CORVALLIS, Ore. A new study published this week in the journal Nature reveals for the first time how the mixing of cold, deep waters from below can change sea surface temperatures on seasonal and longer timescales.
Because this occurs in a huge region of the ocean that takes up heat from the atmosphere, these changes can influence global climate patterns, particularly global warming.
Using a new measurement of mixing, Jim Moum and Jonathan Nash of the College of Earth, Ocean, and Atmospheric Sciences at Oregon State University have obtained the first multi-year records of mixing that permit assessment of seasonal changes. This is a significant advance beyond traditional shipboard measurements that are limited to the time that a ship can be away from port. Small instruments fueled by lithium batteries were built to be easily deployed on deep-sea equatorial moorings.
Moum employs a simple demonstration to show how mixing works.
He pours cold, white cream into a clear glass mug full of hot, black coffee, very carefully, using a straw to inject the heavier cream at the bottom of the mug, where it remains.
"Now we can wait until the cream diffuses into the coffee, and we'll have a nice cuppa joe," Moum says. "Unfortunately, the coffee will be cold by then. Or, we can introduce some external energy into the system, and mix it."
A stirring spoon reveals motions in the mug outlined by the black/white contrasts of cream in coffee until the contrast completely disappears, and the color achieves that of caf au lait.
"Mixing is obviously important in our normal lives, from the kitchen to the dispersal of pollutants in the atmosphere, reducing them to levels that are barely tolerable," he said.
The new study shows how mixing, at the same small scales that appear in your morning coffee, is critical to the ocean. It outlines the processes that create the equatorial Pacific cold tongue, a broad ex
|Contact: Jim Moum|
Oregon State University