# Estimation of surface heat and momentum fluxes using the flux-variance method above uniform and non-uniform terrain

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## Abstract

Eddy-correlation measurements above an uneven-aged forest, a uniform-irrigated bare soil field, and within a grass-covered forest clearing were used to investigate the usefulness of the fluxvariance method above uniform and non-uniform terrain. For this purpose, the Monin and Obukhov (1954) variance similarity functions were compared with direct measurements. Such comparisons were in close agreement for momentum and heat but not for water vapor. Deviations between measured and predicted similarity functions for water vapor were attributed to three factors: 1) the active role of temperature in surface-layer turbulence, 2) dissimilarity between sources and sinks of heat and water vapor at the ground surface, and 3) the non-uniformity in water vapor sources and sinks. It was demonstrated that the latter non-uniformity contributed to horizontal gradients that do not scale with the vertical flux. These three factors resulted in a turbulence regime that appeared more efficient in transporting heat than water vapor for the dynamic convective sublayer but not for the dynamic sublayer. The agreement between eddy-correlation measured and flux-variance predicted sensible heat flux was better than that for latent heat flux at all three sites. The flux-variance method systematically overestimated the latent heat flux when compared to eddy-correlation measurements. It was demonstrated that the non-uniformity in water vapor sources reduced the surface flux when compared to an “equivalent” uniform terrain subjected to identical shear stress, sensible heat flux, and atmospheric water vapor variance. Finally, the correlation between the temperature and water vapor fluctuations was related to the relative efficiency of surface-layer turbulence in removing heat and water vapor. These relations were used to assess critical assumptions in the derivation of the flux-variance formulation.

## Keywords

Water Vapor Latent Heat Flux Atmospheric Water Vapor Identical Shear Water Vapor Source## Preview

