Collaborative Research: Wintertime INvestigation of Transport, Emissions, and Reactivity (WINTER)

Georgia Tech Research Corporation, Atlanta GA

Investigators

Abstract

This award will fund the deployment of a research aircraft in a study to observe wintertime pollution in the Northeastern United States. While there have been a number of studies that have sampled atmospheric chemistry in the warm season, there have been relatively few studies in the cool season and none with the advanced instrumentation that the scientific community now possesses. This is important because the processes that affect how much pollution is created and how far it travels depends significantly on water vapor and sunlight, both of which are dramatically different in summer and winter. This study will examine how these processes work in cold temperatures and low sunlight and provide input to numerical modelers to help improve forecasts and provide guidance for policymakers on how to best reduce harmful air pollution events. The Wintertime Investigations of Transport, Emissions, and Reactivity (WINTER) project will take place in early 2015. The main goal is to provide observations needed to develop a deeper understanding of the chemical and physical processes which govern the spatial distribution of anthropogenic pollutants during winter. The researchers argue that a majority of observations in polluted mid-latitude regions have been in summer, when plentiful sunlight and water vapor lead to the rapid oxidation of NOx and volatile organic compounds (VOCs) by OH. In the winter months when OH concentrations are much lower and temperatures are colder, different oxidation pathways are expected to be more important. This leads to the slower oxidation of reactive pollutants such as nitrogen oxides, VOCs and sulfur dioxide, resulting in longer atmospheric lifetimes and therefore the transport of these species over wider geographic areas. The colder winter temperatures also change the equilibrium gas-particle partitioning of semi-volatile species (e.g. HNO3) favoring the formation of particles and resulting in seasonal changes in dominant aerosol components. For example, studies have shown that inorganic nitrogen is a much higher component of the aerosol in the winter. The three primary research objectives are: 1) Characterize the chemical transformations of wintertime emissions via multiphase, nocturnal, and photochemical processes, 2) Assess the dominant mechanisms of secondary aerosol formation and quantify the geographical distribution of inorganic and organic aerosol types during winter, and 3) Constrain wintertime emission inventories of key pollutants for urban areas, power plants, and agricultural areas, and characterize their export over the North Atlantic. In addition to the broader impacts stated above, a significant number of students would be involved in the field campaign and data analysis activities. Outreach activities will include a media day, visits by K-12 students, and project updates through social media.