Particulate Matter in the Summer Season and Its Relation to Synoptic Conditions and Regional Climatic Stress – the Case of Haifa, Israel

Relatively high concentrations of particulate matter (PM) are characteristic to Israel and the Middle East. This is mostly attributed to natural dust storms and partly to anthropogenic sources, local, or remote. The research deals with relations between concentrations of PM₁₀ and PM_2.5, and between synoptic conditions and regional climatic stress. Our particular focus is the summer, a season with no dust outbreaks when mostly one synoptic system, the Persian Trough prevails over the region, with associated northwesterly Etesian winds. Therefore, the “climate to environment” approach to distinguishing among PM concentrations by classes of synoptic systems is not very successful in the summer. In contrast, the climatic stress index (CSI), representing the “environment to climate” approach, was found positively correlated with PM concentrations in Haifa, Israel, and more effective in explaining inter-diurnal variations of PM pollution. Synoptic analysis performed through composite anomaly maps for days with higher and lower PM concentration, indicates a weakening of the Etesian winds in days with high CSI. On the one hand, the weaker winds reduce imported PM, but, on the other hand, the lower marine inversion in days with high CSI enhances PM pollution from local sources, by weakening the dispersion mechanisms, both vertical and horizontal. The higher level of PM pollution in days with high CSI indicates dominance of the local PM sources. The positive correlation between climatic stress and PM pollution, and increased climatic stress associated with global and regional warming, necessitate further tightening of control on anthropogenic pollution sources.