Following the collapse of the New York World Trade Center (WTC) towers on September 11, 2001, Loc... more Following the collapse of the New York World Trade Center (WTC) towers on September 11, 2001, Local, State, and Federal agencies initiated numerous air monitoring activities to better understand the ongoing impacts of emissions from the disaster. The collapse of the World Trade Center towers and associated fires that lasted for several weeks resulted at times in a noticeable plume of material that was dispersed around the Metropolitan New York City (NYC) area. In general, the plume was only noticeable for a short period of time following September 11, and only apparent close to the World Trade Center site. A study of the estimated pathway which the plume of WTC material would likely follow was completed to support the United States Environmental Protection Agency's 2002 initial exposure assessments. In this study, the WTC emissions were simulated using the CALMET-CALPUFF model in order to examine the general spatial and temporal dispersion patterns over NYC. This paper presents the results of the CALPUFF plume model in terms of plume dilution and location, since the exact source strength remains unknown. Independent observations of PM 2.5 are used to support the general dispersion features calculated by the model. Results indicate that the simulated plume matched well with an abnormal increase (600-1000% of normal) in PM 2.5 two nights after the WTC collapse as the plume rotated north to southeast, towards parts of NYC. Very little if any evidence of the plume signature was noted during a similar flow scenario a week after September 11. This leads to the conclusion that other than areas within a few kilometers from the WTC site, the PM 2.5 plume was not observable over NYC's background concentration after the first few days.
NATO Science for Peace and Security Series C: Environmental Security, 2011
... Rohit Mathur, Robert Gilliam, O. Russell Bullock Jr., Shawn Roselle, Jonathan Pleim, David Wo... more ... Rohit Mathur, Robert Gilliam, O. Russell Bullock Jr., Shawn Roselle, Jonathan Pleim, David Wong, Francis Binkowski, and David Streets ... 1. Byun DW, Schere KL (2006) Review of the governing equations, computational algorithms, and other components of the Models-3 ...
Because all models are a simplification of the phenomenon they aim to represent, it is often more... more Because all models are a simplification of the phenomenon they aim to represent, it is often more useful to estimate the probability of an event rather than a single "best" model result. Previous air quality ensemble approaches have used computationally expensive simulations of separately developed modeling systems. We present an efficient method to generate ensembles with hundreds of members based on several structural configurations of a single air quality modeling system. We use the Decoupled Direct Method in three dimensions to directly calculate how ozone concentrations change as a result of changes in input parameters. The modeled probability estimate is compared to observations and is shown to have a high level of skill and improved resolution and sharpness. This approach can help resolve the practical limits of incorporating uncertainty estimation into deterministic air quality management modeling applications.
Examination of model sensitivity to horizontal grid resolutions can help identify optimal comprom... more Examination of model sensitivity to horizontal grid resolutions can help identify optimal compromise in accuracy and computational efficiency for regulatory and research-grade applications of 3-D atmospheric models. In this Part III paper, the performance and sensitivity of simulated precipitation and wet deposition amounts by the MM5/CMAQ model to three horizontal grid resolutions (4-, 12-, and 36-km) are evaluated over North Carolina (NC).
Meteorological models in conjunction with air quality models are being used to simulate the trans... more Meteorological models in conjunction with air quality models are being used to simulate the transport and fate of pollutants in the atmosphere. Hence, there is a need for an extensive evaluation of the entire modeling system. In this study, several new techniques to assess the performance of mesoscale meteorological models are introduced with an emphasis on evaluating the variables and processes that have the potential to influence the air quality predictions, since errors in the meteorological fields are passed on to the air quality model.
42 43 Accurate regional air pollution simulation relies strongly on the accuracy of the mesoscale... more 42 43 Accurate regional air pollution simulation relies strongly on the accuracy of the mesoscale 44 meteorological simulation used to drive the air quality model. The framework of the Air Quality 45
Following the collapse of the New York World Trade Center (WTC) towers on September 11, 2001, Loc... more Following the collapse of the New York World Trade Center (WTC) towers on September 11, 2001, Local, State, and Federal agencies initiated numerous air monitoring activities to better understand the ongoing impacts of emissions from the disaster. The collapse of the World Trade Center towers and associated fires that lasted for several weeks resulted at times in a noticeable plume of material that was dispersed around the Metropolitan New York City (NYC) area. In general, the plume was only noticeable for a short period of time following September 11, and only apparent close to the World Trade Center site. A study of the estimated pathway which the plume of WTC material would likely follow was completed to support the United States Environmental Protection Agency's 2002 initial exposure assessments. In this study, the WTC emissions were simulated using the CALMET-CALPUFF model in order to examine the general spatial and temporal dispersion patterns over NYC. This paper presents the results of the CALPUFF plume model in terms of plume dilution and location, since the exact source strength remains unknown. Independent observations of PM 2.5 are used to support the general dispersion features calculated by the model. Results indicate that the simulated plume matched well with an abnormal increase (600-1000% of normal) in PM 2.5 two nights after the WTC collapse as the plume rotated north to southeast, towards parts of NYC. Very little if any evidence of the plume signature was noted during a similar flow scenario a week after September 11. This leads to the conclusion that other than areas within a few kilometers from the WTC site, the PM 2.5 plume was not observable over NYC's background concentration after the first few days.
NATO Science for Peace and Security Series C: Environmental Security, 2011
... Rohit Mathur, Robert Gilliam, O. Russell Bullock Jr., Shawn Roselle, Jonathan Pleim, David Wo... more ... Rohit Mathur, Robert Gilliam, O. Russell Bullock Jr., Shawn Roselle, Jonathan Pleim, David Wong, Francis Binkowski, and David Streets ... 1. Byun DW, Schere KL (2006) Review of the governing equations, computational algorithms, and other components of the Models-3 ...
Because all models are a simplification of the phenomenon they aim to represent, it is often more... more Because all models are a simplification of the phenomenon they aim to represent, it is often more useful to estimate the probability of an event rather than a single "best" model result. Previous air quality ensemble approaches have used computationally expensive simulations of separately developed modeling systems. We present an efficient method to generate ensembles with hundreds of members based on several structural configurations of a single air quality modeling system. We use the Decoupled Direct Method in three dimensions to directly calculate how ozone concentrations change as a result of changes in input parameters. The modeled probability estimate is compared to observations and is shown to have a high level of skill and improved resolution and sharpness. This approach can help resolve the practical limits of incorporating uncertainty estimation into deterministic air quality management modeling applications.
Examination of model sensitivity to horizontal grid resolutions can help identify optimal comprom... more Examination of model sensitivity to horizontal grid resolutions can help identify optimal compromise in accuracy and computational efficiency for regulatory and research-grade applications of 3-D atmospheric models. In this Part III paper, the performance and sensitivity of simulated precipitation and wet deposition amounts by the MM5/CMAQ model to three horizontal grid resolutions (4-, 12-, and 36-km) are evaluated over North Carolina (NC).
Meteorological models in conjunction with air quality models are being used to simulate the trans... more Meteorological models in conjunction with air quality models are being used to simulate the transport and fate of pollutants in the atmosphere. Hence, there is a need for an extensive evaluation of the entire modeling system. In this study, several new techniques to assess the performance of mesoscale meteorological models are introduced with an emphasis on evaluating the variables and processes that have the potential to influence the air quality predictions, since errors in the meteorological fields are passed on to the air quality model.
42 43 Accurate regional air pollution simulation relies strongly on the accuracy of the mesoscale... more 42 43 Accurate regional air pollution simulation relies strongly on the accuracy of the mesoscale 44 meteorological simulation used to drive the air quality model. The framework of the Air Quality 45
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