Greater Yellowstone Network
The Greater Yellowstone Vital Signs Network (GRYN) includes 3 national park units in Wyoming and Montana: Yellowstone National Park (NP), Grand Teton NP, and Bighorn Canyon National Recreation Area (NRA). GRYN encompasses a wide variety of ecosystems ranging from alpine tundra to lowland desert steppe. Yellowstone NP and Grand Teton NP make up the core of the Greater Yellowstone Ecosystem, one of the largest, relatively intact natural areas in the contiguous United States.
Yellowstone NP and Grand Teton NP are Class I air quality areas, receiving the highest protection under the Clean Air Act. Bighorn Canyon NRA is a Class II air quality area and also receives protection under the Act. Air quality issues of concern in the GRYN include atmospheric deposition effects and visibility impairment from fine particle haze. Nitrogen deposition can cause changes in water chemistry, including enrichment or eutrophication and loss of acid-neutralizing capacity. Nitrogen may also affect soil chemistry, soil microorganisms, plants, and trees. Excess nitrogen deposition can cause changes in plant community structure and diversity, with native species being replaced by invasive and exotic species. An ozone injury risk assessment indicates the risk of injury to vegetation is low throughout the network.
Yellowstone NP has a full suite of on-site air quality monitoring, including monitoring for wet and dry atmospheric deposition, wet mercury deposition, ozone, and visibility. Limited snowpack sampling is done in Grand Teton NP to characterize atmospheric deposition loading from snow. Air quality monitoring is not done in Bighorn Canyon NRA.
The Network map below provides information on air quality monitoring. Ozone, sulfur dioxide, dry deposition, and meteorology are collected by the Clean Air Status and Trends (CASTNet) and Gaseous Pollutant Monitoring (GPMN) networks. Ozone is also monitored with passive samplers and portable continuous analyzers. Wet Deposition is monitored through cooperation with National Atmospheric Deposition Program/National Trends Network (NADP/NTN). The Mercury Deposition Network (MDN), part of NADP, collects precipitation samples that are analyzed for mercury. Visibility is monitored as part of the Interagency Monitoring of Protected Visual Environments (IMPROVE). Additional details on these parameters are described in Air Quality Monitoring.
Air quality monitoring in or near the network is indicated on the map by symbols, with the blue line showing the approximate borders of the network. The legend shows the symbols for the type of monitoring present, with NPS park units in green. Class I areas have linkable access to ARIS information.