Figure 13 exhibits the composite difference of SST
anomalies between high and low TAI phases. The most
dominant feature in the simultaneous composite is the
positive SST anomalies in North Pacific and negative
anomalies along the southeast coast of the Eurasian
continent and in the tropical central and eastern Pacific
(Fig. 13b). The lead/lag composite of SST was then
calculated as a check of possible oceanic influences on
the atmosphere. Although there are SST anomalies in
the tropical eastern Pacific, both the pattern and evolution
of SST anomalies as shown in Fig. 13 do not
resemble those associated with ENSO (e.g., Chen
2002). In-depth analysis finds that the tropical SST
anomalies are not symmetry for high and low TAI
years (figures not shown). On the contrary, almost
symmetry SST signals exist in the North Pacific for
high and low TAI years. Moreover, significant SST
anomalies in the North Pacific can be traced back to
the preceding autumn (Fig. 13a) and last until the
following summer (Figs. 13c,d). In fact, the significant
anomalies in the North Pacific can be traced back to
the preceding summer, that is, for a time lag of two
seasons. This can be clearly seen from the lag correlations
between the TAI and the averaged SST
anomalies in the North Pacific region (358;458N and
1608E;1708W, Fig. 14). The SST anomalies have been
smoothed by three-month running means before calculating
the lag correlation in order to deduce the relationships
for seasonal means. The result implies a
dominant influence of North Pacific SST anomalies on
the wintertime tilt of the EAT. In addition, enhanced
oceanic response in winter and the following spring
suggests possible atmospheric forcing on the ocean.
Hence, the interannual variations of the tilt of the
EAT is suggested to be possibly caused by the