Reston, Va. — A new, official height for Denali has been measured at 20,310 feet, just 10 feet less than the previous elevation of 20,320 feet which was established using 1950’s era technology. Advances in technology to better measure the elevation at the surface of the Earth resulted in a more accurate summit height of Alaska’s natural treasure.
Blaine Horner of CompassData probes the snow pack at the highest point in North America along with setting up GPS equipment for precise summit elevation data. Photo: Blaine Horner, CompassData
“No place draws more public attention to its exact elevation than the highest peak of a continent. Knowing the height of Denali is precisely 20,310 feet has important value to earth scientists, geographers, airplane pilots, mountaineers and the general public. It is inspiring to think we can measure this magnificent peak with such accuracy," said Suzette Kimball, USGS acting director. "This is a feeling everyone can share, whether you happen to be an armchair explorer or an experienced mountain climber.”
Denali National Park where the mountain is located, was established in 1917 and annually sees more than 500,000 visitors to the six million acres that now make up the park and preserve. About 1,200 mountaineers attempt to summit the mountain each year; typically about half are successful.
"Park rangers have been excited to work with and learn from their USGS colleagues using the latest technology to determine Denali's height,” said Denali NP Superintendent Don Striker. “Climbers and other visitors will be fascinated by this process, and I hope our future park rangers see from this firsthand example how a background in science, technology, engineering and mathematics, and staying physically active in the outdoors can enable them to do some of America's coolest jobs.”
To establish a more accurate summit height, the USGS partnered with NOAA’s National Geodetic Survey (NGS), Dewberry, CompassData, (a subcontractor to Dewberry) and the University of Alaska, Fairbanks, to conduct a precise Global Positioning System (GPS) measurement of a specific point at the mountain’s peak.
A previous 2013 Denali survey was called into question with an elevation measurement of 20,237 feet. That survey was done by an airborne radar measurement collected using an Interferometric Synthetic Aperture Radar (ifsar) sensor. Ifsar is an extremely effective tool for collecting map data in challenging areas such as Alaska, but it does not provide precise spot or point elevations, especially in very steep terrain.
The climbing team of GPS experts and mountaineers reached the Denali summit in mid-June. Since then, they have been processing, analyzing, and evaluating the raw data to arrive at the final number of 20, 310 feet. Unique circumstances and variables such as the depth of the snowpack and establishing the appropriate surface that coincides with mean sea level had to be taken into account before the new apex elevation could be determined.
A USGS feature story (http://www.usgs.gov/blogs/features/usgs_top_story/new-elevation-for-nations-highest-peak/?from=title) has more details about the trek, data collection and calculation methods.