Air Quality Modeling

7.6 Relevant Applications

7.6.5 Assessment of Ozone Abatement Strategies for the Green Olympic
Ozone concentrations in Beijing during the summer time can exceed the national Class II standard (200 ug/ m3 for hour). This is the most threat for Green Olympic in 2008 and the public notification is required if the concentration exceeds 120 ppb (240 µg/m3), which is the EU guideline. A modeling analysis was carried out to determine the effectiveness of emission reduction scenarios in reducing peak concentrations (Tsinghua University, 2006).

The meteorological model used in this work was the MM5 model Version 3.7, which provided input for the air quality model CMAQ. Three-domain one-way nesting was used in MM5-Models-3/CMAQ modeling. Lambert projection was used with the two true latitudes of 25oN and 40oN. Domain 1 covers most area of East Asia with 36 x 36km resolution to generate appropriate boundary condition for inner domains. Domain 2 includes Beijing, Tianjin, Hebei and parts of several surrounding provinces. The innermost, with 4km grid spacing, consists of whole Beijing and part of Tianjin and Hebei province. 12 vertical layers from surface to tropopause were employed with denser layers in the lower atmosphere.

The modeling episode covers the whole months for the Olympic Games. They occurred from 17 July to 20 September. Other episodes with high ozone concentrations during July, August and September in 2001 to 2005 are also analyzed. Wind directions were different for these episodes, which were considered representative of the conditions that most often result in high ozone conditions in the region. The statement was made that high ozone concentrations in Beijing area associated with local emissions and significant regional sources.

Three emission scenarios Regular, Strict and Extremely Strict scenarios considered are summarized. Combustion, industry and transportation sectors are controlled in different measurements, according to the rigorous extension for implementation.

Response to these scenarios was analyzed in several ways: Effect on maximum ozone concentration domain-wide, Effect on total amount of ozone above 200 µg/m3 and Effect of emission reductions for certain time periods.

This study illustrates the approach that is usually adopted in developing policies for pollutant abatement, that is, develop a set of emission reduction scenarios, and evaluate their effectiveness using a model or models. In practice, the scenarios will have to take into account practical factors, the most important of which will usually be the cost and availability of emission control equipment.