ARB Research Seminar

This page updated June 19, 2013

Forecasting Air Pollution and Human Exposure on Scales of Individual Streets

Gary Geernaert and Finn Palmgren Jensen, National Environmental Research Institute, Department of Atmospheric Environment, Roskilde, Denmark

October 22, 2001
Cal EPA Headquarters, 1001 "I" Street, Sacramento, California



In order to develop a low-cost, portable system for human exposure research as well as to provide operational weather and air pollution forecasting on scales extending down to individual street canyons, NERI developed a modeling system (called the THOR system). The THOR system uses a set of nested meterological and air chemistry models, which is driven by Internet-based input data. The inputs include meteorological data fields which are provided by NCEP (NOAA), and emission inventories available from the European Monitoring and Evaluation Programme (EMEP) and other national inventories. At present, the model system produces 36-hour forecasts of air pollutants, including NOₓ, O₃, SO₂, CO, and benzene, and meteorology (winds, temperature, humidity, air pressure, boundary layer height, and precipitation rates). Because of limited computer power, the operating domain of the model extends from northern Africa up to the Arctic, and from east Greenland to central Russia.

One unique feature of the THOR system is its street canyon model (OSPM - Operational Street Pollution Model). The OSPM is a primitive equation 3-D model system, which predicts the wind-induced vortex structure and turbulent transport caused by wind blowing oblique to the street axis at roof top. Using information on street configurations, meteorology, and street-based emissions, model calculations have revealed that differences of concentrations on the two sides of individual streets are significant enough to affect site selection of monitoring stations and assessments of health risk. The model, as part of the THOR system, also supports the data collection requirements of the Danish urban monitoring program, as part of the European Union's requiremens for member states. In order to document the model accuracy, validation studies against field measurements in Copenhagen, Oslo, Brussels, and Beijing, have been carried out since 1998. In general, there is excellent agreement between model predictions and field measurements. Because of its portability and flexibility, there are programs which are presently underway to demonstrate the utility of the model system as a forecast and assessment tool, in Rumania, Lithuania, Botswana, Greece, Spain, Norway, Sweden, Germany, and Thailand.

In the seminar, Dr. Geernaert will describe the history, evolution, and applications of the THOR system, with special reference to human exposure and assessments. Several epidemiology studies will be described, e.g., the Danish Children's Cancer Study, which utilized THOR air pollution forecast products as part of the experimental design and subsequent analysis tasks. In addition, both Dr. Geernaert and Dr. Finn Palmgren will present the next steps for model development and subsequent applications to the health sector. Special emphasis will be on an ongoing Danish research program on atmospheric particulates, and on an upcoming research program on aerobiology. The presentation will highlight how the results of these programs will be assimilated into the THOR forecast system as new features.

Speaker Biography

Dr. Geernaert is presently the director of NERI's Department of Atmospheric Environment. This department is responsible for coordinating and/or carrying out all research, monitoring, forecasting, and policy analysis associated with air pollution in Denmark. With over 80 scientific publications, and four books, Dr. Geernaert's primary expertise is in meteorology, air pollution, air-sea interactions, remote sensing, and policy analysis. He is also chairman of the Danish Atmospheric Research Society. Dr. Geernaert received his B.S. in the Dept of Land, Air, and Water Sciences (UC Davis) in 1977, and Ph.D. in atmospheric sciences from the University of Washington (Seattle) in 1983. Prior to joining NERI in 1994, he was a program manager in the US Office of Naval Research (Arlington, VA). He also holds adjunct faculty positions at the University of Copenhagen and the University of California (San Diego).

Dr. Finn Palmgren is presently the manager of all air quality monitoring activities in Denmark, including the background, urban, and Arctic programs. In this capacity, he alaso oversees the Danish contribution to the European Union's strategy on air quality monitoring, and he participates in the process of designing future air quality directives for the European Union (EU). In 1999, he chaired the EU study group responsible for designing the NO₂ air quality directive. Finn Palmgren has published over 100 scientific articles and three books. He received his Ph.D. from the Danish Technical University in high energy physics, in 1970.

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