121
(a) JAN Initial Condition: SV = 3.06
6-Month Later: JUL
150E 180 150W 120W 90W
150E 180 150W 120W 90W
(b) APR Initial Condition: SV = 5.94
6-Month Later: OCT
150E 180 150W 120W 90W
150E 180 150W 120W 90W
(c) JUL Initial Condition: SV = 4.54
6-Month Later: JAN
1~:I:_~':::.-::_?: ___ . ____ 0~
EQ---:::--,_------------->
_
5S
---------'
\ ]
10SL-~ __ ~ __ ~~~_L _ _ ~D
150E 180 150W 120W 90W
150B 180 150W 120W 90W
(d) OCT Initial Condition: SV = 2.66
6-Month Later: APR
150E 180 150W 120W 90W
150B 180 150W 120W 90W
Figure 16: SST associated with dominant 6-month singular vector at initial (left) and
final (right) time, for a) January, b) April, c) July, d) October starts. The basic state
trajectory is a climatological annual cycle. From Chen et al (1996).
in particular) has no annual cycle. In fact, when the Battisti model is
run freely, the extrema of the model (NIN03) SST anomalies range from
over 2C in the warm phase to less than -IC in the cold phase. The solid
line in Fig 16 shows a timeseries of Nino 3 SST anomaly from year 9-