Skip to main content
SpringerLink
Log in

Spatial variability of turbulent fluxes and roughness lengths in HAPEX-MOBILHY

  • Published:
Boundary-Layer Meteorology Aims and scope Submit manuscript

Abstract

Surface-based and aircraft measured fluxes over the heterogeneous surface in HAPEX-MOBILHY are analyzed for the ten flight days when cloud cover above the boundary layer was minimal. The fair-weather climatology of the spatial variation of surface fluxes is estimated to provide an assessment of the generality of previous case studies appearing in the literature. For the 10-day averages, greater heating over the forest generates a forest breeze which leads to rising motion and a modest increase of boundary-layer cloud cover at the forest edge. The exchange coefficients and effective roughness lengths are computed for local averages (15 km scale) and for regional averages (100 km scale) intended to represent a range of grid sizes in numerical models of the atmosphere. The effective roughness length for momentum over the mixed agricultural region for both scales is on the order of 1 m, apparently due to bluff roughness effects associated with scattered trees, edges of small woods and other obstacles. This roughness length value is an order of magnitude larger than values used in numerical models for the same region, which are based on the dominant vegetation type. The spatially varying effective roughness length for heat is computed for use in those models which use surface radiation temperature to estimate surface heat flux. The effective roughness lengths for heat are found to be smaller than those typically used in numerical models of the atmosphere.

This is a preview of subscription content, log in via an institution to check access.

Access this article

Log in via an institution

Price excludes VAT (USA)
Tax calculation will be finalised during checkout.

Instant access to the full article PDF.

Institutional subscriptions

Similar content being viewed by others

References

  • André, J. C. and collaborators: 1988, ‘Evaporation Over Land-Surfaces, First Results from HAPEX-MOBILHY Special Observing Period’,Ann. Geophys. B 6, 477–492.

    Google Scholar 

  • André, J. C., Bougeault, P., Mafouf, J.-F., Mascart, P., Noihan, J., and Pinty, J.-P.: 1989, ‘Impact of Forests on Mesoscale Meteorology’,Phil. Trans. R. Soc. Lond. B324, 407–422.

    Google Scholar 

  • André, J.-C., Bougeault, P. and Goutorbe, J.-P.: 1990 ‘Regional Estimates of Heat and Evaporation Fluxes Over Non-Homogeneous Terrain, Examples from the HAPEX-MOBILHY Programme’,Boundary-Layer. Meteorol. 50, 77–108.

    Google Scholar 

  • Bechtold, P., Pinty, J.-P., and Mascart, P.: 1993, ‘A Numerical Investigation of the Influence of Large-Scale Winds on Sea Breeze and Inland Breeze Type Circulations’, to appear inJ. Appl. Meteorol.

  • Beljaars, A. C. M., and Holtslag, A. A. M.: 1991, ‘Flux Parameterization Over Land Surfaces for Atmospheric Models’,j. Appl. Meteorol. 30, 327–341.

    Google Scholar 

  • Ben Mehrez, M., Taconet, O., Vidal-Madjar, D., and Sucksdorff, Y.: 1992, ‘Calibration of an Energy Flux Model Over Bare Soils During the HAPEX-MOBILHY Experiment’,Agric. For. Meteorol. 58, 257–283.

    Google Scholar 

  • Bougeault, P., Bret, B., Lacarrère, P., and Noilhan, J.: 1991, ‘An Experiment with an Advanced Surface Parameterization in a Mesobeta-Scale Model, Part II: The 16 June 1986 Simulation’,Mon. Wea. Rev. 119, 2374–2392.

    Google Scholar 

  • Bradley, E. F.: 1968, ‘A Micrometeorological Study of Velocity Profiles and Surface Drag in the Region Modified by a Change in Surface Roughness’,Quart. J. Roy. Meteorol. Soc. 94, 361–379.

    Google Scholar 

  • Brutsaert, W. H.: 1982,Evaporation into the Atmosphere, D. Reidel, Dordrecht, 299 pp.

    Google Scholar 

  • Claussen, Martin: 1990, ‘Area-Averaging of Surface Fluxes in a Neutrally Stratified, Horizontally Inhomogeneous Atmospheric Boundary Layer’,Atmos. Envir. 24A, 1349–1360.

    Google Scholar 

  • Claussen, Martin: 1992, ‘Scale Aggregation in Semi-Smooth Flow’, submitted toJ. of Hydrology. Also Report No. 87, Max-Planck-Institut für Meteorologie, Bundesstr. 55, 2 Hamburg 13, Germany.

  • Claussen, Martin and Klaassen, Wim: 1992, ‘On Regional Surface Fluxes Over Partly Forested Areas’,Contributions to Atmospheric Physics 65, 243–248.

