Urban air pollution modelling and measurements of boundary layer height

Davies, F.; Middleton, D. R.; Bozier, K. E.

doi:10.1016/j.atmosenv.2007.01.015

Cited by 59 publications

(37 citation statements)

References 22 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…In urban areas, various methods have been used, including sodar (Spanton and Williams, 1992, London); Emeis and Turk, 2004, Hannover), lidar (He et al, 2006, Beijing;Davies et al, 2007, London;Chen et al, 2001, Tsukuba) or a combination of methods including Radio Acoustic Sounding System (RASS), ceilometers, wind profiles and radar (Dupont et al, 1999, Paris;Angevine et al, 2003, Nashville;Emeis et al, 2004, Hannover). Generally it has been found that the UBL is deeper than the surrounding rural boundary layer (Angevine et al, 2003;Davies et al, 2007;Dupont et al, 1999).…”

Section: Introductionmentioning

confidence: 99%

“…, Emeis et al (2007) and Barlow et al (2008) used acoustic remote sensing to derive wind profiles and noted the sensitivity of the profile to underlying roughness which can be highly heterogeneous in urban areas. Use of dual Doppler lidars (Collier et al, 2005;Newsom et al, 2005;Davies et al, 2007) can improve the accuracy in derived wind profiles and provide dense networks of "virtual towers" (Calhoun et al, 2006, Oklahoma City), especially useful if the urban windfield is complex due to e.g. tall buildings or changing landuse.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Boundary layer dynamics over London, UK, as observed using Doppler lidar during REPARTEE-II

et al. 2011

Self Cite

View full text Add to dashboard Cite

Abstract. Urban boundary layers (UBLs) can be highly complex due to the heterogeneous roughness and heating of the surface, particularly at night. Due to a general lack of observations, it is not clear whether canonical models of boundary layer mixing are appropriate in modelling air quality in urban areas. This paper reports Doppler lidar observations of turbulence profiles in the centre of London, UK, as part of the second REPARTEE campaign in autumn 2007. Lidar-measured standard deviation of vertical velocity averaged over 30 min intervals generally compared well with in situ sonic anemometer measurements at 190 m on the BT telecommunications Tower. During calm, nocturnal periods, the lidar underestimated turbulent mixing due mainly to limited sampling rate. Mixing height derived from the turbulence, and aerosol layer height from the backscatter profiles, showed similar diurnal cycles ranging from c. 300 to 800 m, increasing to c. 200 to 850 m under clear skies. The aerosol layer height was sometimes significantly different to the mixing height, particularly at night under clear skies. For convective and neutral cases, the scaled turbulence profiles resembled canonical results; this was less clear for the stable case. Lidar observations clearly showed enhanced mixing beneath stratocumulus clouds reaching down on occasion to approximately half daytime boundary layer depth. OnCorrespondence to: J. F. Barlow (j.f.barlow@reading.ac.uk) one occasion the nocturnal turbulent structure was consistent with a nocturnal jet, suggesting a stable layer. Given the general agreement between observations and canonical turbulence profiles, mixing timescales were calculated for passive scalars released at street level to reach the BT Tower using existing models of turbulent mixing. It was estimated to take c. 10 min to diffuse up to 190 m, rising to between 20 and 50 min at night, depending on stability. Determination of mixing timescales is important when comparing to physicochemical processes acting on pollutant species measured simultaneously at both the ground and at the BT Tower during the campaign. From the 3 week autumnal data-set there is evidence for occasional stable layers in central London, effectively decoupling surface emissions from air aloft.

show abstract

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Boundary layer dynamics over London, UK, as observed using Doppler lidar during REPARTEE-II

et al. 2011

Self Cite

View full text Add to dashboard Cite

show abstract

“…These experiments occurred mainly over forests, canyons, suburban areas, and over the ocean. However, much more attention has been paid to urban areas in recent years; for example in Hannover (Emeis et al 2004), Beijing (He et al 2006), London (Davies et al 2007), and Houston (Haman et al 2012). However, appropriate algorithms to derive the PBL depths are required (Emeis et al 2008).…”

