Multiscale plume transport from the collapse of the World Trade Center on September 11, 2001

Georgiy Stenchikov*, Nilesh Lahoti, David J. Diner, Ralph Kahn, Paul J. Lioy, Panos G. Georgopoulos

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

19 Scopus citations


The collapse of the world trade center (WTC) produced enhanced levels of airborne contaminants in New York City and nearby areas on September 11, 2001 through December, 2001. This catastrophic event revealed the vulnerability of the urban environment, and the inability of many existing air monitoring systems to operate efficiently in a crisis. The contaminants released circulated within the street canyons, but were also lifted above the urban canopy and transported over large distances, reflecting the fact that pollutant transport affects multiple scales, from single buildings through city blocks to mesoscales. In this study, ground-and space-based observations were combined with numerical weather forecast fields to initialize fine-scale numerical simulations. The effort is aimed at reconstructing pollutant dispersion from the WTC in New York City to surrounding areas, to provide means for eventually evaluating its effect on population and environment. Atmospheric dynamics were calculated with the multi-grid Regional Atmospheric Modeling System (RAMS), covering scales from 250 m to 300 km and contaminant transport was studied using the Hybrid Particle and Concentration Transport (HYPACT) model that accepts RAMS meteorological output. The RAMS/HYPACT results were tested against PM2.5 observations from the roofs of public schools in New York City (NYC), Landsat images, and Multi-angle Imaging SpectroRadiometer (MISR) retrievals. Calculations accurately reproduced locations and timing of PM2.5 peak aerosol concentrations, as well as plume directionality. By comparing calculated and observed concentrations, the effective magnitude of the aerosol source was estimated. The simulated pollutant distributions are being used to characterize levels of human exposure and associated environmental health impacts.

Original languageEnglish (US)
Pages (from-to)425-450
Number of pages26
JournalEnvironmental Fluid Mechanics
Issue number5
StatePublished - Oct 2006
Externally publishedYes

Bibliographical note

Funding Information:
Acknowledgements This work was sponsored by USEPA grant CR827033. Additional support was provided by a supplement to the NIEHS EOHSI center grant P30 ES05022. We thank Praveen Amar of NESCAUM for providing plume photographs; Jennifer Bosch of the Rutgers University Institute of Marine and Coastal Sciences for providing AVHRR SST retrievals; the developers of RAMS and HYPACT, Bob Walko and Craig Tremback, for consulting on RAMS/HYPACT modifications; and Linda Everett of EOHSI for help with editing and manuscript preparation. Georgiy Stenchikov was partially supported by NJDEP grant SR04-048. The research of David Diner and Ralph Kahn is supported, in part, by the MISR project at JPL, under contract with NASA. Ralph Kahn is also supported by the NASA Climate and Radiation Research & Analysis program, under H. Maring. We thank Catherine Moroney of JPL for the special stereo processing of the MISR WTC data.


  • 9/11
  • Aerosol plume
  • Hybrid Particle and Concentration Transport Model
  • Multi-angle Imaging Spectro Radiometer
  • Particulate matter
  • Regional Atmospheric Modeling System
  • Terrorist attack
  • Transport
  • Urban pollution
  • World Trade Center

ASJC Scopus subject areas

  • Environmental Chemistry
  • Water Science and Technology


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