Interdecadal changes in eastern Pacific ITCZ variability
and its influence on the
Atlantic ITCZ
Abstract
The eastern Pacific and Atlantic Intertropical Convergence Zones
(ITCZ) exhibit the largest year-to-year variations in boreal spring.
We show evidence suggesting that Atlantic ITCZ April-May variability
is linked to that for the eastern Pacific through the Walker
circulation as it respond to changes in equatorial Pacific
convection. Analysis of ITCZ proxy indices shows the link appears
to be strong in the 1980-90's and 1920-30's but virtually
nonexistent in the 1950-60's. We argue that this apparent
nonstationarity results from the nonlinear relationship between sea
surface temperature (SST) and convection in the eastern equatorial
Pacific and its consequent effect on the Walker circulation and the
Atlantic ITCZ. This mechanism was modulated over 1856-1998 by
interdecadal changes in peak SST attained in the eastern equatorial
Pacific during boreal spring.
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