Summary: would be expected in a chaotic system but
instead converge to nearly identical values.
There are several models (8, 9) that have
successfully simulated the observed seasonal
mean tropical rainfall with prescribed SST.
This apparent lack of sensitive dependence
on the initial conditions provides a scientific
basis for long-range forecasting of tropical
climate variations. As shown by several mod-
eling and theoretical studies (1013), reliable
probabilistic estimates of extratropical pre-
dictability are also realizable but only in the
case of large tropical SST anomalies.
There is not yet a rigorous explanation for
why the tropical atmosphere has such a
unique property. However, it is reasonable to
conjecture that the latitudinal dependence of
the rotational force and solar heating produce
the unique structure of the large-scale tropical
motion field that, for a given boundary con-