So I started thinking about what might a measure of continuous air quality progress be? For example, could we use ambient air quality adjusted for meteorological conditions and transport?
One way to do this might be to use S. T. Raošs long term analysis. His approach, in effect, seems to adjust for meteorology. Could we use Raošs long term analysis technique on ozone flux, i.e., the difference between the downwind ozone and the upwind ozone, in order to subtract transport?
One specific approach might be to develop a data set for one city for which we have wind field data and a set of all possible upwind monitors (essentially ŗbackground˛ monitors at every compass point surrounding the city). Then, on a daily basis, construct the ozone flux time series choosing the appropriate background monitor based on that dayšs (or morningšs) predominate wind direction. Finally, apply Raošs technique to the flux measurement and examine the trend.
A secondary analysis could take into account precursors (VOC and NOy or NOx) but might be more time consuming to implement. The idea would be to adjust for precursor transport into the area by running a single ozone episode with fluctuating boundary conditions.
One way to do this might be to examine the range of precursor concentrations during the period of analysis. Then perform several runs of the photochemical model with this range in boundary condition inputs. (Reduce the number of runs by picking only a few sets of conditions; interpolate the model results for the intermediate points.) Finally, add this adjustment to the ozone flux adjustment described above to calculate the long term ozone trend for which the area itself is responsible. Comments?
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