Use of airborne lidar to determine aerosol sources and movement in the Lower Fraser Valley (LFV), BC

Hoff, R.; Harwood, Michael G.; Sheppard, Adam; Froude, F.; Martin, J.B.; Strapp, W.

doi:10.1016/s1352-2310(96)00302-0

Cited by 35 publications

(14 citation statements)

References 16 publications

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“…This could indicate that the horizontal scale of the depression in CBL height varies and is not necessarily as confined to the mountain base as is seen in the example above. Although only one example of the CBL height depression near a mountain base is presented, several other lidar cross sections on other days during Pacific'93 show a similar feature (Hoff et al 1997). …”

Section: Observations Of a "Cbl Height Depression"mentioning

confidence: 91%

“…Airborne lidar data have proven very useful in field campaigns to examine the spatial variability of the CBL height (e.g., Hoff et al 1997;Nyeki et al 2000). As part of Pacific'93, a 1.064-m downward-looking Nd-Yag lidar was flown on an aircraft (Convair 580) at approximately 4200 m MSL.…”

Section: Observations Of a "Cbl Height Depression"mentioning

confidence: 99%

“…The horizontal and vertical resolutions of the lidar measurements were approximately 200 and 10 m, respectively. Lidar measurements are described in detail by Hoff et al (1997). Figures 2a and 2b show airborne lidar data in the flight tracks T1 and L7, respectively, on 4 August 1993.…”

Section: Observations Of a "Cbl Height Depression"mentioning

confidence: 99%

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Observational and Numerical Evidence of Depressed Convective Boundary Layer Heights near a Mountain Base

Wekker

2008

Journal of Applied Meteorology and Climatology

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Recent field and numerical studies show evidence of the existence of a convective boundary layer height depression near a mountain base. This depression can have implications for air pollutant transport and concentrations in complex terrain. To investigate the mechanisms underlying this phenomenon, idealized simulations with a mesoscale numerical model are performed and combined with available observations. The idealized simulations with a single mountain ridge of various dimensions suggest that the depression evolves in time, is most pronounced in the late afternoon, and becomes larger as slope steepness increases. Observations and modeling results show that the atmosphere is heated more intensely near the mountain base than far away from the mountain base, not only inside the boundary layer but also above. The enhanced heating aloft affects boundary layer growth near the mountain base and is associated with the boundary layer height depression. An analysis of the different terms in the temperature tendency equation indicates that vertical and horizontal advection of warm air, associated with the thermally driven circulation along the mountain slope, play a role in this enhanced heating aloft.

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Section: Observations Of a "Cbl Height Depression"mentioning

confidence: 91%

Section: Observations Of a "Cbl Height Depression"mentioning

confidence: 99%

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Observational and Numerical Evidence of Depressed Convective Boundary Layer Heights near a Mountain Base

Wekker

2008

Journal of Applied Meteorology and Climatology

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“…A widely used approach is based on the computation of the derivative of the elastic lidar backscatter signal (Russell et al, 1974;Menut et al, 1999;Bösenberg and Linné, 2002;Frioud et al, 2003;Matthias et al, 2004;Pal et al, 2010). An estimate of the PBL height can also be obtained from the elastic lidar signal variance (Hooper and Eloranta, 1986;Menut et al, 1999) or considering threshold signal levels (Melfi et al, 1985;Hayden et al, 1997;Steyn et al, 1999;Hoff et al, 1997;Hägeli et al, 2000;Cohn and Angevine, 2000;Davis et al, 2000;Brooks, 2003).…”

Section: Summa Et Al: Estimate Of Planetary Boundary Layer Heightmentioning

confidence: 99%

Characterization of the planetary boundary layer height and structure by Raman lidar: comparison of different approaches

et al. 2013

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Abstract.The planetary boundary layer (PBL) includes the portion of the atmosphere which is directly influenced by the presence of the earth's surface. Aerosol particles trapped within the PBL can be used as tracers to study the boundarylayer vertical structure and time variability. As a result of this, elastic backscatter signals collected by lidar systems can be used to determine the height and the internal structure of the PBL.The present analysis considers three different methods to estimate the PBL height. The first method is based on the determination of the first-order derivative of the logarithm of the range-corrected elastic lidar signals. Estimates of the PBL height for specific case studies obtained through this approach are compared with simultaneous estimates from the potential temperature profiles measured by radiosondes launched simultaneously to lidar operation. Additional estimates of the boundary layer height are based on the determination of the first-order derivative of the range-corrected rotational Raman lidar signals. This latter approach results to be successfully applicable also in the afternoon-evening decaying phase of the PBL, when the effectiveness of the approach based on the elastic lidar signals may be compromised or altered by the presence of the residual layer. Results from these different approaches are compared and discussed in the paper, with a specific focus on selected case studies collected by the University of Basilicata Raman lidar system BASIL during the Convective and Orographically-induced Precipitation Study (COPS).

