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  • 1
    Electronic Resource
    Electronic Resource
    Radiative surface temperature and energy balance of a wheat canopy (1986)
    Springer
    Boundary layer meteorology 36 (1986), S. 1-17 
    Details
    ISSN: 1573-1472
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract For a stand of winter wheat, radiative canopy temperature measured with an infra-red radiometer was systematically related to a surface temperature derived from air temperature and wind speed profiles. Radiative temperature changed significantly with viewing angle and azimuth, but the influences of sun angle and ground cover were minimised by inclining the radiometer at 55 ° to the vertical and at right angles to the solar beam. At a standard viewing angle of 55 ° to the zenith, radiative canopy temperature was consistently 1 K cooler than the aerodynamic temperature. The algorithm used to describe this relation contains an effective canopy emissivity which decreases with viewing angle and an effective reflectivity. The observations establish a basis for incorporating canopy surface temperature into formulae for estimating the sensible heat loss from vegetation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00117455
    Library Location Call Number Volume/Issue/Year Availability
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    Paper (German National Licenses)
    Fulltext
  • 2
    Electronic Resource
    Electronic Resource
    Radiative surface temperature and energy balance of a wheat canopy (1986)
    Springer
    Boundary layer meteorology 36 (1986), S. 107-116 
    Details
    ISSN: 1573-1472
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The sensible heat loss from a stand of winter wheat was calculated from radiometric measurements of crop surface temperature, measurements of air temperature, and an atmospheric resistance to momentum transfer; corresponding latent heat flux was obtained through the energy balance equation. These estimates of sensible and latent heat were compared with fluxes from the Bowen Ratio method. When radiative temperature was derived using a measured canopy emissivity of 0.98, calculations of sensible heat flux were systematically 50–100 W m-2 less than Bowen Ratio values. The two techniques agreed more closely when an apparent emissivity of 0.96 was used with an apparent reflectivity of 0.03. The mean difference between the estimates of latent heat flux was then -16 ± 32 W m-2. The surface temperature method showed less systematic error in comparison with the Bowen Ratio values than did estimates using the aerodynamic method.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00117462
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
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