Estimation of sensible heat flux by a hybrid method of temperature profile and light-beam deflection

Abstract

A new method of sensible heat flux estimation by a hybrid use of temperature profile and light-beam deflection is proposed and tested over an asphalt pavement on fine days.A helium-neon gas laser with wavelength 0.6328 pm was used as a light-beam source. Temperature gradient near the surface was measured by the deflection of a light-beam propagated nearly horizontally at a distance of 25 m. Measurement of the air temperature profile in the upper part of the surface layer was made by means of a copper-constantan thermocouple thermometer. The sensible heat flux was estimated from the temperature profile using profile-flux relationships.The surface temperature of the asphalt pavement rose to as high as 63 "C in the daytime and never decreased below the air temperature even in the morning in summer. The maximum value of heat flux obtained from this observation attained 365 W m-z, which was about 48% of incoming solar radiation.