IV. e. Calculating the Ozone Contribution
             Estimated time:
             3 minutes
The amount of ozone per intersected polygon can be calculated using the product of the area of the intersected polygon and the ozone, divided by the area of the original census tract. This is going to add the value of ozone per census tract area together, so that the value of ozone is based on census tract area instead of the grid area it started out as.
In this exercise, you will:
  • Calculate the Ozone Contribution


                                                   Start VideoDemo

Text Version:

    1. Right Click on OzContr

    2. Click Field Calculator -> Yes

    3. Turn off Advanced and clear the text box

    4. Note: The X in HRX refers to the hour of Ozone Concentration you have been assigned

    5. In the first intersect box create the equation [IArea]* [HRX]/ [Area]

    6. Click Ok

    7. Repeat again but using the 8HrOzContr field and use the equation [IArea]*[8hr]/[Area]