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

Natalie E. Theeuwes*, Reinder J. Ronda, Ian N. Harman, Andreas Christen, Sue B. Grimmond

*Corresponding author for this work

Research output: Contribution to journalArticleAcademicpeer-review

Abstract

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.

Original languageEnglish
Pages (from-to)321-348
Number of pages28
JournalBoundary-Layer Meteorology
Volume173
Issue number3
DOIs
Publication statusPublished - Dec 2019

Fingerprint

wind profile
temperature profile
roughness
vertical profile
wind velocity
weather
prediction
aerodynamics
heat flux
surface layer
momentum
air quality
boundary condition
friction
temperature
canopy
modeling

Keywords

  • Roughness sublayer
  • Temperature profile
  • Urban canopy
  • Wind profile

Cite this

Theeuwes, Natalie E. ; Ronda, Reinder J. ; Harman, Ian N. ; Christen, Andreas ; Grimmond, Sue B. / Parametrizing Horizontally-Averaged Wind and Temperature Profiles in the Urban Roughness Sublayer. In: Boundary-Layer Meteorology. 2019 ; Vol. 173, No. 3. pp. 321-348.
@article{fff33f9522bb460aa9f64d0a53bf2f9a,
title = "Parametrizing Horizontally-Averaged Wind and Temperature Profiles in the Urban Roughness Sublayer",
abstract = "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.",
keywords = "Roughness sublayer, Temperature profile, Urban canopy, Wind profile",
author = "Theeuwes, {Natalie E.} and Ronda, {Reinder J.} and Harman, {Ian N.} and Andreas Christen and Grimmond, {Sue B.}",
year = "2019",
month = "12",
doi = "10.1007/s10546-019-00472-1",
language = "English",
volume = "173",
pages = "321--348",
journal = "Boundary-Layer Meteorology",
issn = "0006-8314",
publisher = "Springer Verlag",
number = "3",

}

Parametrizing Horizontally-Averaged Wind and Temperature Profiles in the Urban Roughness Sublayer. / Theeuwes, Natalie E.; Ronda, Reinder J.; Harman, Ian N.; Christen, Andreas; Grimmond, Sue B.

In: Boundary-Layer Meteorology, Vol. 173, No. 3, 12.2019, p. 321-348.

Research output: Contribution to journalArticleAcademicpeer-review

TY - JOUR

T1 - Parametrizing Horizontally-Averaged Wind and Temperature Profiles in the Urban Roughness Sublayer

AU - Theeuwes, Natalie E.

AU - Ronda, Reinder J.

AU - Harman, Ian N.

AU - Christen, Andreas

AU - Grimmond, Sue B.

PY - 2019/12

Y1 - 2019/12

N2 - 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.

AB - 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.

KW - Roughness sublayer

KW - Temperature profile

KW - Urban canopy

KW - Wind profile

U2 - 10.1007/s10546-019-00472-1

DO - 10.1007/s10546-019-00472-1

M3 - Article

VL - 173

SP - 321

EP - 348

JO - Boundary-Layer Meteorology

JF - Boundary-Layer Meteorology

SN - 0006-8314

IS - 3

ER -