In a paper published in the journal Icarus, researchers say the storm in late 2010 -- as large as any storm ever observed on the planet -- churned up water ice from great depths that was subsequently detected by near-infrared measurements by NASA's Cassini spacecraft.
"The new finding from Cassini shows that Saturn can dredge up material from more than 100 miles," said Kevin Baines, a co-author of the paper who works at the University of Wisconsin-Madison and NASA's Jet Propulsion Laboratory, Pasadena, Calif.
"It demonstrates in a very real sense that typically demure-looking Saturn can be just as explosive or even more so than typically stormy Jupiter."
Water ice, which originates from deep within the atmosphere of gas giant planets, doesn't appear to be lofted as high on Jupiter, the scientists said.
The classic model of Saturn's atmosphere posits a layered sandwich with a deck of water clouds at the bottom, ammonia hydrosulfide clouds in the middle, and ammonia clouds near the top.
But this storm appears to have disrupted those neat layers, the scientists said, lofting up water vapor from a lower layer that condensed and froze as it rose.
The Saturn storm worked like the much smaller convective storms on Earth, where air and water vapor are pushed high into the atmosphere resulting in the towering, billowing clouds of a thunderstorm, the scientists said.
"We think this huge thunderstorm [on Saturn] is driving these cloud particles upward, sort of like a volcano bringing up material from the depths and making it visible from outside the atmosphere," Lawrence Sromovsky, also of the University of Wisconsin, said.