Relationship between synoptic weather disturbances and particulate matter air pollution over the United States

Abstract

This study establishes connections between day-to-day variability of sea level pressure (SLP), surface air temperature (T), and precipitation (PR) and that of fine particulate matter (PM 2.5) air pollution. In particular, matrix methods were applied to quantify statistical relationships between the daily anomalies of these fields over the continental US, during the 7 year study period. The anomalies were defined as deviations from nonoverlapping 2 week averages to focus on synoptic scales. The main effect of synoptic weather systems on day-to-day variability of PM 2.5 air pollution consists of formation of a high-pollution area behind propagating anticyclones and a low-pollution region in the wake of cyclones. This property is rationalized by the fact that the regions just west of the eastward-propagating cyclones (or anticyclones) experience the cyclonic (anticyclonic) conditions detrimental to (favorable for) PM 2.5 accumulation for the longest period of time. The advection of climatological PM 2.5 concentrations by anomalous winds associated with propagating weather systems may also contribute to the formation of the above PM 2.5 anomalies, but does not represent a dominant effect. This "synoptically controlled" PM 2.5 variability accounts for as much as 30% of the total high-pass filtered particulate matter (PM) variance in the midwest region throughout the year (irrespective of season), while it is substantially less pronounced along the coasts and in the southern US. The authors argue that the apparent correlations between PM and T, as well as PM and PR anomalies do not imply causality, but rather show that these quantities are commonly related to the external factors associated with the life cycle of midlatitude synoptic storms. Copyright 2010 by the American Geophysical Union.