    Google Scholar 

  • Fazu, Chen and Schwerdtfeger, Peter: 1989, ‘Flux-Gradient Relationships for Momentum and Heat Over a Rough Natural Surface’,Q. J. Roy. Meteorol. Soc. 115, 335–352.

    Google Scholar 

  • Garratt, J. R.: 1980, ‘Surface Influence Upon Vertical Profiles in the Atmospheric Near-Surface Layer’,Q. J. R. Meteorol. Soc. 106, 803–819.

    Google Scholar 

  • Garratt, J. R.: 1992,The Atmospheric Boundary Layer, Cambridge University Press, 316 pp.

  • Garratt, J. R. and Hicks, B. B.: 1973, ‘Momentum, Heat and Water Vapour Transfer to and from Natural and Artificial Surfaces’,Q. J. Roy. Meteorol. Soc. 99, 680–687.

    Google Scholar 

  • Garratt, J. R., Peilke, R. A., Miller, W. F., and Lee, T. J.: 1990, ‘Mesoscale Model Response to Random Surface-Based Perturbations — a Sea-Breeze Experiment’,Boundary-Layer Meteorol. 52, 313–334.

    Google Scholar 

  • Gash, J. H. C., Shuttleworth, W. J., Lloyd, C. R., André, J.-C., Goutorbe, J.-P., and Gelpe, J.: 1989, ‘Micrometeorological Measurements in Les Landes Forest During HAPEX-MOBILHY’,Agric. For. Meteorol. 46, 131–147.

    Google Scholar 

  • Goutorbe, J.-P.: 1991, ‘A Critical Assessment of the SAMER Network Accuracy’, in Thomas J. Schmugge and Jean-Claude André (eds.),Land Surface Evaporation. Measurement and Parameterization, Springer Verlag, pp. 171–182.

  • Grant, A. L. M.: 1991, ‘Surface Drag and Turbulence Over an Inhomogeneous Land Surface’,Boundary-Layer Meteorol. 56, 309–337.

    Google Scholar 

  • Hadfield, M. G., Cotton, W. R., and Pielke, R. A.: 1992, ‘Large-Eddy Simulations of Thermally Forced Circulations in the Convective Boundary Layer’, Part II: ‘The Effect of Changes in Wavelength and Wind Speed’,Boundary-Layer Meteorol. 58, 307–327.

    Google Scholar 

  • Hildebrand, P. H.: 1988, ‘Flux and Sounding Data from the NCAR King Air Aircraft During HAPEX’, NCAR Technical Rept. TN-319, NCAR Boulder, CO 80307, USA.

    Google Scholar 

  • Hildebrand, P. H.: 1991, ‘Errors in Eddy Correlation Turbulence Measurements from Aircraft: Application to HAPEX-MOBILHY’, in Thomas J. Schmugge and Jean-Claude André (eds.),Land Surface Evaporation. Measurement and Parameterization, Springer Verlag, pp. 231–243.

  • Klaassen, W.: 1992, ‘Average Fluxes from Heterogeneous Vegetated Regions’,Boundary-Layer Meteorol. 58, 329–354.

    Google Scholar 

  • Louis, J.-F.: 1979, ‘A Parametric Model of Vertical Eddy Fluxes in the Atmosphere’,Boundary-Layer Meteorol. 17, 187–202.

    Google Scholar 

  • Mahrt, L.: 1987, ‘Grid-Averaged Surface Fluxes’,Mon. Wea. Rev. 115, 1550–1560.

    Google Scholar 

  • Mahrt, L.: 1991a, ‘Heat and Moisture Fluxes Over the Pine Forest in HAPEX’, in Thomas J. Schmugge and Jean-Claude André (eds.),Land Surface Evaporation. Measurement and Parameterization, Springer Verlag, pp. 261–273.

  • Mahrt, L.: 1991b, ‘Boundary-Layer Moisture Regimes’,Quart. J. Roy. Meteorol. Soc. 117, 151–176.

    Google Scholar 

  • Mahrt, L. and Gibson, Wayne: 1992, ‘Flux Decomposition into Coherent Structures’,Boundary-Layer Meteorol. 60, 143–168.

    Google Scholar 

  • Mascart, P., Taconet, O., Pinty, J.-P., and Ben Mehrez, M.: 1991, ‘Canopy Resistance Formulation and its Effect in Mesoscale Models, a HAPEX Perspective’,Agric. For. Meteorol. 54, 319–351.

    Google Scholar 

  • Mason, P. J.: 1988, ‘The Formation of Areally-Averaged Roughness Lengths’,Quart. J. Roy. Meteorol. Soc. 114, 399–420.

    Google Scholar 

  • Mazaudier, C. and Weill, A.: 1989, ‘A Method of Determination of Dynamic Influence of the Forest on the Boundary Layer Using Two Doppler Sodars’,J. Appl. Meteorol. 28, 705–710.

