Abstract: In 2018, Solar Cycle 24 entered a deep solar minimum. During this period, we collected night sky brightness data at Cosmic Campground International Dark Sky Sanctuary (CCIDSS) in the USA (2018 September 4–2019 January 4) and at Aotea/Great Barrier Island International Dark Sky Sanctuary (AGBIIDSS) in New Zealand (2018 March 26–August 31. These sites have artificial-light-pollution-free natural night skies. The equipment employed are identical Unihedron SQM-LU-DL meters, used as single-channel differential photometers, to scan the sky as Earth rotates on its axis. We have developed new analysis techniques which select those data points which are uninfluenced by Sun, Moon, or clouds to follow brightness changes at selected points on the celestial sphere and to measure the brightness of the airglow above its quiescent level. The 2018 natural night sky was measured to change in brightness by approximately 0.9 mag arcsec−2 at both locations. Preliminary results indicate the modulations of the light curves (brightness versus R.A.) we observed are related in complex ways to elements of space weather conditions in the near-Earth environment. In particular, episodes of increased night sky brightness are observed to be contemporaneous with geomagnetic activity, increases in mean solar wind speed, and some solar proton/electron fluence events. Charged particles in the solar wind take days to reach near-Earth environment after a coronal hole is observed to be facing in our direction. Use of this information could make it possible to predict increases in Earth’s natural night sky brightness several days in advance. What we have learned during this solar minimum leads us to search for other solar driven changes in night sky brightness as the Sun begins to move into solar maximum conditions.
Keywords: Darkness; night sky brightness; United States; New Zealand; Sun; space weather; solar wind
Abstract: This paper aims to examine the economic impact from dark-sky tourism in national parks in the USA on the Colorado Plateau. The Colorado Plateau is a region encompassing parts of Arizona, Colorado, New Mexico and Utah that is known for its dark, star-filled night skies. Tourists in national parks are increasingly interested in observing this natural recreational amenity – especially considering that it is an ecological amenity that is quickly disappearing from the planet. Using a 10-year forecast of visitors to the national parks and using standard input-output modeling, it is observed that, for the first time anywhere, the value of dark skies to tourism in this area. The authors find that non-local tourists who value dark skies will spend $5.8bn over the next 10 years in the Colorado Plateau. These tourist expenditures will generate $2.4bn in higher wages and create over 10,000 additional jobs each year for the region. Furthermore, as dark skies are even more intense natural amenity in the non-summer months, they have the ability to increase visitor counts to national parks year-round and lead to a more efficient use of local community and tourism-related resources throughout the year.
Keywords: Society; tourism; Colorado Plateau; United States; astrotourism
Abstract: Washington State Department of Transportation (WSDOT) evaluated continuous roadway lighting on mainline freeway segments in Washington State. An extensive literature review on the safety performance of roadway lighting was completed. As part of this research effort WSDOT developed multivariate random parameter (RP) models with specific lighting variables for continuous lighting on mainline freeway segments. Roadway lighting is often used as a countermeasure to address nighttime crashes and this research evaluates common assumption related to roadway lighting. The models developed for this research use crashes from the end of civil dusk twilight to the start of civil dawn twilight since lighting systems are of limited value outside these timeframes. Natural light conditions were estimated for crashes based on location and time of the crash event. Based on the RP results, the research team concludes that the contribution of continuous illumination to nighttime crash reduction is negligible. In addition to the findings on safety performance, a pilot LED project on US101 demonstrated that LED roadway lighting can significantly increase energy efficiency and environmental stewardship (e.g., reducing greenhouse gas emissions) while maintaining safety performance outcomes. The research team recommended modification to WSDOT design policy, including removal of the requirement of continuous mainline lighting and reduction of lighting where segment specific analysis indicates appropriate.
Abstract: Light pollution contributes to the degradation and reduction of habitat for wildlife. Nocturnally nesting and hatching sea turtle species are particularly sensitive to artificial light near nesting beaches. At local scales (0.01–0.1 km), artificial light has been experimentally shown to deter nesting females and disorient hatchlings. This study used satellite-based remote sensing to assess broad scale (~1–100s km) effects of artificial light on nesting patterns of loggerhead (Caretta caretta), leatherback (Dermochelys coriacea) and green turtles (Chelonia mydas) along the Florida coastline. Annual artificial nightlight data from 1992 to 2012 acquired by the Defense Meteorological Satellite Program (DMSP) were compared to an extensive nesting dataset for 368, ~1 km beach segments from this same 21-year period. Relationships between nest densities and artificial lighting were derived using simultaneous autoregressive models to adjust for the presence of spatial autocorrelation. Though coastal urbanization increased in Florida during this period, nearly two-thirds of the surveyed beaches exhibited decreasing light levels (N = 249); only a small fraction of the beaches showed significant increases (N = 52). Nest densities for all three sea turtle species were negatively influenced by artificial light at neighborhood scales (<100 km); however, only loggerhead and green turtle nest densities were influenced by artificial light levels at the individual beach scale (~1 km). Satellite monitoring shows promise for light management of extensive or remote areas. As the spectral, spatial, and temporal resolutions of the satellite data are coarse, ground measurements are suggested to confirm that artificial light levels on beaches during the nesting season correspond to the annual nightlight measures.
Abstract: The purpose of this thesis is to examine the body of evidence concerning light pollution and exposure to artificial light and determine if the scientific research warrants regulatory oversight in the United States. The first question that guided this effort was: Does improper artificial lighting and exposure to light-at-night constitute a risk to human health and safety? The follow up question being: Is light pollution a concern to ecological systems, and if so to what extent? A comprehensive literature review was conducted to ascertain the status of the research—if any—in these two areas and what the findings were. The overarching purpose of this thesis was to answer the primary question: Does the scientific research on light pollution and exposure to light-at-night exposure make a case for regulatory oversight, within the mandate of the EPA? The questions were illuminated by conducting a thorough literature review, doing an informal email survey, and by in-depth interviews with people researching artificial light and with individuals in the EPA. The study concluded that there is no ready consensus to be reached in this area. Such a disparate topic as light pollution does not readily lend itself to an easy answer. However, the findings show that light pollution and light-at-night exposure do have some negative impact. This is especially true in regards to the night sky and the biota. Whether the EPA should be involved in regulating it is not entirely clear. Their mission statement leads one to presume that certain effects of light pollution do fall under their mandate. More research to quantify the effects of artificial light on humans is critically needed to show causation between artificial light exposure and health problems.
Keywords: Society; law; policy; public policy; light pollution; regulation; United States; regulation
