Across North America tracer experiment (ANATEX): Sampling and analysis

Draxler, Roland R.; Dietz, R.N.; Lagomarsino, R. J.; Start, G.E.

doi:10.1016/0960-1686(91)90208-o

Cited by 52 publications

(40 citation statements)

References 14 publications

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“…Their uncertainties increase substantially with time. 114,115 The TSA method used to identify source regions for SO 4 2Ϫ and trace elements in New York state assumed that local source contributions were independent of back trajectories (or prevailing wind directions). 50,116 This assumption contradicts assumptions of CPF and NPR, that is, local source contributions depend on wind patterns.…”

Section: Wind and Back Trajectory Analysismentioning

confidence: 99%

Source Apportionment: Findings from the U.S. Supersites Program

Watson

Chen

Chow

et al. 2008

Journal of the Air & Waste Management Association

222

132

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Receptor models are used to identify and quantify source contributions to particulate matter and volatile organic compounds based on measurements of many chemical components at receptor sites. These components are selected based on their consistent appearance in some source types and their absence in others. UNMIX, positive matrix factorization (PMF), and effective variance are different solutions to the chemical mass balance (CMB) receptor model equations and are implemented on available software. In their more general form, the CMB equations allow spatial, temporal, transport, and particle size profiles to be combined with chemical source profiles for improved source resolution. Although UNMIX and PMF do not use source profiles explicitly as input data, they still require measured profiles to justify their derived source factors. The U.S. Supersites Program provided advanced datasets to apply these CMB solutions in different urban areas. Still lacking are better characterization of source emissions, new methods to estimate profile changes between source and receptor, and systematic sensitivity tests of deviations from receptor model assumptions. INTRODUCTIONReceptor-oriented source apportionment models infer source contributions and atmospheric processes from air quality measurements. Receptor models complement, rather than replace, source-oriented dispersion and chemical transformation models that begin with source emission rates to estimate ambient concentrations. 1,2 Source and receptor models are mathematical representations of reality, requiring simplifying assumptions that create uncertainty. Applying both types of models to the same situation allows them to be improved when their results diverge and lends confidence to their results when they agree. 3

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Section: Wind and Back Trajectory Analysismentioning

confidence: 99%

Source Apportionment: Findings from the U.S. Supersites Program

Watson

Chen

Chow

et al. 2008

Journal of the Air & Waste Management Association

222

132

View full text Add to dashboard Cite

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“…In these experiments, the source terms were well-quantified and comprehensive measurements were made subsequently over an extended area (e.g. Draxler et al, 1991;Van Dop et al, 1998). With the known source terms, they provide a unique 30 opportunity to evaluate the STE methods.…”

Section: Introductionmentioning

confidence: 99%

Weak-constraint inverse modeling using HYSPLIT Lagrangian dispersion model and Cross Appalachian Tracer Experiment (CAPTEX) observations – Effect of including model uncertainties on source term estimation

Chai¹,

Stein²,

Ngan³

2018

Preprint

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Abstract.A HYSPLIT inverse system that is based on variational data assimilation and a Lagrangian dispersion transfer coefficient matrix (TCM) is evaluated using the Cross Appalachian Tracer Experiment (CAPTEX) data collected from six controlled releases. For simplicity, the initial tests are applied to release 2 for which the HYSPLIT has the best performance. Before introducing model uncertainty terms, the tests using concentration differences in the cost function results in severe underestimation while those using logarithm concentrations differences results in overestimation of the release rate. Adding model uncertainty 5 terms improves results for both choices of the metric variables in the cost function. A cost function normalization scheme is later introduced to avoid spurious minimal source term solutions when using logarithm concentration differences. The scheme is effective in eliminating the spurious solutions and it also helps to improve the release estimates for both choices of the metric variables. The tests also show that calculating logarithm concentration differences generally yield better results than calculating concentration differences and the estimates are more robust for a reasonable range of model uncertainty parameters. This is 10 further confirmed with nine ensemble HYSPLIT runs in which meteorological fields were generated with varying planetary boundary layer (PBL) schemes. In addition, it is found that the emission estimate using a combined TCM by taking the average or median values of the nine TCMs is similar to the median of the nine estimates using each of the TCMs individually. The inverse system is then applied to the other CAPTEX releases with a fixed set of observational and model uncertainty parameters and the largest relative error among the six releases is 53.3%. At last, the system is tested for its capability to find a 15 single source location as well as its source strength. In these tests, the location and strength that yield the best match between the predicted and the observed concentrations are considered as the inverse modeling results. The estimated release rates are mostly not as good as the cases in which the exact release locations are assumed known, but they are all within a factor of 3 for all the six releases. However, the estimated location may have large errors. 1Geosci. Model Dev. Discuss., https://doi

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“…Concentration is determined using these areas and the calibration curve determined from the standards. Dietz (1987) and Draxler (1992).…”

Section: Introductionmentioning

confidence: 99%

A personal exposure study employing scripted activities and paths in conjunction with atmospheric releases of perfluorocarbon tracers in Manhattan, New York

Lioy

Vallero

Foley

et al. 2007

J Expo Sci Environ Epidemiol

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harmless perflourocarbon tracers (PFT) released in Midtown Manhattan with approval by city agencies at separate locations, during two types of experiments, completed during each release period. Two continuous 1 h release periods separated by a 1.5 h ventilation time were completed on 3 October 2005. Stationary site and personal exposure measurements were taken during each period, and the first half hour after the release ended. Two types of scripted exposure activities are reported: Outdoor Source Scale, and Outdoor Neighborhood Scale; requiring 1-and 10-min duration samples, respectively. The results showed that exposures were influenced by the surface winds, the urban terrain, and the movements of people and vehicles typical in urban centers. The source scale exposure data indicated that local conditions significantly affected the distribution of each tracer, and consequently the exposures. The highest PFT exposures resulted from interaction of the scripted activities with local surface conditions. The range measured for 1-min exposures were large with measured values exceeding 5000 ppqv (parts per quadrillion by volume). The neighborhood scale measurements quantified exposures at distances up to seven blocks away from the release points. Generally, but not always, the PFT levels returned quickly to zero indicating that after cessation of the emissions the concentrations decrease rapidly, and reduce the intensity of local exposures. The near source and neighborhood personal exposure route results provided information to establish a baseline for determining how a release could affect both the general public and emergency responders, and evaluate the adequacy of re-entry or exit strategies from a local area. Finally, the data also show that local characteristics can produce ''hot spots''.

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Across North America tracer experiment (ANATEX): Sampling and analysis

Cited by 52 publications

References 14 publications

Source Apportionment: Findings from the U.S. Supersites Program

Source Apportionment: Findings from the U.S. Supersites Program

Weak-constraint inverse modeling using HYSPLIT Lagrangian dispersion model and Cross Appalachian Tracer Experiment (CAPTEX) observations – Effect of including model uncertainties on source term estimation

A personal exposure study employing scripted activities and paths in conjunction with atmospheric releases of perfluorocarbon tracers in Manhattan, New York

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