Road Weather Management Program
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Best Practices for Road Weather Management Version 2.0

Title:

The Applicability of Similarity Theory to a Road Surface

Abstract:

The existing models for predicting road surface temperature are often based on surface energy balance which includes contributions from sensible and latent heat exchanges between the atmosphere and road surface. The similarity theory is usually applied to compute the atmospheric turbulent heat fluxes. However, the theory only applies in horizontally homogeneous siturations, which is certainly not the case for road conditions. An investigation is carried out to see how much measured profiles of mean wind and temperature from a road meteorological station deviate from the profiles given by similarity theory. The difference between the data and the therory is revealed by comparing the observed gradients with the theoretical ones. The sign of the vertical gradients of all data and the relationships between two vertical gradients at 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 is discussed within the context of the possible existence of an internal boundary layer. Moreover, detailed temperature profiles were measured to study the development of temperatures in the first 2.5 meters. The results show that the sign of the temperature gradient reverses in a layer between 0.8 and 1.4 meters at that a large change in temperature occurs in this layer; these effects were probably caused by local advection.

Source(s):

Meteorological Applications of the Royal Meteorological Society Vol. 6 (United Kingdom), University of Göteborg, Laboratory of Climatology (Sweden). For an electronic copy of this resource, please direct your request to WeatherFeedback@dot.gov.

Date: 1999

Author:

Chen, Gustavsson, Bogren

Keywords:


Pavement temperature
Wind
Air temperature

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