Quantification of Plume Opacity by Digital Photography

Du, Ke; Rood, Mark J.; Kim, Byung J.; Kemme, Michael R.; Franek, Bill; Mattison, Kevin

doi:10.1021/es061277n

Cited by 21 publications

(19 citation statements)

References 11 publications

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“…And the challenge to install contrasting backgrounds behind and next to the DDs as needed with DOM's contrast model (Du et al, 2007). The transmission model calculates the plume's opacity based on the radiance from the plume and the radiance from the plume's background.…”

Section: Calculation Of Opacitymentioning

confidence: 99%

“…Because the camera did not directly measure N t2 , the proportionality coefficient, K, is defined by N t2 = K × N × opacity (Du et al, 2007), and then the plume opacity could be determined by the transmission model as described by…”

Section: Calculation Of Opacitymentioning

confidence: 99%

“…The DOM software is provided by Mark J. Rood (doi:10.1021/es061277n; Du et al, 2007). The DD pictures and opacity data are available upon request from Zhaopeng Luan (luanzp2014@163.com).…”

Section: Data Availabilitymentioning

confidence: 99%

“…The digital optical method (DOM) was developed to measure opacities of plumes emitted from stationary point sources (Du et al, 2007(Du et al, , 2009). DOM uses a digital still camera and software for processing the digital pictures to determine plume opacity.…”

Section: Introductionmentioning

confidence: 99%

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Dust opacities inside the dust devil column in the Taklimakan Desert

et al. 2017

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Abstract. The distribution of dust aerosols in dust devils (DDs) is quantitatively characterized here based on a field observation. We applied the digital optical method (DOM) with digital still cameras to quantify the opacity of the DDs in the Taklimakan Desert, China. This study presents the following unique and important results: (1) the distinct horizontal distributions of opacity proved the existence of DDs' eye, similarly to the eye of tropical cyclone; (2) the opacity of the DDs decreases with increasing height; however, the dust aerosols do appear to settle out, and the relatively calm eye leads to a minimum in dust opacity at the eye; (3) the horizontal distribution of opacity is quasi-symmetric with a bimodal across the eye of the DDs, which could be resulted from the ambient air conditions; and (4) a new method is developed for characterizing the three-dimensional structure of DDs based on the observed two-dimensional opacity provided by DOM. This study not only proposes a highly reliable, low-cost and efficient methodology to capture the optical structure of DDs, but it could also provide the information on estimation of dust emissions driven by DDs.

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Section: Calculation Of Opacitymentioning

confidence: 99%

Section: Calculation Of Opacitymentioning

confidence: 99%

“…The DOM software is provided by Mark J. Rood (doi:10.1021/es061277n; Du et al, 2007). The DD pictures and opacity data are available upon request from Zhaopeng Luan (luanzp2014@163.com).…”

Section: Data Availabilitymentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Dust opacities inside the dust devil column in the Taklimakan Desert

et al. 2017

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“…Most recently, DOCS was tested using a range of commercially available cameras in lieu of a specific digital camera that was required to be used for the previous field campaigns (12). Another DSC-based method, digital optical method (DOM), was developed from light transfer principles to quantify plume opacity using commercial-off-the-shelf digital still cameras (13). Testing during daytime demonstrated that DOM provided results that are consistent with Method 9 requirements (14).…”

Section: Introductionmentioning

confidence: 99%

Evaluation of Digital Optical Method To Determine Plume Opacity during Nighttime

Du¹,

Rood²,

Kim³

et al. 2009

Environ. Sci. Technol.

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United States Environmental Protection Agency (USEPA) set opacity standards for visual emissions from industrial sources to protect ambient air quality. USEPA developed Method 9, which is a reference method to describe how plume opacity can be quantified by human observers during daytime conditions. However, it would be beneficial to determine plume opacity with digital still cameras (DSCs) to provide graphical records of the plume and its environment during visual emission evaluation and to be able to determine plume opacity with DSCs during nighttime conditions. Digital optical method (DOM) was developed to quantify plume opacity from photographs that were provided by a DSC during daytime. Past daytime field campaigns have demonstrated that DOM provided opacity readings that met Method 9 certification requirements. In this paper, the principles and methodology of DOM to quantify plume opacity during nighttime are described. Also, results are described from a nighttime field campaign that occurred at Springfield, IL. Opacity readings provided by DOM were compared with the opacity values obtained with the reference in-stack transmissometer of the smoke generator. The average opacity errors were 2.3-3.5% for contrast model of DOM for all levels of plume opacity. The average opacity errors were 2.0-7.6% for the transmission model of DOM for plumes with opacity 0-50%. These results are encouraging and indicate that DOM has the potential to quantify plume opacity during nighttime.

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Observational study of formation mechanism, vertical structure, and dust emission of dust devils over the Taklimakan Desert, China

et al. 2016

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A field observation of dust devils was conducted at Xiaotang over the Taklimakan Desert (TD), China, from 7 to 14 July 2014. The measurements of dust devil opacity with the digital optical method and the observed atmospheric boundary layer conditions were applied to investigate the dust devils' formation mechanism, vertical structure, and dust emissions. The critical conditions in the atmospheric boundary layer for dust devil formation were revealed with the land-air surface temperature difference of higher than 15°C, the enhanced momentum flux and sensible heat flux up to 0.54 kg m À1 s À2 and 327 W m À2 , respectively, the weak vertical wind shear with the low wind shear index α < 0.10, and the unstable stratification in the lower atmosphere. Based on observed dust opacities, it is identified that a typical dust devil was vertically structured with central updrafts and peripheral downdrafts of dust particles with the asymmetrically horizontal distribution of dust in a rotating dust column. The vertical flux of near-surface dust emissions was also estimated in a range from 5.4 × 10 À5 to 9.6 × 10 À5 kg m À2 s À1 for a typical dust devil event over TD.

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Quantification of Plume Opacity by Digital Photography

Cited by 21 publications

References 11 publications

Dust opacities inside the dust devil column in the Taklimakan Desert

Dust opacities inside the dust devil column in the Taklimakan Desert

Evaluation of Digital Optical Method To Determine Plume Opacity during Nighttime

Observational study of formation mechanism, vertical structure, and dust emission of dust devils over the Taklimakan Desert, China

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