MODELS
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Emissions Modeling
Significant spatial and temporal variability in emissions from oil and gas sites
Emissions from oil and gas operations vary spatially and temporally
Conventional emission reporting methods are mostly based on annual and basin average emission factors and fail to capture spatial and temporal variability in emissions
We developed emission inventories in Marcellus covering >200,000 sites with:
Species-resolved emission rates and compositions
High temporal resolution
High spatial resolution
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Temporally and spatially resolved inventories were developed based on data from publicly available datasets and tools
Species-level estimates were developed using consistent and source-specific composition profiles
Air Quality Modeling
Emissions estimates are coupled with atmospheric models to predict air quality impacts
Modeling in the Eagle Ford Shale revealed sources could impact ambient atmospheric concentrations more than 50 km away
Modeling domains in the TRACER framework are selected to encompass all potentially impactful emission sources (i.e., being typically larger than 50 km × 50 km)
Figure: For each hour of a 3-month modeling simulation, what were the concentration contributions from sources withing n km of a centralized receptor point compared to the contribution from sources within 100km of the same point
Figure: Arrangement of sources around the centralized receptor point
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Explore how TRACER has been used
Applications: Emission event reconstruction, state implementation plans, etc.
TRACER modeling produces ambient concentration predictions with high spatial, temporal, and chemical specificity. This allows for detailed comparisons with ambient measurements to conduct source attribution or identify large, non-routine emission events unidentified by the emissions model. High specificality also allows for granular impact assessments (e.g., “what if” scenarios relevant to state implementation plans).
Applications: health-effects studies, demonstrating attainment for National Ambient Air Quality Standards (NAAQS)
TRACER predictions can be downscaled to various spatial and temporal resolutions for studies interested in longer-term averages or spatially variable impacts
Applications: demonstrating attainment for National Ambient Air Quality Standards (NAAQS), environmental justice studies, evaluating emissions inventories
Coarse emissions datasets can be combined with operational information to upscale emissions estimates in space and time. These distributions can be combined with chemical transport models to evaluate the impact of aggregating emissions at various spatial and temporal scales on predicted distributions of secondary pollutant (e.g. ozone) concentrations.
Model Transport and Atmospheric Chemistry Framework
The TRACER framework can be configured using most air quality models that accept point- and area-source emissions inputs allowing modelers to develop fit-for-purpose solutions for their specific-use case. Dispersion and chemical transport models were used to develop the TRACER framework in a series of case studies.
See generalized and detailed air quality modeling framework flowcharts here.
Air quality models used in TRACER case studies
Dispersion Models:
CALPUFF
AERMOD
Single Equation Gaussian Implementation
Chemical Transport Models (CTMs):
Comprehensive Air Quality Model with Extensions (CAMx)
Exposure Modeling
COMING SOON!