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## References

- Albertson, J. D., Parlange, M. B., Katul, G. G., Chu, C. R., Stricker, H., and Tyler, S.: 1994, ‘Modeling Sensible Heat Flux from Arid Regions Using a Simple Flux-Variance Method’, In press,
*Water Resourc. Res.*Google Scholar - Brutsaert, W.: 1982,
*Evaporation into the Atmosphere: Theory, History, and Applications*, D. Reidel, Dordecht, Holland, 299 pp.Google Scholar - Brutsaert, W., and Parlange, M. B.: 1992, ‘The Unstable Surface Layer above Forest-Regional Evaporation and Heat Flux’,
*Water Resourc. Res.***28**, 3129–3134.Google Scholar - de Bruin, H. A. R.: 1994, ‘Analytic Solutions of the Equations Governing the Temperature Fluctuation Method’,
*Boundary-Layer Meteorol.***68**, 427–432.Google Scholar - de Bruin, H. A. R., Kohsiek, W., and Van Den Hurk, B. J. J. M.: 1993, ‘A Verification of Some Methods to Determine the Fluxes of Momentum, Sensible Heat, and Water Vapor Using Standard Deviation and Structure Parameter of Scalar Meteorological Quantities’,
*Boundray-Layer Meteorol.***63**, 231–257.Google Scholar - de Bruin, H. A. R., Bink, N. I., and Kroon, L. J. M.: 1991, ‘Fluxes in the Surface Layer Under Advective Conditions’, in T. J. Schmugge and J. C. André (eds.),
*Workshop on Land Surface Evaporation Measurement and Parameterization*, Springer-Verlag, New York, pp. 157–169.Google Scholar - Hill, R. J.: 1989, ‘Implications of Monin and Obukhov Similarity Theory for Scalar Quantities’,
*J. Atmos. Sci.***46**, 2236–2244.Google Scholar - Hogg, R. V. and Craig, A. T.: 1978,
*Introduction to Mathematical Statistics*, Fourth Edition, Macmillan Publishing Co., 438 pp.Google Scholar - Garratt, J. R.: 1992,
*The Atmospheric Boundary Layer*, Cambridge University Press, 316 pp.Google Scholar - Guan, Z.: 1991, ‘Ozone Deposition to a Coniferous Forest’, Ph.D., University of Maine.Google Scholar
- Kader, B. A. and Yaglom, A. M.: 1990, ‘Mean Fields and Fluctuation Moments in Unstably Stratified Turbulent Boundary Layers’,
*J. Fluid Mech.***212**, 637–662.Google Scholar - Kaimal, J. C. and Finnigan, J. J.: 1994,
*Atmospheric Boundary Layer Flows, Their Structure and Measurements*, Oxford University Press, 289 pp.Google Scholar - Katul, G. G.: 1994, ‘A Model for Sensible Heat Flux Probability Density Function for Near-Neutral and Slightly-Stable Atmospheric Flows’,
*Boundary-Layer Meteorol.***71**, 1–20.Google Scholar - Katul, G. G. and Parlange, M. B.: 1992, ‘An Atmospheric Stability Penman-Brutsaert Potential Evaporation Model’,
*Water Resourc. Res.***28**, 121–126.Google Scholar - Katul, G. G. and Parlange, M. B.: 1994, ‘On the Active Role of Temperature in Surface Layer Turbulence’,
*J. Atmos. Sci.***51**, 2181–2195.Google Scholar - Katul, G. G., Parlange, M. B., and Chu, C. R.: 1994, ‘Intermittency, Local Isotropy, and Non-Gaussian Statistics in Atmospheric Surface Layer Turbulence’,
*Phys. Fluids***6**, 2480–2492.Google Scholar - Lang, A. R. G., McNaughton, K. G., Bradley, E. F., Chen Fazu, and Ohtaki, Eiji: 1983, ‘Inequality of Eddy Transfer Coefficients for Vertical Transport of Sensible and Latent Heats during Advective Inversions’,
*Boundary-Layer Meteorol.***25**, 25–41.Google Scholar - Lloyd, C. R., Culf, A. D., Dolman, A. J., and Gash, J. H.: 1991, ‘Estimates of Sensible Heat Flux from Observations of Temperature Fluctuations’,
*Boundary-Layer Meteorol.***57**, 311–322.Google Scholar - Lumley, J. and Panofsky, H.: 1964,
*The Structure of Atmospheric Turbulence*, John Wiley and Sons, 239 pp.Google Scholar - Lumley, J.: 1970,
*Stochastic Tools in Turbulence*, Academic Press, 195 pp.Google Scholar - McBean, G. A., and Miyake, M.: 1972, ‘Turbulent Transfer Mechanisms in the Atmospheric Surface Layer’,
*Quart. J. Roy. Meteorol. Soc.***98**, 383–398.Google Scholar - McMillen, R. T.: 1986, ‘A BASIC Program for Eddy Correlation in Non-Simple Terrain’,
*NOAA Technical Memorandum ERL ARL-147*, 32 pp.Google Scholar - Merry, M. and Panofsky, H. A.: 1976, ‘Statistics of Vertical Motion Over Land and Water’,
*Q. J. R. Meteorol. Soc.***102**, 255–260.Google Scholar - Monin, A. S. and Yaglom, A. M.: 1971, in J. Lumley (ed.),
*Statistical Fluid Mechanics*, Vol. 1, MIT Press, 769 pp.Google Scholar - Monin, A. S. and Obukhov, A. M.: 1954, ‘Basic Laws of Turbulent Mixing in the Ground Layer of the Atmosphere’,
*Tr. Geofiz. Inst. Akad. Nauk. SSSR***151**, 163–187.Google Scholar - Ohtaki, E.: 1985, ‘On the Similarity in Atmospheric Fluctuations of Carbon Dioxide, Water Vapor and Temperature over Vegetated Fields’,
*Boundary-Layer Meteorol.***2**, 25–37.Google Scholar - Padro, J.: 1993, ‘An Investigation of Flux-Variance Methods and Universal Functions Applied to Three Land-Use Types in Unstable Conditions’,
*Boundary-Layer Meteorol.***66**, 413–425.Google Scholar - Panofsky, H. and Dutton, J.: 1984,
*Atmospheric Turbulence: Models and Methods for Engineering Applications*, John Wiley and Sons, 397 pp.Google Scholar - Parlange, M. B., Katul, G. G., Cuenca, R. H., Levent Kavvas, M., Nielsen, D. R., and Mata, M.: 1992, ‘Physical Basis for a Time Series Model of Soil Water Content’,
*Water Resourc. Res.***28**, 2437–2446.Google Scholar - Parlange, M. B. and Brutsaert, W.: 1993, ‘Regional Shear Stress of Broken Forest from Radiosonde Wind Profiles in the Unstable Surface Layer’,
*Boundary-Layer Meteorol.***64**, 355–368.Google Scholar - Priestley, J. T. and Hill, R. J.: 1985, ‘Measuring High-Frequency Humidity, Temperature and Radio Refractive Index in the Surface Layer’,
*J. Atmos. and Ocean. Tech.***2**, 233–251.Google Scholar - Raupach, M.: 1993, ‘The Averaging of Surface Flux Densities in Heterogeneous Landscapes’,
*Exchange Processes at the Land Surface for a Range of Space and Time Scales*, in*Proceedings of the Yokahama Symposium*, July, IAHS Publ. no. 212.Google Scholar - Stull, R.: 1988,
*An Introduction to Boundary Layer Meteorology*, Kluwer Academic Press, 666 pp.Google Scholar - Tennekes, H. and Lumley, J.: 1972,
*A First Course in Turbulence*, MIT Press, 300 pp.Google Scholar - Tillman, J. E.: 1972, ‘The Indirect Determination of Stability, Heat and Momentum Fluxes in the Atmospheric Boundary Layer from Simple Scalar Variables During Dry Unstable Conditions’,
*J. Appl. Meteorol.***11**, 783–792.Google Scholar - Warhaft, Z.: 1976, ‘Heat and Moisture Fluxes in the Stratified Boundary Layer’,
*Quart. J. Roy. Meteorol. Soc.***102**, 703–706.Google Scholar - Weaver, H. L.: 1990, ‘Temperature and Humidity Flux-Variance Relations Determined by One-Dimensional Eddy Correlations’,
*Boundary-Layer Meteorol.***53**, 77–91.Google Scholar - Wesely, M. L.: 1988, ‘Use of Variance Techniques to Measure Dry Air-Surface Exchange Rates’,
*Boundary-Layer Meteorol.***44**, 13–31.Google Scholar - Wyngaard, J. C., Coté, O. R., and Izumi, Y.: 1971, ‘Local Free Convection, Similarity and the Budgets of Shear Stress and Heat Flux’,
*J. Atmos. Sci.***28**, 1171–1182.Google Scholar