Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Forming fogbows: Study finds limit on evaporation to ice sheets, but that may change

02.05.2016

Although the coastal regions of the Greenland Ice Sheet are experiencing rapid melting, a significant portion of the interior of that ice sheet has remained stable - but a new study suggests that stability may not continue.

Researchers found that very little of the snow and ice on the vast interior of the ice sheet is lost to the atmosphere through evaporation because of a strong thermal "lid" that essentially traps the moisture and returns it to the surface where it refreezes.


David Noone in a snow pit that reveals layers of snow that pile up one after another as different snow storms pass Summit Station, Greenland. Dark and light layering gives evidence of evaporation and refreezing of water vapor.

Credit: Oregon State University

However, there are signs that this lid is becoming leaky as global temperatures increase. The researchers say there may be a threshold at which warming becomes sufficient to turn on a switch that will destabilize the snow surface.

Results of the study, which was funded by the National Science Foundation, are being published in Science Advances. New measurements from a research tower atop the Greenland ice sheet helped uncovered the mystery of how much snow piles up on this ice sheet.

"Normally, the air temperature goes down as you climb, but near the surface in Greenland, it gets warmer," said David Noone, an Oregon State University professor who is an atmospheric scientist and principal investigator on the study. "The surface is very cold, but it can be as much as 20 degrees warmer just 30 to 40 feet up in the air. It's enough that you can feel the difference between your nose and your toes."

"The temperature difference effectively forms a lid so that there is hardly any evaporation. Warm air likes to rise, but if it is already warmer up above the air is trapped nearer the ground. One consequence is that layers of fog form from water that had recently evaporated. Eventually the small fog water-drops drift back down to the very cold surface where it refreezes onto the ice sheet."

"It's a handy little trick of nature."

Max Berkelhammer, a researcher at the University of Illinois and lead author on the study, said scientists have been aware of "accumulation zones" in high-altitude areas of the ice sheet, but they haven't been comprehensively measured because of the difficulty in analyzing evaporation and condensation over time.

"Instruments capable of doing this are pretty new and while they have been used before on the ice sheet, they have never been able to run during an entire winter," said Berkelhammer, who did his post-doctoral work with Noone when both were at the University of Colorado. "I think at this point we are still the only group who has been able to run this type of instrument for an entire year on top of an ice sheet."

The research aims to better understand how ice cores capture information about past temperatures in Greenland. The snow and ice on Greenland's interior originated from ocean water far to the south and is transported northward by weather systems and storms, and finally falls as snow on the pristine ice sheet.

The researchers are able to track the origins and fate of the water by the ratio of oxygen and hydrogen isotopes in the water.

Variations in the isotope ratios in layers of snow piled up on the ice sheet provide the team a history of Green climate that helps put recent warming into historical context, the researchers say.

To understand past climate, scientists must know how much precipitation fell and how much evaporated. Without the team's analysis, what fraction of falling snow accumulates and what fraction evaporates was difficult to determine. When they began to explore evaporation rates, they discovered this unique thermal lid, which effectively "recycles" water back onto the Greenland Ice Sheet.

This finding will allow previous estimates of Greenland's past water balance to be re-evaluated.

"When thinking about climate change, one often thinks about rising global temperatures," Noone said. "However in Greenland, as like here in Oregon, climate change is also a story of the changing water cycle and how we lose water because evaporation rates are increasing.

"Climate models suggest that as temperatures increase, more precipitation may actually fall in Greenland because warmer air can hold more water. Taken by itself, that could indicate that parts of the ice sheet may grow. However, if the lid becomes increasingly leaky, the evaporation process has become more effective and moisture will escape to the atmosphere.

"The fate of the ice sheet is in the balance," Noone said. "It becomes a question of which influence is stronger."

Media Contact

David Noone
dcn@coas.oregonstate.edu
541-737-3629

 @oregonstatenews

http://www.orst.edu 

David Noone | EurekAlert!

More articles from Earth Sciences:

nachricht Tracking down climate change with radar eyes
17.07.2019 | Technical University of Munich (TUM)

nachricht New sensor could shake up earthquake response efforts
11.07.2019 | DOE/Lawrence Berkeley National Laboratory

All articles from Earth Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Megakaryocytes act as „bouncers“ restraining cell migration in the bone marrow

Scientists at the University Würzburg and University Hospital of Würzburg found that megakaryocytes act as “bouncers” and thus modulate bone marrow niche properties and cell migration dynamics. The study was published in July in the Journal “Haematologica”.

Hematopoiesis is the process of forming blood cells, which occurs predominantly in the bone marrow. The bone marrow produces all types of blood cells: red...

Im Focus: Artificial neural network resolves puzzles from condensed matter physics: Which is the perfect quantum theory?

For some phenomena in quantum many-body physics several competing theories exist. But which of them describes a quantum phenomenon best? A team of researchers from the Technical University of Munich (TUM) and Harvard University in the United States has now successfully deployed artificial neural networks for image analysis of quantum systems.

Is that a dog or a cat? Such a classification is a prime example of machine learning: artificial neural networks can be trained to analyze images by looking...

Im Focus: Extremely hard yet metallically conductive: Bayreuth researchers develop novel material with high-tech prospects

An international research group led by scientists from the University of Bayreuth has produced a previously unknown material: Rhenium nitride pernitride. Thanks to combining properties that were previously considered incompatible, it looks set to become highly attractive for technological applications. Indeed, it is a super-hard metallic conductor that can withstand extremely high pressures like a diamond. A process now developed in Bayreuth opens up the possibility of producing rhenium nitride pernitride and other technologically interesting materials in sufficiently large quantity for their properties characterisation. The new findings are presented in "Nature Communications".

The possibility of finding a compound that was metallically conductive, super-hard, and ultra-incompressible was long considered unlikely in science. It was...

Im Focus: Modelling leads to the optimum size for platinum fuel cell catalysts: Activity of fuel cell catalysts doubled

An interdisciplinary research team at the Technical University of Munich (TUM) has built platinum nanoparticles for catalysis in fuel cells: The new size-optimized catalysts are twice as good as the best process commercially available today.

Fuel cells may well replace batteries as the power source for electric cars. They consume hydrogen, a gas which could be produced for example using surplus...

Im Focus: The secret of mushroom colors

Mushrooms: Darker fruiting bodies in cold climates

The fly agaric with its red hat is perhaps the most evocative of the diverse and variously colored mushroom species. Hitherto, the purpose of these colors was...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

2nd International Conference on UV LED Technologies & Applications – ICULTA 2020 | Call for Abstracts

24.06.2019 | Event News

SEMANTiCS 2019 brings together industry leaders and data scientists in Karlsruhe

29.04.2019 | Event News

Revered mathematicians and computer scientists converge with 200 young researchers in Heidelberg!

17.04.2019 | Event News

 
Latest News

Tracking down climate change with radar eyes

17.07.2019 | Earth Sciences

Researchers build transistor-like gate for quantum information processing -- with qudits

17.07.2019 | Information Technology

A new material for the battery of the future, made in UCLouvain

17.07.2019 | Materials Sciences

VideoLinks
Science & Research
Overview of more VideoLinks >>>