Abstract
The bulk transfer method combined with the heat balance equation of the surface requires the bulk transfer coefficient for sensible heat flux CHU and the surface moisture availability β (evapotranspiration efficiency) to evaluate the surface temperature Ts, sensible heat flux H and latent heat flux lE, respectively. This paper examines relations between these coefficients and various factors (soil moisture content, solar radiation).
Meteorological observations on a sorghum field in Tottori sand dune were carried out for 6-28 August, 1994. Significant results of the observations are the followings:
(1) The value of bulk transfer coefficient varied with the atmospheric stability.
(2) The value of β increased with increasing solar radiation, and tended to a constant value (β=0.35) when the solar radiation exceeded about 600Wm-2.
(3) The value of β increased according to the soil moisture content.
Observations of Ts, H and lE were compared with the simulations with the single source model (Kondo and Watanabe, 1992). This model simulates well the observed values of the daily mean of Ts, H and lE within an error of about±20Wm-2, ±20Wm-2 and ±1.1°C, respectively.
