HR: 1300h
AN: OS52D-08    [PDF]
TI: Sensitivity of the Equatorial Cold Tongue and ENSO to the Tropical Pacific Meridional Wind Stress Climatology
AU: * Wittenberg, A T
EM: Andrew.Wittenberg@noaa.gov
AF: Princeton University, Atmospheric \& Oceanic Sciences Program, Sayre Hall, Forrestal Campus, Princeton, NJ 08544-0710 United States
AU: Philander, S H
EM: gphlder@princeton.edu
AF: Princeton University, Atmospheric \& Oceanic Sciences Program, Sayre Hall, Forrestal Campus, Princeton, NJ 08544-0710 United States
AB: The southeastern equatorial Pacific trade winds have a strong southerly component, which drives oceanic upwelling south of the equator and contributes to the intensity and meridional asymmetry of the equatorial cold tongue. Here we investigate how the climatological meridional wind stress ($\overline{\tau}_y$) controls tropical Pacific climate and ENSO behavior, through coupled model experiments in which this stress component is artificially weakened or strengthened. For weak $\overline{\tau}_y$, the climatological cold tongue is weak and detached from the Peru coast, and ENSO variability is highly damped. Increasing $\overline{\tau}_y$ intensifies the cold tongue, enhances the meridional climate asymmetry, and destabilizes ENSO. Analysis of the oceanic mixed layer thermodynamics reveals how $\overline{\tau}_y$ alters the zonal advective and thermocline feedbacks that govern the stability and period of El~Ni\~{n}o, by controlling the background state upon which it evolves. The results shed light on some tropical Pacific biases common among coupled general circulation models.
UR: http://www.gfdl.noaa.gov/$\sim$atw/research/conf/ocean12
DE: 3339 Ocean/atmosphere interactions (0312, 4504)
DE: 4215 Climate and interannual variability (3309)
DE: 4231 Equatorial oceanography
DE: 4504 Air/sea interactions (0312)
DE: 4522 El Ni¤o
SC: Ocean Sciences [OS]
MN: 2004 Ocean Sciences Meeting