A study on the partition of net radiation into heat fluxes on a dry asphalt surface

Variation of the energy budget components of a dry asphalt surface over an annual cycle is discussed based on the analysis of data collected from a micrometeorological road station near Vienna, in Austria. Net radiation (RN) and ground heat flux (G) are directly measured. Sensible heat flux (H) for dry surface conditions is estimated as a residual of the surface energy balance. Throughout the year, ground heat flux is found to be of larger magnitude than that of the sensible heat flux. The partitioning of net radiation into ground and sensible heat fluxes are studied. Variation of G (and H) with RN showed hysteresis loop behaviour with anti-clockwise cycle (clockwise for H) during cooler periods and clockwise cycle (anti-clockwise for H) during warm periods. The coefficients of time-dependent Camuffo and Bernadi formulations relating the net radiation with the heat fluxes are estimated for different periods of the year.