Meteorological influences on extreme duration PM2.5 air pollution episodes

Abstract:

The public health impact of poor air quality events increases as their duration lengthens. Potentially hazardous air pollution episodes result when meteorological conditions facilitate the accumulation and/or formation of airborne pollutants in the near-surface atmosphere and may persist if ventilation, vertical escape, and/or scavenging of the pollutants fails to occur. Here, we analyze particulate matter (PM) observations from a suite of globally-distributed locations, characterize the intensity and persistence of extreme duration above-EPA/WMO-standard PM_2.5 pollution events, and examine the role of meteorological factors in their occurrence. We focus on the atmospheric phenomenon of air stagnation and its constituent meteorological components (dry day occurrence and light surface and upper air wind speed occurrence) and characterize the role of each on observed extreme duration episodes. Based on this observational analysis, we then use an ensemble of CMIP5 historical and high-emission scenario simulations to examine the occurrence of model-simulated stagnation and stagnation component persistence. We characterize extreme duration stagnation episodes within the multi-model ensemble and assess the response of stagnation persistence to enhanced mid-twenty first century radiative forcing.