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Student Research

Haze Events and Visibility Variations for Several Sites across New Hampshire

Karen Thorp

Particulate matter pollution is the major cause of reduced visibility (haze) in several parts of the United States, including many of our national parks. These air pollutants come from a variety of natural and manmade sources including windblown dust, soot from wildfires, motor vehicles, electric utility and industrial fuel burning, and manufacturing operations. Previous studies have shown that air quality in New England can be significantly affected by pollution transported into the region from upwind sources. Even observations at the top of Mt. Washington have shown that visibility can be degraded by as much as a third during noteworthy haze events. The climatic variation across New Hampshire (NH) is one of the largest in the country, even though NH covers a relatively small geographic area. The region is influenced by a variety of air masses (polar, tropical, continental, and maritime), has elevations ranging from sea level to greater than 2000 m, and is typically located within the path of significant storm tracks.

This investigation examines the characteristics of NH haze events and the variability of reduced visibility occurrences across the state. The comparative study primarily uses hourly surface observations from four different New Hampshire locations during the summer of 2006 (May through September). The four locations, chosen for their differences in elevation and climatic conditions, include: Pease International Airport, Concord Municipal Airport, Mt. Washington Observatory, and Berlin Municipal Airport. The study provides a quantitative overview of summer 2006 visibility impairment events which include time periods of haze, fog, and precipitation reported at the different sites. Haze events are further examined using AIRMAP air quality measurements from across NH in combination with the Hybrid Single Particle Lagrangian Integrated Trajectory (HYSPLIT) model to determine the chemical composition and quantity of the haze particulates, the air mass trajectories, and the likely pollution source regions.