History of the Sierra Snow Lab
April 15, 2009
Editor’s note: This is the second in a two-part series. To read the first entry, search McLaughlin.
The Sierra Nevada snowpack is California’s most valuable natural resource. When all that frozen precipitation melts it supplies more than half of the Golden State’s total water supply. The first attempts to study this vital, complicated resource got underway right here in the Lake Tahoe-Donner Summit region.
The earliest studies of California’s vital mountain snowpack began with Dr. James E. Church, who is well known for his pioneering work in the science of snow surveying during the early 20th century. In 1905, he established the first Sierra weather observatory atop 10,776-foot-high Mt. Rose (southwest of Reno) and then later developed procedures for measuring the depth of snow and its water equivalent.
Dr. Church made many important contributions to snow and water management and he is deservedly revered as the “Father of Snow Surveying”. A major advance came in 1945 when U.S. Weather Bureau physicist Dr. Robert W. Gerdel was directed to build the Central Sierra Snow Research Laboratory at Soda Springs.
Among the many significant achievements made at the Soda Springs lab, in 1948 Gerdel and B. Lyle Hansen developed the first nuclear snow gage, which used radioactive material to measure snowpack water content. Hansen was director of the lab and a whiz at designing cutting-edge instruments like the radioisotope snow profiler.
Gerdel and Hansen took a small capsule of radioactive Cobalt 60 to a remote location, placed the material at ground level with a Geiger counter suspended by a cross arm 15 feet above. As the gamma rays passed through the snowpack, collisions with water molecules lowered their energy level, which indicated the amount of water in the snow. The Geiger counters were rigged with radio-transmitters so measurements could be relayed in real-time to the snow lab. Ultimately off-site hydrologists in Sacramento or San Francisco could also receive the signals.
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This radio-transmitted system was the first step in establishing an array of remote sensors in the Sierra snowpack, an important breakthrough in snow surveying. The idea of using nuclear material to remotely measure snowpack density was brilliant and scientists have substantially improved the technology. The ability to repeatedly measure the same vertical section of snow provides real-time information on rain-on-snow events that can lead to serious flooding.
Dr. Gerdel was Technical Supervisor at the Central Sierra Snow Lab from 1945 until 1950, at which time he was reassigned to a new government agency known as SIPRE, the Snow, Ice and Permafrost Research Establishment. Gerdel would later find himself working at Camp Century, a secret nuclear-powered city that housed 200 personnel under the Greenland Ice Cap. It would also be at Camp Century where Gerdel’s colleague B. Lyle Hansen would invent a heated drill bit to extract ice cores that retained physical evidence from previous global climate regimes, a major breakthrough in paleoclimatology, but that is a story for another day.
In the decades since Gerdel’s team developed the first snow gage that could relay real time measurements via radio waves, scientists have come up with more durable, accurate and sophisticated instruments. During the 1960s, the development of automatic sensors for obtaining snowpack water content from remote areas grew rapidly. Pressure pillows (snow pillows) were installed at various locations in the Sierra. Snow pillows are large vinyl bladders filled with a mixture of alcohol and water that are placed on the ground and protected from wild animals by wire mesh. The pillow is basically a hydraulic weighing platform that determines water content by recording the weight of the snowpack.
In the mid 1970s, scientists incorporated meteor burst telemetry technology to relay information from the snow pillows that were usually located at inaccessible, high elevation sites. It’s an ingenious system that relays radio signals long distances by bouncing them off the ionized gas trails of meteor dust in the upper atmosphere. This technique allows real-time data transmission between a remote sensor site and a collection station up to 1,200 miles away.
This survey system called SNOTEL (for SNOwpack TELemetry) revolutionized data collection by giving hydrologists daily measurements from a network of more than 600 SNOTEL sites throughout the West. The remote stations rely on solar power and batteries, and the system can accommodate a variety of sensors, including wind speed, relative humidity, and temperature.
In the 1990s, the Central Sierra Snow Lab began replacing its snow pillows, which became erratic and occasionally got disturbed by curious bears with more accurate gamma-ray detectors. It’s a high-tech, but straightforward technology where sensors are designed to detect these rays, which bombard the Earth constantly as a product of the cosmic energy of deep space. It works because water absorbs gamma radiation at the same rate whether it is in its liquid or frozen phase. Sensors are placed on the ground and on towers. As snow piles up, it can measure the difference and determine the water content of the snowpack.
The latest tool being utilized to improve snowpack and snowmelt runoff forecasts incorporates satellite technology. The use of satellites to augment snow surveys and telemetry stations is more limited in the western U.S. because the best results occur in flat open terrain with minimal vegetation. In the future, satellites will likely play a greater role in runoff forecasts, but at this time using this technology is expensive and still in the experimental stages.
The winter snow surveys provide crucial information for successfully managing our extensive reservoir and irrigation systems. In addition to providing reliable conditions for studying the physics of a deep snowpack, research conducted at the Central Sierra Snow Lab was critically important to developing flood control projects and the effective management of California’s water supplies. Over the years, water users and voters have invested more than $50 billion (in 2007 dollars) for a coordinated statewide water system.
The research performed at the Soda Springs lab has enabled hydrologists to closely monitor snowfall and snow melt, information that helped establish California’s State Water Project and the federal Central Valley Project. Together, these large-scale water transfer projects provide Sacramento River Delta water to 25 million Californians and irrigate millions of acres of farmland. They also directly support more than $400 billion of California’s economy.
In the late 1990s, budget cuts forced the Forest Service to close down the lab, but fortunately the University of California came to the rescue. Today (2009) the Central Sierra Snow Lab is managed by Randall Osterhuber. The University of California, Berkeley operates the lab under an agreement with the U.S. Dept. of Agriculture, the Forest Service, and in cooperation with the California Dept. of Water Resources. To learn more or to schedule a visit to the lab, contact Randall Osterhuber at: http://research.chance.berkeley.edu/cssl/
Pioneering efforts by Dr. Church, Dr. Gerdel, and others to investigate and improve our scientific understanding of the complexities of the vital Sierra snowpack have laid the groundwork for an extensive snowpack and water management system that has helped nourish and sustain California’s growth into an economic giant. The threat of climate change and its inherent challenges to the state’s extensive water system make this work more important than ever.
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