Validity of the log-linear profile relationship over a rough terrain during stable conditions

Abstract

The applicability of the log-linear profile relationship over rough terrain to a height of 126 m is investigated. Simultaneous hourly averaged mean wind and temperature profiles measured at the Brookhaven meteorological tower during stable conditions are used in the analysis. The tower was surrounded by fairly homogeneous vegetation to a height of about 8 m. The results indicate that the log-linear profile relationship is valid at least for a height of 126 m for stabilities with Richardson numbers less than the critical value of 0.25. The mean value of α in ${{\partial u} \mathord{\left/ {\vphantom {{\partial u} {\partial z}}} \right. \kern-\nulldelimiterspace} {\partial z}} = \left( {{{u_ * } \mathord{\left/ {\vphantom {{u_ * } k}} \right. \kern-\nulldelimiterspace} k}} \right)\left( {1 + \alpha \left( {{z \mathord{\left/ {\vphantom {z L}} \right. \kern-\nulldelimiterspace} L}} \right)} \right)$ is found to be about 5.2 for these stabilities. The log-linear profile relation is found to be applicable for profiles observed beyond the critical stability; but the height of validity seems to decrease to about 100 m and the mean value of α is about 1.6.