intensity. Many indices have been defined to describe
the intensity character of the EAT, and a lot of meaningful
results were obtained. For example, Qiu and
Wang (1984) noted that the outbreak of the EAWM
and subsequent drop of temperature over East Asia is
closely related to the deepening of the EAT. Li (1988,
1990) suggested that the deepening of the EAT is a
triggering mechanism for the consequent tropical convective
activities and the El Nin˜o events. Cui and Sun
(1999) proposed an EAWM index based on the intensity
of the EAT in view of the close relationship
between the EAWM and the EAT. However, little attention
has been paid to other characteristics of the
EAT, particularly the position or the tilt of its axis