312 Martin Fischer
JOH
15S
205
POP anolysis, real port of pseudo wind stress
25S
JOS L---~ I~~E--~IW~E~~IT.M~~I~W~W---I ~~=---~ l row~--7-'O~~~~M~W
POP onolysis, -i mog. po rt of pseudo wind stre ss
JOH
~N
,,~ ~ ~ ~ ~ ~ • • ~ - - ~ ,
~ •
~ -
, . .
~
~I"I'? . . . ·"11" \ 'II. •• "'!'-... . . . . . .
. ' -,' -
20N
I ~ .. , .. <1: , ~ , " , ~ . ? .. .. .. ~
.' ..... : -: . :
::
15N
,,.. ... II II II' ... .. i
"
\o , ,
•
.. .. •
II
•
j,.
~
c
..
. . .
I ~ .. ~ 1 , , I , <1 • , " ~ rI , rl II.,., . ........ , .
': ~~\j ' : .~ .~. ~I~~\\ t (i i ' ' \ţ ~:'i
.~."" I r,, ,{ +~
~ - . . ->' • < , 1 l , Il "
5S
. . . - . . : ~i .§ ?'~ ~-.. _" ~ " ..... Jf
~.
? .. ' . _ \ 0
I ( ( /' (/' ,. ... _ -... . . . . . . . . . .
10S
. ~
1(
t , \ "
" , \ { 1 Jf _ _ • ., .. • .. ., " > • 1\ ..
ISS
"
• \ \
. , \
'
I t ~ • • • • • • • .. • • • •
. • • •• 1'\,. \ \ \ \ • . • • • . • .
, . '
II" " ' t t ţ , f t , .. .. .. II[ '"
205
25S
. '
..... .. .. ,
.- '" 1" I , le •
mL---- ~ ~ E~-- IW ~E----I~M----I~row----,~~~W--~ 12~~~~IOO~W~~8~~
Fig. 16.4 Leading POP of a combined POP analysis of heat content anomalies, SST
anomalies, and wind stress anomalies. The NCEP ocean reanalysis and the FSU pseudo
wind stress data were used. Pseudo wind stress anomalies pattems are presented.
tance of the subsurface memory, as expressed by slow variations in the equatorial
Pacific upper ocean heat content, for the generation of ENSO has been shown in
many observational and model ing studies (e.g. Wyrtki 1985, Schopf and Suarez
1988, Latif et al. 1992).
One of the main characteristics of ENSO is its quasi-periodicity. ENSO can be
regarded as an eigenmode of the coupled ocean-atmosphere system, where the
memory of the system resides entirely in the ocean. To explain the quasi-periodic
nature of ENSO a conceptual model, the delayed aetion oseillator was proposed
by Schopf and Suarez (Schopf and Suarez 1988) which summarizes the fundamental zeroth-order physics involved in ENSO (Fig. 16.2). According to this model,
the easterly wind anomalies over the westem Pacific prevailing during the cold
phase (La Niiia) of the ENSO cycle generate an upwelling Kelvin wave packet
which propagates eastward along the equator. In the eastem Pacific, where the ther-
JOH
15S
205
POP anolysis, real port of pseudo wind stress
25S
JOS L---~ I~~E--~IW~E~~IT.M~~I~W~W---I ~~=---~ l row~--7-'O~~~~M~W
POP onolysis, -i mog. po rt of pseudo wind stre ss
JOH
~N
,,~ ~ ~ ~ ~ ~ • • ~ - - ~ ,
~ •
~ -
, . .
~
~I"I'? . . . ·"11" \ 'II. •• "'!'-... . . . . . .
. ' -,' -
20N
I ~ .. , .. <1: , ~ , " , ~ . ? .. .. .. ~
.' ..... : -: . :
::
15N
,,.. ... II II II' ... .. i
"
\o , ,
•
.. .. •
II
•
j,.
~
c
..
. . .
I ~ .. ~ 1 , , I , <1 • , " ~ rI , rl II.,., . ........ , .
': ~~\j ' : .~ .~. ~I~~\\ t (i i ' ' \ţ ~:'i
.~."" I r,, ,{ +~
~ - . . ->' • < , 1 l , Il "
5S
. . . - . . : ~i .§ ?'~ ~-.. _" ~ " ..... Jf
~.
? .. ' . _ \ 0
I ( ( /' (/' ,. ... _ -... . . . . . . . . . .
10S
. ~
1(
t , \ "
" , \ { 1 Jf _ _ • ., .. • .. ., " > • 1\ ..
ISS
"
• \ \
. , \
'
I t ~ • • • • • • • .. • • • •
. • • •• 1'\,. \ \ \ \ • . • • • . • .
, . '
II" " ' t t ţ , f t , .. .. .. II[ '"
205
25S
. '
..... .. .. ,
.- '" 1" I , le •
mL---- ~ ~ E~-- IW ~E----I~M----I~row----,~~~W--~ 12~~~~IOO~W~~8~~
Fig. 16.4 Leading POP of a combined POP analysis of heat content anomalies, SST
anomalies, and wind stress anomalies. The NCEP ocean reanalysis and the FSU pseudo
wind stress data were used. Pseudo wind stress anomalies pattems are presented.
tance of the subsurface memory, as expressed by slow variations in the equatorial
Pacific upper ocean heat content, for the generation of ENSO has been shown in
many observational and model ing studies (e.g. Wyrtki 1985, Schopf and Suarez
1988, Latif et al. 1992).
One of the main characteristics of ENSO is its quasi-periodicity. ENSO can be
regarded as an eigenmode of the coupled ocean-atmosphere system, where the
memory of the system resides entirely in the ocean. To explain the quasi-periodic
nature of ENSO a conceptual model, the delayed aetion oseillator was proposed
by Schopf and Suarez (Schopf and Suarez 1988) which summarizes the fundamental zeroth-order physics involved in ENSO (Fig. 16.2). According to this model,
the easterly wind anomalies over the westem Pacific prevailing during the cold
phase (La Niiia) of the ENSO cycle generate an upwelling Kelvin wave packet
which propagates eastward along the equator. In the eastem Pacific, where the ther-