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REGIONAL MODELING OF WEEKEND/WEEKDAY EMISSIONS CHANGES
Project No. A-69
Leaders: A.M. Dunker
D. R. Lawson
Scope and Objective
The main objectives of this study are to improve regional emission inventories, models, and control strategies by simulating the impact of weekday/weekend emission changes. The objectives will encompass three steps: 1) Review and improve the weekend emission inventory in the eastern U.S., 2) Test the ability of a regional model to simulate the impact of weekday/weekend emission changes on O3, and 3) Determine what extent the emission changes in upwind cities affect downwind cities and rural areas.
Current Status and Future Program
CRC funded two projects on modeling the impact of weekday/weekend emission changes in Los Angeles. Project A-36 focused on simulation of an episode during the Southern California Ozone Study (SCOS) in 1997. In Project A-56, Los Angeles emissions were projected to 2010, and the simulated weekday/weekend ozone changes in 2010 were compared to those obtained with emissions for 1997. NREL funded a modeling study of a weekday/weekend ozone episode in southeast Michigan in 2002. Although the modeling domain was larger than southeast Michigan, the review of the weekend emission inventory and the updates to the inventory were confined to southeast Michigan.
To date, there has apparently been no modeling study of weekday/weekend ozone (and PM) changes over a large regional domain using a consistent set of weekend emission changes for the entire domain. Simulating a weekday/weekend episode provides a more stringent test of a regional model (and the associated emission inventory) than simulating a weekday episode. Because the weekend emission reductions are substantial, a weekday/weekend episode can test the model’s ability to simulate the effects of emission reductions. Modeling a regional weekday/weekend episode is also of interest because the emission changes in one urban area may impact ozone concentrations in a downwind urban area, delayed by the time required for atmospheric transport. Thus, the weekday/weekend ozone changes in a large region may be different or more complicated than those seen in Los Angeles, which has no large urban area upwind.
An ozone episode in the eastern U.S. containing at least one weekend will be chosen. The modeling domain will cover most or all of the eastern U.S. with fine grids over the major urban areas. The weekend emission inventory for the entire
REGIONAL MODELING OF WEEKEND/WEEKDAY EMISSIONS CHANGES (continued)
region will be reviewed and adjustments made as necessary to apply a consistent set of assumptions and to use the latest information on weekend activity data. A regional model (CAMx or CMAQ) will be used to simulate the episode. Model predictions for ozone (and other pollutants, if possible) will be compared to ambient measurements within and downwind of urban areas. Analyses of model results, sensitivity tests, and applications of probing tools will be used as appropriate to determine the impact of weekend emission changes in large urban areas on downwind urban and rural areas.
Project deliverables will include a regional emission inventory updated for weekday/weekend changes, quarterly reports, and a final report, part of which is a draft journal article with recommended improvements in modeling longer ozone and PM episodes that include weekends, especially improvements to the weekend regional emission inventory for on-road and off-road vehicles. This project is in the development stage now and a final work statement will be prepared for a solicitation before the end of 2008.
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