Implementing the Empirical Kinetic Modeling Approach

The basic EKMA procedure involves four steps, each outlined below. More detailed information is found on the appropriate linked pages:

Step 1: select the five days with the highest maximum hourly ozone concentrations observed at each site affected by the urban area over the past three years.
Step 2: for each of these days, estimate the 6-9 am VOC/NO_x ratio prevailing in the urban core
Step 3: Using the appropriate input data, run the OZIP model to generate ozone isopleth diagrams for each day. These diagrams denote sensitivity of peak hourly ozone concentrations to locally generated precursors, given a set of current accompanying conditions, such as a specified concentration of transported ozone from upwind sources.
Step 4: using the ozone concentrations from Step 1 and the ratios from Step 2, establish a starting point on each of the ozone isopleths from the OZIP model. From the starting data, the modeler is able to calculate the percentage reduction needed to meet a particular air quality standard. Several possibilities for this step are possible, and are explained in detail in the appropriate reading. In some cases, a single day-specific ozone isopleth diagram suffices for evaluating needed reductions. In some instances, it is neccessary to generate a second set of isopleth diagrams. This is normally the case if there are changes in the base case scenario, such as concurrent reduction in emissions and in transported ozone. Again, both scenarios will be describe in the reading on Step 4.

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