Reductions in Haze Across the United States Since the Early 1990s Visualized Using WinHaze Simulated Photographs

Background

The effects of the changes in the haziest bext on various scenes were simulated using the WinHaze 2.9.9.1 model (Air Resource Specialists, Fort Collins, CO, http://www.air-resource.com/resources/downloads.html). WinHaze incorporates aerosol and radiative transfer modules with image processing to synthesize images representing air quality and environmental conditions (Malm et al., 1983; Molenar et al., 1994). Model inputs require specifying either speciated particulate concentrations, species-dependent hygroscopic and optical properties (i.e., mass extinction efficiencies) and relative humidity, or measured or reconstructed aerosol optical properties such as bext. The haziest reconstructed bext values corresponding to the beginning and end of trend periods were input to illustrate changes in the scene corresponding to the calculated trends. Scenes were simulated for approximately 50 national parks and wilderness areas with valid trends in bext.

SanGorgonioCA_SAGO_1990_2012_g90

Data

PDF file containing images from all simulated sites

Directory containing images for individual sites.

Publications

Hand, J.L., B.A. Schichtel, W.C. Malm, S. Copeland, J.V. Molenar, N. Frank, M. Pitchford, (2014)  Widespread reductions in haze across the United States from the early 1990s through 2011, Atmospheric Environment, 94, 671-679, http://dx.doi.org/10.1016/j.atmosenv.2014.05.062, 2014.