ENSO Predictions with Coupled Ocean Atmosphere Models
ocean
uncoupled
ocean-atmosphere
coupled
initializalion
foreca t
--------~.~ ........... ..
t t t • t.· start of forecast
orced wlth o~s. wmhs
a: initialization with observed winds only
ocean
uncoupled
initialization
ocean-atmosphere
coupled
forecast
--------~.~~ ........... ..
arce tt .. • start of forecast
wit o~~. winrs
+ ocean data assimilation
'b: observed winds plus ocean data assimilation
ocean-atmosphere
coupled
ocean-atmosphere
coupled
initializa tion
forecast
---------I . . . ~ ........... ..
t t t t t l start of forecast
constrained, using
data assimilation
c: coupled initialization, constrained with observations
325
Fig. 16.11 Three different initialization methods for coupled general circulation models. In
the upper panel the conventional method is shown. Only observed wind fields are used to
initialize the model. In panel b additional information is obtained from oceanic observations.
In the lower panel the coupled system is initialized directly. Assimilation of oceanic or
atmospheric observations constrains the model.
called rigid lid approximation. That means that the sea surface height is a diagnostic variable. But even if no rigid Jid assumption is made it is not sensibJe to insert