Section: Introductionmentioning

confidence: 99%

Estimate of Boundary-Layer Depth Over Beijing, China, Using Doppler Lidar Data During SURF-2015

Huang

Gao

Miao

et al. 2016

Boundary-Layer Meteorol

View full text Add to dashboard Cite

Planetary boundary-layer (PBL) structure was investigated using observations from a Doppler lidar and the 325-m Institute of Atmospheric Physics (IAP) meteorological tower in the centre of Beijing during the summer 2015 Study of Urban-impacts on Rainfall and Fog/haze (SURF-2015) field campaign. Using six fair-weather days of lidar and tower data under clear to cloudy skies, we evaluate the ability of the Doppler lidar to probe the urban boundary-layer structure, and then propose a composite method for estimating the diurnal cycle of the PBL depth using the Doppler lidar. For the convective boundary layer (CBL), a threshold method using vertical velocity variance (σ 2 w > 0.1 m 2 s −2 ) is used, since it provides more reliable CBL depths than a conventional maximum wind-shear method. The nocturnal boundary-layer (NBL) depth is defined as the height at which σ 2 w decreases to 10 % of its near-surface maximum minus a background variance. The PBL depths determined by combining these methods have average values ranging from ≈270 to ≈1500 m for the six days, with the greatest maximum depths associated with clear skies. Release of stored and anthropogenic heat contributes to the maintenance of turbulence until late evening, keeping the NBL near-neutral and deeper at night than would be expected over a natural surface. The NBL typically becomes more shallow with time, but grows in the presence of low-level nocturnal jets. While current results are promising, data over a broader range of conditions are needed to fully develop our PBL-depth algorithms.

show abstract

“…In order to develop effective mitigation strategies in these urban environments, it is important to understand all processes leading to the formation of an UHI and significant related processes such as air quality, cooling energy demand and human comfort. Recently, there has been a growing interest in quantitative research in boundary layer dynamics and air pollution processes [Davies et al, 2007]. Piringer and Joffre [2005] comment that the incorporation of urbantype surface forcing is important for a correct modeling of urban pollution dispersion.…”

Section: Introductionmentioning

confidence: 99%

Modeling the energy balance in Marseille: Sensitivity to roughness length parameterizations and thermal admittance

Demuzere¹,

Ridder²,

Lipzig³

2008

J. Geophys. Res.

View full text Add to dashboard Cite

[1] During the ESCOMPTE campaign (Experience sur Site pour COntraindre les Modeles de Pollution atmospherique et de Transport d'Emissions), a 4-day intensive observation period was selected to evaluate the Advanced Regional Prediction System (ARPS), a nonhydrostatic meteorological mesoscale model that was optimized with a parameterization for thermal roughness length to better represent urban surfaces. The evaluation shows that the ARPS model is able to correctly reproduce temperature, wind speed, and direction for one urban and two rural measurements stations. Furthermore, simulated heat fluxes show good agreement compared to the observations, although simulated sensible heat fluxes were initially too low for the urban stations. In order to improve the latter, different roughness length parameterization schemes were tested, combined with various thermal admittance values. This sensitivity study showed that the Zilitinkevich scheme combined with and intermediate value of thermal admittance performs best.

show abstract

Urban air pollution modelling and measurements of boundary layer height

Cited by 59 publications

References 22 publications

Boundary layer dynamics over London, UK, as observed using Doppler lidar during REPARTEE-II

Boundary layer dynamics over London, UK, as observed using Doppler lidar during REPARTEE-II

Estimate of Boundary-Layer Depth Over Beijing, China, Using Doppler Lidar Data During SURF-2015

Modeling the energy balance in Marseille: Sensitivity to roughness length parameterizations and thermal admittance

Contact Info

Product

Resources

About