Dual-Doppler Lidar Measurements for Improving Dispersion Models

Collier, C. G.; Davies, F.; Bozier, K. E.; Holt, A.R.; Middleton, D. R.; Pearson, Guy N.; Siemen, Stephan; Willetts, Dave V.; Upton, Graham; Young, Rob I.

doi:10.1175/bams-86-6-825

Cited by 70 publications

(58 citation statements)

References 25 publications

(23 reference statements)

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“…In order to derive the twodimensional (2-D) or three-dimensional (3-D) wind velocity the use of suitable measurement strategies and/or velocity retrieval algorithms is required. The 2-D and 3-D wind measurements from Doppler lidars are useful in various fields of study such as boundary layer meteorology (Fernando et al, 2015;Vanderwende et al, 2015), air quality (Barlow et al, 2011;Collier et al, 2005), wind energy research (Banta et al, 2015;Käsler et al, 2010;Mikkelsen, 2014;Newsom et al, 2015) and others. The simplest techniques to derive a profile of wind speed and direction using a single-Doppler lidar are the velocity azimuth display (VAD) technique (Browning and Wexler, 1968) and the Doppler beam swinging (DBS) technique (Strauch et al, 1984).…”

Section: Introductionmentioning

confidence: 99%

Evaluation of single and multiple Doppler lidar techniques to measure complex flow during the XPIA field campaign

et al. 2017

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Abstract. Accurate three-dimensional information of wind flow fields can be an important tool in not only visualizing complex flow but also understanding the underlying physical processes and improving flow modeling. However, a thorough analysis of the measurement uncertainties is required to properly interpret results. The XPIA (eXperimental Planetary boundary layer Instrumentation Assessment) field campaign conducted at the Boulder Atmospheric Observatory (BAO) in Erie, CO, from 2 March to 31 May 2015 brought together a large suite of in situ and remote sensing measurement platforms to evaluate complex flow measurement strategies.In this paper, measurement uncertainties for different single and multi-Doppler strategies using simple scan geometries (conical, vertical plane and staring) are investigated. The tradeoffs (such as time-space resolution vs. spatial coverage) among the different measurement techniques are evaluated using co-located measurements made near the BAO tower. Sensitivity of the single-/multi-Doppler measurement uncertainties to averaging period are investigated using the sonic anemometers installed on the BAO tower as the standard reference. Finally, the radiometer measurements are used to partition the measurement periods as a function of atmospheric stability to determine their effect on measurement uncertainty.It was found that with an increase in spatial coverage and measurement complexity, the uncertainty in the wind measurement also increased. For multi-Doppler techniques, the increase in uncertainty for temporally uncoordinated measurements is possibly due to requiring additional assumptions of stationarity along with horizontal homogeneity and less representative line-of-sight velocity statistics. It was also found that wind speed measurement uncertainty was lower during stable conditions compared to unstable conditions.

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Section: Introductionmentioning

confidence: 99%

Evaluation of single and multiple Doppler lidar techniques to measure complex flow during the XPIA field campaign

et al. 2017

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“…The depth of this layer, h, is a key variable in many applications such as air-pollution prediction and weather forecasting (Beyrich 1997). In environmental applications, h is one of the variables that defines the volume of air within which the pollution is mixed (Collier et al 2005). Therefore, accurate specification of h is essential in numerical modelling of air quality, including pollutant transport, dispersion and removal.…”

Section: Introductionmentioning

confidence: 99%

Determining Boundary-Layer Height from Aircraft Measurements

Dai

Wang

Kalogiros

et al. 2014

Boundary-Layer Meteorol

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The height of the atmospheric boundary layer (ABL) is an important variable in both observational studies and model simulations. The most commonly used measurement for obtaining ABL height is a rawinsonde profile. Mesoscale or regional scale models use a bulk Richardson number based on profiles of the forecast variables. Here we evaluate the limitations of several frequently-used approaches for defining ABL height from a single profile, and identify the optimal threshold value for each method if profiles are the only available measurements. Aircraft measurements from five field projects are used, representing a variety of ABL conditions including stable, convective, and cloud-topped boundary layers over different underlying surfaces. ABL heights detected from these methods were validated against the 'true' value determined from aircraft soundings, where ABL height is defined as the top of the layer with significant turbulence. A detection rate was defined to denote how often the ABL height was correctly diagnosed with a particular method. The results suggest that the temperature gradient method provides the most reasonable estimates, although the detection rate and suitable detection criteria vary for different types of ABL. The Richardson number method, on the other hand, is in most cases inadequate or inferior to the other methods that were tried. The optimal range of the detection criteria is given for all ABL types examined in this study.

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“…, 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%

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

et al. 2011

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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.

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Dual-Doppler Lidar Measurements for Improving Dispersion Models

Cited by 70 publications

References 25 publications

Evaluation of single and multiple Doppler lidar techniques to measure complex flow during the XPIA field campaign

Evaluation of single and multiple Doppler lidar techniques to measure complex flow during the XPIA field campaign

Determining Boundary-Layer Height from Aircraft Measurements

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

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