New research suggests that the snowiest winters on the East Coast are fueled by moisture being pumped out of the Arctic Ocean.
The study, which drew on more than 40 years of water samples taken at the Hubbard Brook Experimental Forest in New Hampshire, found that much of the precipitation in snowy years in that New Hampshire forest, originated in the Arctic.
“Water that comes from the Arctic Ocean is going to have a different isotopic value than the water that comes from the Southern Atlantic,” says Myron Mitchell, a researcher in environmental science and forestry and a co-author of the study. “These differences don't affect the chemistry of water, but they actually can be used as a tracer, giving us information of where the water comes from ... It's not a completely simple story, but it does give us some idea.”
The two major elements in water are hydrogen and oxygen, but it's not so simple. There are different kinds of hydrogen and oxygen, called isotopes. To a certain degree, the different isotopes that make up the hydrogen and oxygen in water can indicate where that water has been, Mitchell says.
The findings are significant as they relate to increased evaporation in areas where ocean water is warming, like in the Arctic. Evaporation results in a slight variation between a lighter isotope and a heavier isotope, Mitchell explains.
“Let’s say you have some water sitting in a container, and you warm that water,” Mitchell explains. “The water that comes off that container is evaporated, and the evaporated water has a little lighter isotopes than the water which remains within the container.”
The same process applies in the Arctic. As the Arctic Ocean temperature increases, more of that water evaporates into the atmosphere. It warms the atmosphere and alters the weather patterns that carry precipitation.
“As it changes the weather patterns, we can see that the water that comes from the vortex is affecting the precipitation amounts in the northeastern United States,” Mitchell says.
The measurements from the Hubbard Brook Experimental Forest lend scientific heft to these findings and help to confirm earlier findings about the effect of melting Arctic sea ice. Measurements in Hubbard began in the 1950s and the forest has developed a long-term record of providing data on environmental change, Mitchell says.
“It was one of the first places in the United States in which acid rain was determined,” he notes. “It's particularly unique in that, not only have samples been collected for long periods of time at Hubbard Brook, but these samples have also been stored in an archive so people can look at these samples and use them for helping to understand how things have changed over time.”
Mitchell says their isotope measurements correspond well with a mathematical model developed at the National Oceanic and Atmospheric Administration, called back trajectory modeling, which also tries to determine where water originated.