UV and Ozone
Ultraviolet radiation (UV) and ozone was monitored at Denali as part of a network of fourteen national parks established to understand the effects of UV radiation at both local and global scales. Although UV is a natural form of radiation, humans and ecosystems are being exposed to high levels of UV as the earth’s ozone layer is depleted. Ozone high in the stratosphere filters out UV radiation, but this layer is being jeopardized by man-made pollutants, chlorofluorocarbons (CFCs) and related compounds, that destroy the ozone molecules. Despite international treaties to phase out the use of CFCs and other ozone depleting chemicals, these chemicals persist in the upper atmosphere and continue to damage our UV shield.
Seasonal "ozone holes", where the ozone layer is particularly thin, are greater at higher latitudes. Denali National Park is well positioned as a site for measuring changes in UV radiation and ozone at high latitudes.The UV monitoring at Denali will help scientists determine if there are changes in incoming ultraviolet radiation that may be affecting human health and ecosystem processes.
UV radiation was measured by a Brewer spectrophotometer located at park headquarters on the east side of Denali Park. This sophisticated instrument tracked the sun and monitored the variation in solar radiation throughout the day. It also recorded data on atmospheric ozone and gas concentrations that were then used to calculate the amount of UV at the surface of the earth.
Did You Know?
Warmer average temperatures over several decades have resulted in expansion of woody vegetation. If this warming trend continues, it will change Alaska's ecosystems and drastically alter the physical appearance of Denali's landscape, as treeline marches higher up the mountains.