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Determining Near-Surface Soil Heat Flux Density Using the Gradient Method: A Thermal Conductivity Model–Based Approach

Determining Near-Surface Soil Heat Flux Density Using the Gradient Method: A Thermal Conductivity... AbstractIn the gradient method, soil heat flux density at a known depth G is determined as the product of soil thermal conductivity λ and temperature T gradient. While measuring λ in situ is difficult, many field studies readily support continuous, long-term monitoring of soil T and water content θ in the vadose zone. In this study, the performance of the gradient method is evaluated for estimating near-surface G using modeled λ and measured T. Hourly λ was estimated using a model that related λ to θ, soil bulk density ρb, and texture at 2-, 6-, and 10-cm depths. Soil heat flux Gm was estimated from modeled λ and measured T gradient (from thermocouples). The Gm results were evaluated with heat flux data GHP determined using independent measured λ and T gradient from heat-pulse probes. The λ model performed well at the three depths with 3.3%–7.4% errors. The Gm estimates were similar to GHP (agreed to within 15.1%), with the poorest agreement at the 2-cm soil depth, which was caused mainly by the relatively greater variability in ρb. Accounting for temporal variations in ρb (with core method) improved the accuracies of λ and Gm at the 2-cm depth. Automated θ monitoring approaches (e.g., time domain reflectometry), rather than gravimetric sampling, captured the temporal dynamics of near-surface λ and G well. It is concluded that with continuous θ and T measurements, the λ model–based gradient method can provide reliable near-surface G. Under conditions of soil disturbance or deformation, including temporally variable ρb, data improves the accuracy of G data. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Journal of Hydrometeorology American Meteorological Society

Determining Near-Surface Soil Heat Flux Density Using the Gradient Method: A Thermal Conductivity Model–Based Approach

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Publisher
American Meteorological Society
Copyright
Copyright © American Meteorological Society
ISSN
1525-7541
DOI
10.1175/JHM-D-16-0290.1
Publisher site
See Article on Publisher Site

Abstract

AbstractIn the gradient method, soil heat flux density at a known depth G is determined as the product of soil thermal conductivity λ and temperature T gradient. While measuring λ in situ is difficult, many field studies readily support continuous, long-term monitoring of soil T and water content θ in the vadose zone. In this study, the performance of the gradient method is evaluated for estimating near-surface G using modeled λ and measured T. Hourly λ was estimated using a model that related λ to θ, soil bulk density ρb, and texture at 2-, 6-, and 10-cm depths. Soil heat flux Gm was estimated from modeled λ and measured T gradient (from thermocouples). The Gm results were evaluated with heat flux data GHP determined using independent measured λ and T gradient from heat-pulse probes. The λ model performed well at the three depths with 3.3%–7.4% errors. The Gm estimates were similar to GHP (agreed to within 15.1%), with the poorest agreement at the 2-cm soil depth, which was caused mainly by the relatively greater variability in ρb. Accounting for temporal variations in ρb (with core method) improved the accuracies of λ and Gm at the 2-cm depth. Automated θ monitoring approaches (e.g., time domain reflectometry), rather than gravimetric sampling, captured the temporal dynamics of near-surface λ and G well. It is concluded that with continuous θ and T measurements, the λ model–based gradient method can provide reliable near-surface G. Under conditions of soil disturbance or deformation, including temporally variable ρb, data improves the accuracy of G data.

