Differing atmospheric scales of motion and their impact on air pollutants

Identifying the dominant atmospheric scale of motion over a given airshed can be of great importance for many applications such as air pollutants dispersion, pollen dispersion and wind energy. In this work, a method is proposed for differentiating between the synoptic, meso and local scales that can be applied on a daily basis from data collected at several wind-measuring sites in a given airshed. The method is based on the daily mean quantitative measure of wind recirculation measured at each site, and the mean and standard deviation between sites. The method is applied to a 5-year time series of wind observations at seven sites in the Tel Aviv airshed on the East Mediterranean Sea. The high frequency of synoptic-scale dominant flows is found during winter and December in particular, whereas high dominance of mesoscale flows is found during October. The coastal location of the airshed causes the land-sea breeze to overrule local-scale variations. While NO_x and SO₂ concentrations are shown to increase as the dominant scale is smaller, O₃ concentrations decrease as a result of titration with NO_x on the one hand and the contribution of long-range transport on the other.