MAPPING LIGHT POLLUTION ON WINONA STATE UNIVERSITY CAMPUS, WINONA, MN

The beauty and quality of the night sky have diminished over the last few decades due to increasing amounts of light pollution from artificial sources. According to the International Dark-Sky Association, light pollution is the excessive or inappropriate use of artificial light, resulting in high costs from wasted energy, reduced nighttime visibility for night sky viewing, and disruptions in nocturnal animal behavior. While a community may not notice light pollution until the stars disappear, it is one of the simplest types of pollution to address through better lighting practices and fixtures and the results can be immediate.

A low-resolution light pollution survey of the city of Winona, MN, was completed in 2010 and identified the Winona State University (WSU) campus as one of the brightest areas within the city. The goal of the current study is to focus on the WSU campus itself and map light pollution at a higher resolution to compare with the darker skies outside of the city. We selected two field areas, one within and around the WSU main campus and the other 5 km south of Winona in farmland on top of the bluffs representing a nearby dark sky location. Data were taken on clear, moonless nights following a pre-determined sampling scheme at each field area. Multiple measurements of sky brightness (Unihedron Sky Quality Meter) and ambient light (Extech EasyView Digital Light Meter) were recorded along with location on a Trimble GPS unit. These data are being mapped electronically using standard Kriging methods in ArcGIS, creating high-resolution spatial interpolation contour maps to show the relationship between the sky brightness and ambient light for each field area. Initial results show that while the WSU main campus is very bright, the amount of light pollution diminishes rapidly away from campus while within the city. However, the light pollution on and near campus is much worse than what is observed even a few kilometers away in the dark sky field area. We are currently mapping the types of light sources on the WSU campus to identify potential improvements to campus lighting practices that will help preserve the dark skies on campus and potentially decrease energy costs for the university.