Journal

Journal of Hydrometeorology – American Meteorological Society

Published: Aug 15, 2017

References

  • Soil thermal conductivity: Effects of density, moisture, salt concentration, and organic matter
    Abu-Hamdeh, N. H.; Reeder, R. C.
  • Temporal and spatial variability of soil bulk density and near-saturated hydraulic conductivity under two contrasted tillage management systems
    Alletto, L.; Yves, C.
  • Modelling soil thermal conductivities over a wide range of conditions
    Balland, V.; Arp, P.
  • Measurement of thermal properties and water content of unsaturated sandy soil using dual-probe heat-pulse probes
    Bristow, K. L.
  • Test of a heat-pulse probe for measuring changes in soil water content
    Bristow, K. L.; Campbell, G. S.; Calissendorff, C.
  • Probe for measuring soil specific heat using a heat-pulse method
    Campbell, G. S.; Calissendorff, C.; Williams, J. H.
  • Soil heat and water flow with a partial surface mulch
    Chung, S. O.; Horton, R.
  • In situ measurement of soil heat flux with the gradient method
    Cobos, D. R.; Baker, J. M.
  • A generalized thermal conductivity model for soils and construction materials
    Côté, J.; Konrad, J. M.
  • A particle batch smoother for soil moisture estimation using soil temperature observations
    Dong, J.; Steele-Dunne, S. C.; Judge, J.; van de Giesen, N.
  • Soil profile method for soil thermal diffusivity, conductivity and heat flux: Comparison to soil heat flux plates
    Evett, S. R.; Agam, N.; Kustas, W. P.; Colaizzi, P. D.; Schwartz, R. C.
  • Estimation of land surface water and energy balance parameters using conditional sampling of surface states
    Farhadi, L.; Entekhabi, D.; Salvucci, G.; Sun, J.
  • Systematic errors in ground heat flux estimation and their correction
    Gentine, P.; Entekhabi, D.; Heusinkveld, B.
  • Accounting for time-variable soil porosity improves the accuracy of the gradient method for estimating soil carbon dioxide production
    Han, W.; Gong, Y.; Ren, T.; Horton, R.
  • Sensible heat observations reveal soil-water evaporation dynamics
    Heitman, J. L.; Horton, R.; Sauer, T. J.; DeSutter, T. M.
  • Latent heat in soil heat flux measurements
    Heitman, J. L.; Horton, R.; Sauer, T. J.; Ren, T.; Xiao, X.
  • A background temperature correction for thermal conductivity probes
    Jury, W. A.; Bellantuoni, B.
  • Soil-heat flux determination: Temperature gradient method with computed thermal conductivities
    Kimball, B. A.; Jackson, R. D.; Nakayama, F. S.; Idso, S. B.; Reginato, R. J.
  • An adiabatic boundary condition solution for improved accuracy of heat-pulse measurement analysis near the soil–atmosphere interface
    Liu, G.; Zhao, L.; Wen, M.; Chang, X.; Hu, K.
  • Determination of soil bulk density with thermo–time domain reflectometry sensors
    Liu, X.; Ren, T.; Horton, R.
  • In situ monitoring of soil bulk density with a thermo-TDR sensor
    Liu, X.; Lu, S.; Horton, R.; Ren, T.
  • An improved model for predicting soil thermal conductivity from water content at room temperature
    Lu, S.; Ren, T.; Gong, Y.; Horton, R.
  • Using late time data improves the heat–pulse method for estimating soil thermal properties with the pulsed infinite line source theory
    Lu, Y. L.; Wang, Y. J.; Ren, T.
  • An empirical model for estimating soil thermal conductivity from texture, water content, and bulk density
    Lu, Y. L.; Lu, S.; Horton, R.; Ren, T.
  • Soil surface heat flux: Some general questions and comments on measurements
    Mayocchi, C. L.; Bristow, K. L.
  • Dynamics of soil hydraulic properties during fallow as affected by tillage
    Moret, D.; Arrúe, J. L.
  • A new perspective on soil thermal properties
    Ochsner, T. E.; Horton, R.; Ren, T.
  • Field tests of the soil heat flux plate method and some alternatives
    Ochsner, T. E.; Sauer, T. J.; Horton, R.
  • Soil heat capacity and heat storage measurements in energy balance studies
    Ochsner, T. E.; Sauer, T. J.; Horton, R.
  • Field evaluation and improvement of the plate method for measuring soil heat flux density
    Peng, X.; Heitman, J.; Horton, R.; Ren, T.
  • The effect of soil thermal conductivity parameterization on surface energy fluxes and temperature
    Peters-Lidard, C. D.; Blackburn, E.; Liang, X.; Wood, E. F.
  • Development of thermo–time domain reflectometry for vadose zone measurements
    Ren, T.; Ochsner, T. E.; Horton, R.
  • Temporal dynamics of soil hydraulic properties and the water-conducting porosity under different tillage
    Schwen, A.; Bodner, G.; Scholl, P.; Buchan, G. D.; Loiskandl, W.
  • Electromagnetic determination of soil water content: Measurements in coaxial transmission lines
    Topp, G. C.; Davis, J. L.; Annan, A. P.
  • Spatio-temporal surface soil heat flux estimates from satellite data; Results for the AMMA experiment at the Fakara (Niger) supersite
    Verhoef, A.; Ottlé, C.; Cappelaere, B.; Murray, T.; Saux-Picart, S.; Zribi, M.; Ramier, D.
  • A novel approach for the estimation of soil ground heat flux
    Wang, Z. H.; Bou-Zeid, E.
  • Rapid numerical estimation of soil thermal properties for a broad class of heat-pulse emitter geometries
    Welch, S. M.; Kluitenberg, G. J.; Bristow, K. L.
  • Measuring near-surface soil thermal properties with the heat-pulse method: Correction of ambient temperature and soil–air interface effects
    Zhang, X.; Heitman, J.; Horton, R.; Ren, T.