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“…Virtually all ambient CO (~97%) and NO x in the LFV can be attributed to motor vehicle emissions, and as the transportation sector is also the major source of particulate matter in the LFV, 15,17 correlations between these pollutants provide a valuable means by which to assess the relative apportionment of vehicular versus other sources of PM 10 . During winter at Richmond-T17, PM 10 is well correlated with both CO (r = 0.7) and NO x (r = 0.78) and is consistent with a significant transportation sector input to PM 10 concentrations.…”

Section: Spatial Variations In Pm 10 Concentrationsmentioning

confidence: 99%

PM₁₀ Levels in the Lower Fraser Valley, British Columbia, Canada: An Overview of Spatiotemporal Variations and Meteorological Controls

McKendry

2000

Journal of the Air & Waste Management Association

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Three years of hourly averaged PM 10 (particulate matter less than 10 µm in diameter) tapered element oscillating microbalance (TEOM) data from 10 sites in the large coastal valley incorporating Greater Vancouver were used to investigate the spatiotemporal dimensions and air pollution meteorology of particulate pollution. During the period studied, the provincial "acceptable" objective daily concentration of 50 µg m -3 was exceeded at 7 of the 10 sites. The highest annual, seasonal, and maximum hourly concentrations were recorded at Abbotsford in the central valley. Mean seasonal PM 10 concentrations were highest in the wintertime in the western Lower Fraser Valley (LFV) and in the summertime at the central and eastern valley locations. Within the network, interstation correlations of daily average concentrations exceed 0.8 at IMPLICATIONS An extensive database of continuous PM 10 measurements from 10 TEOM monitoring stations provides a rare opportunity to explore spatial and temporal variations as well as meteorological controls on particulate matter concentrations in a traffic-dominated setting. Although the exact magnitude of the effect of volatilization of fine particles in continuous TEOM instruments in the LFV data is as yet unknown, it is possible that the effect varies both spatially and temporally (e.g., due to the production and transport of secondary particles during summer). Within the network, strong local effects are identified that suggest a denser network is required to adequately resolve spatial variations. Nocturnal "spikes" in concentrations apparent at two urban sites illustrate the value of continuous versus daily monitoring, while a mix of anthropogenic and natural sources implies an urgent need for PM 2.5 monitoring (this would be advantageous in epidemiological studies). Identification of particular weather patterns associated with elevated concentrations holds the promise of improved PM 10 forecasting and suggests that care should be taken to accommodate meteorological variability in trend analyses.interstation distances less than 20 km and decrease thereafter. For daily maximum concentrations (hourly), interstation correlations decrease sharply with distance. Meteorological conditions responsible for elevated particulate concentrations in the LFV are associated with (1) short periods (1-to 3-hr duration) of reduced dispersion during summer nights at sites close to primary sources, (2) summer anticyclonic conditions when photochemical pollutant concentrations build up across the entire valley, and (3) occasional wintertime "gap wind" events in the eastern valley.

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Use of airborne lidar to determine aerosol sources and movement in the Lower Fraser Valley (LFV), BC

Cited by 35 publications

References 16 publications

Observational and Numerical Evidence of Depressed Convective Boundary Layer Heights near a Mountain Base

Observational and Numerical Evidence of Depressed Convective Boundary Layer Heights near a Mountain Base

Characterization of the planetary boundary layer height and structure by Raman lidar: comparison of different approaches

PM₁₀ Levels in the Lower Fraser Valley, British Columbia, Canada: An Overview of Spatiotemporal Variations and Meteorological Controls

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Use of airborne lidar to determine aerosol sources and movement in the Lower Fraser Valley (LFV), BC

Cited by 35 publications

References 16 publications

Observational and Numerical Evidence of Depressed Convective Boundary Layer Heights near a Mountain Base

Observational and Numerical Evidence of Depressed Convective Boundary Layer Heights near a Mountain Base

Characterization of the planetary boundary layer height and structure by Raman lidar: comparison of different approaches

PM10 Levels in the Lower Fraser Valley, British Columbia, Canada: An Overview of Spatiotemporal Variations and Meteorological Controls

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PM₁₀ Levels in the Lower Fraser Valley, British Columbia, Canada: An Overview of Spatiotemporal Variations and Meteorological Controls