HR: 0800h
AN: PP31A-0906    [Abstracts]
TI: Can a freshwater forcing in high latitudes induce a permanent El Ni\~{n}o in the tropics - an overlooked mechanism for a rapid climate change.
AU: * Fedorov, A
EM: alexey.fedorov@yale.edu
AF: Yale University, Department of Geology and Geophysics, KGL, PO Box 208109, New Haven, CT 06520 United States
AU: Pacanowski, R
EM: ron.pacanowski@noaa.gov
AF: Geophysical Fluid Dynamics Laboratory, Route 1, Forrestal Campus, Princeton, NJ 08540 United States
AU: Philander, G
EM: gphlder@princeton.edu
AF: Princeton University, AOS Program, Sayre Hall, Forrestal Campus, Princeton, NJ 08540 United States
AU: Boccaletti, G
EM: gbocca@mit.edu
AF: MIT, Department of Earth, Atmospheric, and Planetary Sciences, 77 Massachusetts Avenue, Cambridge, 02139
AB: A rapid climate change in response to the current rise in the atmospheric concentration of greenhouse gases is a matter of considerable concern. Thus far attention has focused almost entirely on changes associated with the deep thermohaline circulation. Little attention has been paid to possible changes in the wind-driven circulation of the ventilated thermocline. This shallow wind-driven circulation controls a significant transport of heat from low to high latitudes and is therefore subject to the constraint of a balanced heat budget: on a certain time-scale, on the order of decades, the heat gain in the upwelling zones of low latitudes must equal the heat loss in high latitudes. Can a freshening of the surface waters in high latitudes significantly reduce this heat transport? How will that affect the tropics? To explore this matter we use a number of idealized general circulation models of varying complexity that capture the main aspects of the thermocline ventilation. Our calculations show that a freshening of the surface waters in high latitudes does reduce the poleward heat transport and deepens the tropical thermocline. For a sufficiently strong freshwater forcing, the poleward heat transport all but vanishes, and permanent El Ni\~{n}o-like conditions prevail in the tropics. Paleo data indicate that this have happened before - there was no equatorial SST gradient in the Pacific Ocean during the early Pliocene.
UR: http://www.geology.yale.edu/$\sim$avf5
DE: 3339 Ocean/atmosphere interactions (0312, 4504)
DE: 3344 Paleoclimatology
DE: 4267 Paleoceanography
DE: 4522 El Ni¤o
SC: Paleoceanography and Paleoclimatology [PP]
MN: 2004 AGU Fall Meeting