Estimation of sensible heat flux from remotely sensed canopy temperatures

Abstract

Temperatures of tallgrass prairie vegetation were measured with infrared thermometers (IRT) at different view zenith and azimuth angles. The optimum IRT view zenith angle for estimating sensible heat fluxes (H) was determined by comparing H estimated with eddy correlation and/or Bowen ratio techniques to H calculated by a method suggested by Hatfield et al. (1984). For wind speeds of 5 m s−1 or greater, H estimated with surface temperatures measured at a 0° or 20° view zenith angle gave the best agreement, but for wind speeds of less than 4 m s−1 the best estimate of H was made with surface temperatures measured at a 40° or 60° view zenith angle.

Remote sensing in hydrology

“…(13) are not uniquely defined by surface roughness parameters. In addition to experimental evidence (e.g., [124,125]), Kustas et al [58] using a complex soil-vegetation-atmosphere-transfer (SVAT) model (Cupid [79]) have shown the lack of a unique relationship between T R ðhÞ and the ''aerodynamic'' surface temperature, T 0 .…”

Remote Sensing Research in Hydrometeorology

“…Furthermore, as evidence from many previous studies, both the resistances in Equation 9 and consequently the parameterization in Equation 11 are not uniquely defined by surface roughness parameters. In addition to experimental evidence (e.g., Vining and Blad, 1992;Verhoef et al, 1997), Kustas et al (2003), using a complex soil-vegetation-atmosphere-transfer (SVAT) model (Cupid; Norman and Campbell, 1983), have shown the lack of a unique relationship between T R (u) and the so-called "aerodynamic" surface temperature, T O , (T O is the temperature satisfying Equation 9 with traditional expressions for the resistances; see Norman and Becker (1995)). An alternative approach recently proposed considers the soil and vegetation contribution to the total or composite heat fluxes and soil and vegetation temperatures to the radiometric temperature measurements in a so-called "Two-Source" Modeling (TSM) scheme .…”

Relations between Aerodynamic Parameters of Heat Transfer and Thermal-Infrared Thermometry in the Bulk Surface Formulation

“…2. The sensible heat flux over a vegetation surface is overestimated under unstable conditions in the daytime, when a TIR surface temperature measured in the near nadir angle is substituted for the bulk formulation (Vining and Blad 1992;Matsushima and Kondo 1997). 3.…”