Surprise Deep Ocean Eddies

Skip the larvae.  This is a brand new significant heat exchangemechanism that turns on and off at its pleasure.  When turned on a great deal of heat andnutrients are moved between the deep and the five hundred meter or so surface layerover the deep.  The transport of larvaeall over the place is a bonus.

All of a sudden, we need toconsider whether an extended period of eruption on the mid Atlantis ridge iscapable of inducing a significant temperature change in the Gulf stream.  By itself theanswer is no.  However if it triggered a newseries of giant eddies, the dynamics could actually arise.

Certainly, past warm spellsremain unexplained.  Something like thisis at least a plausible option.

Eddies found to be powerful modes of ocean transport

by Staff Writers

Woods Hole MA (SPX) Apr 29, 2011

Eddies appear to form repeatedly, and the high-speed, long-distancetransport can last for months.

http://www.terradaily.com/reports/Eddies_found_to_be_powerful_modes_of_ocean_transport_999.html

Researchers from Woods Hole Oceanographic Institution (WHOI)and their colleagues have discovered that massive, swirling ocean eddies-knownto be up to 500 kilometers across at the surface-can reach all the way to theocean bottom at mid-ocean ridges, some 2,500 meters deep, transporting tiny seacreatures, chemicals, and heat from hydrothermalvents over large distances.

The previously unknown deep-sea phenomenon, reported in the journalScience, helps explain how some larvae travel huge distances from one vent areato another, said Diane K. Adams, lead author at WHOI and now at the NationalInstitutes of Health.

"We knew these eddies existed," said Adams, a biologist."But nobody realized they can affect processes on the bottom of the ocean.Previous studies had looked at the upper ocean."

Using deep-sea moorings, current meters and sediment traps over asix-month period, along with computer models,Adams and her colleagues studied the eddies at the underwater mountain rangeknown as the East Pacific Rise.

That site experienced a well-documented eruption in 2006 that led to adiscovery reported last year that larvae from as far away as 350 km somehowtraveled that distance to settle in the aftermath of the eruption.

The newly discovered depth of the powerful eddies helps explain thatphenomenon but also opens up a host of other scientific possibilities in oceansaround the world.

"This atmospherically generated mechanism is affecting the deepsea and how larvae, chemical and heat are transported over largedistances," Adams said.

The eddies are generated at the surface by atmospheric events, such aswind jets, which can be strengthened during an El Nino, and "are known tohave a strong influence on surface ocean dynamics and production," sayAdams and Dennis J. McGillicuddy from WHOI, along with colleagues from FloridaState University, Lamont Doherty Earth Observatory,and the University of Brest in France. But this "atmospheric forcing...istypically not considered in studies of the deep sea," they report.

Moreover, the eddies appear to form seasonally, suggesting repeatedinteractions with undersea ridges such as the Eastern Pacific Rise. The models"predict a train of eddies across the ocean," Adamssaid.

"There may be two to three eddies per year at this location,"Adams said. Each one, she says, "couldconnect the site of the eruption to other sites hundreds of miles away."Elsewhere, she adds, "there are numerous places around the globe wherethey could be interacting with the deep sea."

In her 2010 report on larvae traveling great distances to settle at theeruption site, WHOI Senior Scientist Lauren S. Mullineaux , along with Adamsand others, suggested the larvae traveled along something like an underseasuperhighway, ocean-bottom "jets" travelling up to 10 centimeters asecond.

But conceding that even those would not be enough to carry the larvaeall that distance in such a short time, the researchers speculated that largeeddies may be propelling the migrating larvae even faster.

Adams's current work follows up on that possibility. "The mechanism wefound helps explain what we saw in the first paper," Adamssaid.

It is the larger picture, over longer periods of time, however, thatAdams and her colleagues find particularly intriguing. "Transport [ofocean products] could occur wherever...eddies interact with ridges-includingthe Mid-Atlantic Ridge,the Southwest Indian Ridge, and the East Scotia Ridge-and the surrounding deepocean," the researchers say.

And because the eddies appear to form repeatedly, the high-speed,long-distance transport can last for months. "Although the deep sea andhydrothermal vents in particular are often naively thought of as being isolatedfrom the surface ocean andatmosphere, the interaction of the surface-generated eddies with the deep seaoffers a conduit for seasonality and longer-period atmospheric phenomena toinfluence the 'seasonless' deep sea," Adams and her colleagues write.

"Thus, although hydrothermal sources of heat, chemical and larvalfluxes do not exhibit seasonality there is potential for long-distancetransport and dispersal to have seasonal to interannual variability."