Parametrizing Horizontally-Averaged Wind and Temperature Profiles in the Urban Roughness Sublayer

• Published in: Boundary-layer meteorology Vol. 173; no. 3; pp. 321 - 348
• Main Authors: Theeuwes, Natalie E., Ronda, Reinder J., Harman, Ian N., Christen, Andreas, Grimmond, C. Sue B.
• Format: Journal Article
• Language: English
• Published: Dordrecht Springer Netherlands 01.12.2019; Springer; Springer Nature B.V
• Subjects: Air quality; Analysis; Anisotropy; Atmospheric Protection/Air Quality Control/Air Pollution; Atmospheric Sciences; Boundary conditions; Corrections; Earth and Environmental Science; Earth Sciences; Formulations; Heat flux; Heat sinks; Heat transfer; Meteorological satellites; Meteorology; Momentum; Numerical weather forecasting; Parameterization; Plant cover; Prediction models; Profiles; Research Article; Roughness; Roughness length; Similarity theory; Surface boundary layer; Temperature effects; Temperature profile; Temperature profiles; Urban areas; Urban environments; Vertical profiles; Weather; Weather forecasting; Wind; Wind speed; Roughness sublayer; Wind profile; Temperature profile; Urban canopy
• ISSN: 0006-8314; 1573-1472
• DOI: 10.1007/s10546-019-00472-1

Tower-based measurements from within and above the urban canopy in two cities are used to evaluate several existing approaches that parametrize the vertical profiles of wind speed and temperature within the urban roughness sublayer (RSL). It is shown that current use of Monin–Obukhov similarity theory (MOST) in numerical weather prediction models can be improved upon by using RSL corrections when modelling the vertical profiles of wind speed and friction velocity in the urban RSL using MOST. Using anisotropic building morphological information improves the agreement between observed and parametrized profiles of wind speed and momentum fluxes for selected methods. The largest improvement is found when using dynamically-varying aerodynamic roughness length and displacement height. Adding a RSL correction to MOST, however, does not improve the parametrization of the vertical profiles of temperature and heat fluxes. This is expected since sources and sinks of heat are assumed uniformly distributed through a simple flux boundary condition in all RSL formulations, yet are highly patchy and anisotropic in a real urban context. Our results can be used to inform the choice of surface-layer representations for air quality, dispersion, and numerical weather prediction applications in the urban environment.