HR: 0800h
AN: PP51E-0643    [Abstracts]
TI: Climate Changes Resulting From Removal of the Equatorial Cold Tongue Influence
AU: * Chiang, J C
EM: jchiang@atmos.berkeley.edu
AF: Dept of Geography, University of California, 547 McCone Hall, Berkeley, CA 94720-4740 United States
AU: Park, H
EM: hspark@atmos.berkeley.edu
AF: Dept of Geography, University of California, 547 McCone Hall, Berkeley, CA 94720-4740 United States
AB: We discuss salient global climate changes occurring in the Community Atmosphere Model version 3 (CAM3.0) resulting from removal of the equatorial cold tongue upwelling influence over the Pacific and Atlantic Oceans. This climate scenario may have occurred prior to the mid-Pleistocene transition before the advent of significant Northern Hemisphere glaciation; it also represents the extreme case a relaxation to the zonal gradient in tropical sea surface temperature ("permanent El Nino"). We achieve the 'no cold tongue' state by modifying the implied ocean heat transport in the eastern Pacific and tropical Atlantic applied to the slab ocean component of the model, to that resembling the Western Pacific and Indian Oceans where no significant equatorial upwelling occurs. Preliminary results indicate marked changes to the tropical convection and overturning circulations that lead to substantial teleconnected climate changes to the rest of the tropics and to the higher latitudes. In particular, surface temperatures rise (by up to 4-5 degrees C in some places) over northern North America and Europe during boreal winter and spring, and a cooling over the southern portions of North America. Sea ice cover is reduced over both hemispheres. The combined effect of the reduced upwelling and sea ice contributes to a global mean increase in surface temperature of over 1K. There is strengthening and slight equatorward shift of the surface westerlies over the Northern and Southern Pacific and Northern Atlantic oceans; and in the zonal mean, a strengthening of the subtropical/midlatitude jet over both hemispheres.
DE: 1620 Climate dynamics (0429, 3309)
DE: 3305 Climate change and variability (1616, 1635, 3309, 4215, 4513)
DE: 3339 Ocean/atmosphere interactions (0312, 4504)
SC: Paleoceanography and Paleoclimatology [PP]
MN: Fall Meeting 2005