albany, State University of New York, 103 pp.

  • Moore, K. E., D. R. Fitzjarrald, R. K. Sakai, M. L. Goulden, J. W. Munger, and S. C. Wofsy. 1996. Seasonal variation in radiative and turbulent exchange at a deciduous forest in central Massachusetts. J. Appl. Meteor. 35:122134.

    • Search Google Scholar
    • Export Citation
  • Parker, G. G. and M. E. Russ. 2004. The canopy surface and stand development: Assessing forest canopy structure and complexity with near-surface altimetry. For. Ecol. Manage. 189:307315.

    • Search Google Scholar
    • Export Citation
  • Parker, G. G. Coauthors 2004a. Three dimensional structure of an old-growth Pseudotsuga-Tsuga canopy and its implications for radiation balance, microclimate, and atmospheric gas exchange. Ecosystems 7:440453.

    • Search Google Scholar
    • Export Citation
  • Parker, G. G., D. J. Harding, and M. Berger. 2004b. A portable lidar altimeter system for rapid determination of forest canopy structure. J. Appl. Ecol. 41:755767.

    • Search Google Scholar
    • Export Citation
  • Poggi, D., G. G. Katul, and J. D. Albertson. 2004. Momentum transfer and turbulent kinetic energy budgets within a dense model canopy. Bound.-Layer Meteor. 111:589614.

    • Search Google Scholar
    • Export Citation
  • Prandtl, L. 1942. Führer durch die Ströhmungslehre. (Guide through the Science of Flow). Vieweg und Sohn, 382 pp.

  • 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. 125:1931.

    • Search Google Scholar
    • Export Citation
  • Raupach, M. R. 1989. Stand overstory processes. Philos. Trans. Roy. Soc. London B324:175185.

  • Shaw, R. H. 1977. Secondary wind speed maxima inside plant canopies. J. Appl. Meteor. 16:514521.

  • Smith, F. B., D. J. Carson, and H. R. Oliver. 1972. Mean wind-direction shear through a forest canopy. Bound.-Layer Meteor. 3:178190.

    • Search Google Scholar
    • Export Citation
  • Staebler, R. M. 2003. Forest subcanopy flows and micro-scale advection of carbon dioxide. Ph.D. dissertation, University at Albany, State University of New York, 179 pp.

  • Staebler, R. M. and D. R. Fitzjarrald. 2004. Observing subcanopy CO2 advection. Agric. For. Meteor. 122:139156.

  • Takahashi, A. and T. Hiyama. 2004. A momentum exchange model for the surface layer over bare soil and canopy-covered surfaces. J. Appl. Meteor. 43:14601476.

    • Search Google Scholar
    • Export Citation
  • Wilson, J. D. 1988. A secondary-order closure model for flow through vegetation. Bound.-Layer Meteor. 42:371392.

  • Wilson, K. B. and T. P. Meyers. 2001. The spatial variability of energy and carbon dioxide fluxes at the floor of a deciduous forest. Bound.-Layer Meteor. 98:443473.

    • Search Google Scholar
    • Export Citation
  • Wilson, N. R. and R. H. Shaw. 1977. A higher order closure model for canopy flow. J. Appl. Meteor. 16:11971205.

  • Zeng, P. and H. Takahashi. 2000. A first-order closure model for the wind flow within and above vegetation canopies. Agric. For. Meteor. 103:301313.

    • Search Google Scholar
    • Export Citation
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Measuring Canopy Structure and the Kinematics of Subcanopy Flows in Two Forests

Ralf M. StaeblerAtmospheric Sciences Research Center, University at Albany, State University of New York, Albany, New York

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David R. FitzjarraldAtmospheric Sciences Research Center, University at Albany, State University of New York, Albany, New York

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Abstract

A better understanding of forest subcanopy flows is needed to evaluate their role in the horizontal movement of scalars, particularly in complex terrain. This paper describes detailed measurements of the canopy structure and its variability in both the horizontal and vertical directions at a deciduous forest in complex terrain (the Harvard Forest, Petersham, Massachusetts). The effects of the trunks and subcanopy shrubs on the flow field at each of six subcanopy array locations are quantified. The dynamics of the subcanopy flow are examined with pragmatic methods that can be implemented on a small scale with limited resources to estimate the stress divergence, buoyancy, and pressure gradient forces that drive the flow. The subcanopy flow at the Harvard Forest was driven by mechanisms other than vertical stress divergence 75% of the time. Nocturnal flows were driven predominantly by the negative buoyancy of a relatively cool layer near the forest floor. The direction of the resulting drainage flows followed the azimuth of the longest forest-floor slope. Similar results were found at a much flatter site at Borden, Ontario, Canada. There was no clear evidence of flow reversals in the subcanopy in the lee of ridges or hills at the Harvard Forest even in high wind conditions, contrary to some model predictions.

* Current affiliation: Meteorological Service of Canada, Toronto, Ontario, Canada

Corresponding author address: Ralf Staebler, Air Quality Research Branch, Meteorological Service of Canada, 4905 Dufferin St., Toronto, ON M3H 5T4, Canada. ralf.staebler@ec.gc.ca

Abstract

A better understanding of forest subcanopy flows is needed to evaluate their role in the horizontal movement of scalars, particularly in complex terrain. This paper describes detailed measurements of the canopy structure and its variability in both the horizontal and vertical directions at a deciduous forest in complex terrain (the Harvard Forest, Petersham, Massachusetts). The effects of the trunks and subcanopy shrubs on the flow field at each of six subcanopy array locations are quantified. The dynamics of the subcanopy flow are examined with pragmatic methods that can be implemented on a small scale with limited resources to estimate the stress divergence, buoyancy, and pressure gradient forces that drive the flow. The subcanopy flow at the Harvard Forest was driven by mechanisms other than vertical stress divergence 75% of the time. Nocturnal flows were driven predominantly by the negative buoyancy of a relatively cool layer near the forest floor. The direction of the resulting drainage flows followed the azimuth of the longest forest-floor slope. Similar results were found at a much flatter site at Borden, Ontario, Canada. There was no clear evidence of flow reversals in the subcanopy in the lee of ridges or hills at the Harvard Forest even in high wind conditions, contrary to some model predictions.

* Current affiliation: Meteorological Service of Canada, Toronto, Ontario, Canada

Corresponding author address: Ralf Staebler, Air Quality Research Branch, Meteorological Service of Canada, 4905 Dufferin St., Toronto, ON M3H 5T4, Canada. ralf.staebler@ec.gc.ca

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