Soil Surface Roughness Effects on Radiation Reflectance and Soil Heat Flux1
- K. N. Potter,
- R. Horton and
- R. M. Cruse2
Soil surface roughness provides a mechanism to alter soil reflectance and the surface energy balance. A field study was conducted to determine the effect of surface roughness on energy absorption and energy partitioning at the soil surface. A range of surface roughness conditions was created by varying the intensity of secondary tillage after moldboard plowing. Parameters measured included spectral reflectance, net radiation, soil temperature, and soil heat flux. Reflectance of solar radiation decreased with increasing surface roughness, with the greatest differences occurring among radiation wavelengths of 850 and 1350 nm. Reflectance was similar between 400 and 850 nm. Reflectance from a visibly dry surface was increased up to 25% in some wavelengths 5 d after a 47-mm rainfall event, possibly because of decreased surface roughness. Although net radiation increased with increased surface roughness, soil heat flux at 0.01-m was similar for all roughness conditions. This indicates that the latent and/or sensible heat flux was increased by increasing surface roughness. Theoretical considerations indicate that increasing surface roughness results in greater transport of energy from the soil surface to the atmosphere. Relationships between the change in net radiation due to surface roughness and the partitioning of net radiation among the surface energy balance components are developed and presented graphically.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
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