Percolation Models Reveal Ice Dynamics

Ken Golden is one of the people who are able to look at something around them and instantly find correlations with something else. Fortunately, he did that in 1994, when the University of Utah mathematician partook in the Antarctic Zone Flux Experiment, which took place on the shores of the Eastern Weddell Sea. There, he noticed that the way in which sea water flooded the ice sheets and created the frozen slur that was snow-ice was similar to the mathematical concept of percolation.

This concept refers to an area of mathematics involved with studying how fluids move and interact with porous materials. So, it stands to reason that his observations on how the slushy material, made up of ice and sea water, infiltrated the ice sheet beneath, and then either returned to the water, or froze over, were actually founded on a solid scientific background.

In this month's upcoming issue of the journal Notices of the American Mathematical Society, Golden and some of his co-workers will detail how their mathematics apply to climate change and to configuring new models for the evolution of ice in the Antarctic.

During his expedition to the South Pole, the expert noticed that sea ice was impermeable by the briny solution that was created on its surface when sea water got in. Still, at one point, it gave way, and allowed the fluid to pass through it.

The researcher then understood that the secret was the concentration of salt in the water above the ice. If salts were present in a proportion less than five percent, then the briny fluid could not get through the ice. Add more salt, and the ice suddenly becomes more permeable. “It was just a cool observation, with the comparison to stealthy materials. I didn't realize how important it was at the time,” he recently said.

Although it may not seem like much, Golden's discovery was one of major implications. The flow of water above the Antarctic ice is of paramount importance in determining exactly how many lakes are formed over the ice, and how sunlight influences these lakes and the ice underneath. Because of liquid water, the light bounces off differently from the ice, which can cause temperature fluctuations. These may influence the flow of icebergs to the sea, as well as other such events. So, as it later turned out, his find was one that allowed for ulterior computer models of how Antarctica would change over the years.