Interdecadal interactions between the tropics and midlatitudes in the Pacific basin

PDF: http://data.dhkim.info/monograph/GRL/1999GL900042.pdf

GEOPHYSICAL RESEARCH LETTERS, VOL. 26, NO. 5, PAGES 615–618, 1999

Interdecadal interactions between the tropics and midlatitudes in the Pacific basin

Tim P. Barnett

Climate Research Division, Scripps Institution of Oceanography, La Jolla, California

David W. Pierce

Climate Research Division, Scripps Institution of Oceanography, La Jolla, California

Mojib Latif

Max Planck Institute for Meteorology, Hamburg, Germany

Dietmar Dommenget

Max Planck Institute for Meteorology, Hamburg, Germany

R. Saravanan

National Center for Atmospheric Research, Boulder, Colorado

Abstract

Analysis of global climate model simulations and observations suggest decadal, midlatitude changes in and over the North Pacific cause decadal modulation of the El Niño-Southern Oscillation. This coupling between the two geographic regions is via atmospheric, not oceanographic, teleconnections. In essence, large scale changes in the circulation of the atmosphere over the Pacific Basin, while largest in midlatitudes, have a significant projection onto the wind field overlying the equatorial regions. These low frequency wind changes precondition the mean state of the thermocline in the equatorial ocean to produce prolonged periods of enhanced or reduced ENSO activity. The midlatitude variability that drives equatorial impacts is of stochastic origin and, although the magnitude of the signal is enhanced by ocean processes, likely unpredictable. © 1999 American Geophysical Union

Index Terms: 3339 Meteorology and Atmospheric Dynamics: Ocean/atmosphere interactions (0312, 4504); 3309 Meteorology and Atmospheric Dynamics: Climatology (1620); 4203 Oceanography: