U OF S RESEARCHERS MEASURE EVAPORATION OF GLACIAL SNOW
By Lawrence McMahen
Braving thin air, scorching sunlight, glacial ice and steep mountain terrain, two U of S researchers recently carried computerized sensors high into the South American Andes in a scientific ‘first’.
Geography professor and Canada Research Chair (CRC) John Pomeroy and Research Officer Michael Solohub, along with colleagues from France’s Development Research Institute (IRD), hiked up to the 16,900-ft. (5,150 m) surface of Bolivia’s Zongo Glacier in August, placing U of S instruments to gauge the evaporation of snow and ice. The site is well up the slopes of Mt. Huayna Potosi.
“It’s the highest altitude on Earth at which such instruments have been installed. They have provided the first direct measurements of the flow of water vapour from tropical high-altitude glaciers,” Pomeroy says.
He adds that because of their dry atmosphere, strong winds and intense sunlight, glaciers in places like South America and Africa are quickly evaporating.
“African glaciers on mountains like Kilimanjaro will be gone within a few decades. Glaciers in many parts of the tropics are retreating rapidly and many are anticipated to disappear in the next few decades,” Pomeroy says.
The loss of slowly melting snowpacks that persist into the dry season on glaciers will mean a major shift in the timing of water availability in the impoverished, arid highlands of South America and similar areas around the world.
“Currently, snowmelt on glaciers in the dry season provides important streamflow for hydroelectric generation, urban water consumption and rural irrigation,” Pomeroy says.
He adds that his Bolivian studies will shed light on similar, but slower, loss of snow and glacier reserves in Canada.
He, along with Solohub, their French colleagues, and local porters drove the computer-operated “ultrasonic anemometer” and support equipment up rocky, rubble-strewn Andean roads to the mountainous 14,700-ft. (4,500 m) level, 40 km from the Bolivian capital of La Paz, then hiked it up the final 2,000 feet. In the thin air, “it wasn’t always fun, but the scenery was always great”.
The equipment was set on the glacier and readied to measure wind speed, air temperature, relative humidity and other factors assessing ice and snow “sublimation”, or evaporation.
Pomeroy says it was left in place for three weeks, then retrieved. Data analysis started on laptop computers in a mountain refugio, or hut, near the glacier where the scientists stayed in the evenings. Pomeroy and colleagues are already writing scientific papers based on the data, and he’ll present on it at an American Geophysical Union conference in San Francisco in December.
Pomeroy, Solohub and colleagues from the U of S and Environment Canada’s National Hydrology Research Centre at Innovation Place have placed similar measuring instruments in Saskatchewan, the Northwest Territories and the Yukon.
“Last week we started at a new location in the Kananaskis Valley (in Alberta),” which will help to measure loss of moisture from a key source of water for Saskatchewan’s river systems, Pomeroy says.
He says a number of graduate students are working on the project, and it has important implications for agriculture and urban water supplies, and for the impact of climate change on water resources.
Pomeroy earned his degrees in geography and agricultural engineering from the U of S more than 20 years ago. He was recruited to his CRC post in 2003 from a position at the University of Wales. He is CRC in Water Resources and Climate Change.
He says the University now has the largest concentration of hydrology researchers at any academic institution in the country – and combined with scientists from the Environment Canada labs at Innovation Place, “this makes Saskatoon ‘Canada’s hydrology capital’.”