The applicability of similarity theory surface

The existing models for predicting road surface temperature are often based on surface energy balance which includes contributions from sensible and l atent heat exchanges between the atmosphere and road surface. The similarit y theory is usually applied to compute the atmospheric turbulent heat fluxe s. However the theory only applies in horizontally homogeneous situations, which is certainly not the cdse for road conditions. An investigation is ca rried out to see how much measured profiles of mean wind and temperature fr om a road meteorological station deviate from the profiles given by similar ity theory. The difference between the data and the theory is revealed by c omparing the observed gradients with the theoretical ones. The sign of the vertical gradients of all data and the relationships between two vertical g radients dt different levels under near-neutral conditions are examined. It is found that the measured profiles are all systematically different from the theoretical ones. The deviation as discussed within the contest of the possible existence of an internal boundary layer. Moreover, detailed temper ature profiles were measured to study the development of temperatures in th e first 2.5 m. The results show that the sign of the temperature gradient r everses in a layer between 0.8 and 1.4 m anal that a large change in temper ature occurs in this layer; these effects were probably caused by local adv ection.