    Google Scholar 

  • Noihan, J., Lacarrère, P., and Bougeault, P.: 1991, ‘An Experiment with an Advanced Surface Parameterization in a Mesobeta-Scale Model, Part III: Comparison with the HAPEX-MOBILHY Dataset’,Mon. Wea. Rev. 119, 2393–2413.

    Google Scholar 

  • Parlange, M. 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 

  • Parlange, M. and Brutsaert, W.: 1989, ‘Regional Roughness of the Landes Forest and Surface Shear Stress Under Neutral Conditions’,boundary-Layer Meteorol. 48, 69–81.

    Google Scholar 

  • Paulson, C. A.: 1970, ‘The Mathematical Representation of Wind Speed and Temperature Profiles in the Unstable Atmospheric Surface Layer’,J. Appl. Meteorol. 9, 857–861.

    Google Scholar 

  • Pinty, J.-P., Mascart, P., Richard, E., and Rosset, R.: 1989, ‘An Investigation of Mesoscale Flows Induced by Vegetation Inhomogeneities Using an Evapotranspiration Model Calibrated Against HAPEX-MOBILHY Data’,J. Appl. Meteorol. 28, 976–992.

    Google Scholar 

  • Raupach, M. R.: 1979, ‘Anomalies in Flux-Gradient Relationships Over Forest’,Boundary-Layer Meteorol. 16, 467–486.

    Google Scholar 

  • Raupach, M. R.: 1992, ‘Drag and Drag Partition on Rough Surfaces’,Boundary-Layer Meteorol. 60, 375–395.

    Google Scholar 

  • Segal, M., Schreiber, W. E., Kallos, G., Garratt, J. R., Rodi, A., Weaver, J., and Pielke, R. A.: 1989, ‘The Impact of Crop Areas in Northeast Colorado on Midsummer Mesoscale Thermal Circulations’,Mon. Wea. Rev. 117, 809–825.

    Google Scholar 

  • Segal, M., and Arritt, R. W.: 1992, ‘Non-Classical Mesoscale Circulations Caused by Surface Sensible Heat Flux Gradients’,Bull. Amer. Meteorol. Soc. 73, 1593–1604.

    Google Scholar 

  • Shuttleworth, W. J., Gash, J. H. C., Lloyd, C. R., McNeill, D. D., Moore, C. J., and Wallace, J. S.: 1988, ‘An Integrated Micrometeorological System for Evaporation Measurement’,Agric. For. Meteorol. 43, 295–317.

    Google Scholar 

  • Shuttleworth, W. J.: 1991, ‘Insight from Large-Scale Observational Studies of Land/Atmosphere Interactions’,Surveys in Geophys. 12, 3–30.

    Google Scholar 

  • Taylor, P. A.: 1987, ‘Comments and Further Analysis on the Effective Roughness Length for Use in Numerical Three-Dimensional Models’,Boundary-Layer Meteorol. 39, 403–419.

    Google Scholar 

  • Taylor, P. A., Sykes, R. I., and Mason, P. J.: 1989, ‘On the Parameterization of Drag Over Small-Scale Topography in Neutrally-Stratified Boundary-Layer Flow’,Boundary-Layer Meteorol. 48, 409–422.

    Google Scholar 

  • Wieringa, J.: 1986, ‘Roughness-Dependent Geographical Interpolation of Surface Wind Speed Averages’,Quart. J. Roy. Meteorol. Soc. 112, 867–889.

    Google Scholar 

  • Wieringa, J.: 1992, ‘Updating the Davenport Roughness Classification’,J. Wind Engin. Industr. Aerodyn. 41, 357–368.

    Google Scholar 

  • Wood, N. and Mason, P. J.: 1991, ‘The Influence of Static Stability on the Effective Roughness Lengths for Momentum and Heat Transfer’,Q. J. Roy. Meteorol. Soc. 117, 1025–1056.

    Google Scholar 

Download references

Author information

Authors and Affiliations

  1. Oceanic and Atmospheric Sciences, Oregon State University, 97331, Corvallis, OR, USA

    L. Mahrt & M. EK

Authors
  1. L. Mahrt
    View author publications

    You can also search for this author in PubMed Google Scholar

  2. M. EK
    View author publications

    You can also search for this author in PubMed Google Scholar

Rights and permissions

Reprints and permissions

About this article

Cite this article

Mahrt, L., EK, M. Spatial variability of turbulent fluxes and roughness lengths in HAPEX-MOBILHY. Boundary-Layer Meteorol 65, 381–400 (1993). https://doi.org/10.1007/BF00707034

Download citation

  • Revised:

  • Issue Date:

  • DOI: https://doi.org/10.1007/BF00707034

Keywords

Search

Navigation