386
PIERRE BAHUREL
boundary conditions for regional models worldwide. This
configuration use the same parameterisation and physics than the
high resolution model describe upper and the improvements (free
surface, partial step vertical coordinate, atmospheric bulk formulae
and sea ice model) will be implemented .
Two lighter configurations are also implemented in real-time by
MERCATOR for demonstration and testing of new algorithms:
x
A middle resolution basin configuration developed during the
clipper project [Treguier et al., 2001] (1/3° horizontal resolution, 43
vertical levels from 12 m at the surface to 200 m at the bottom )
covering North and Tropical Atlantic.
x
A low resolution global configuration (2° horizontal resolution, 30
vertical levels) covering global ocean [Madec and Imbard, 1996].
In September 2004, the two basin configurations (middle and high
resolution) as well as the low resolution global ocean one are operational;
the ¼° global ocean model is under development and will integrate the
operational chain in the coming months.
2.3
Assimilation method
An ocean monitoring and forecasting system is based on two integrated
components: the remotely sensed (e.g. SST, altimetric data) and in situ (e.g.
temperature and salinity profiles) observations and the thermodynamical
ocean model that are combined to give the best possible description of the
real ocean. The way to optimally combine the information given by each
system component is called “data assimilation”. This optimal combination
(i.e. data assimilation) is achieved by taking advantage both from the
information contained in the observations of the real ocean and from the
constraints imposed by the ocean model physics. Data assimilation allows
for instance eddy permitting ocean models to have meso-scale structures that
are in phase with what can be observed and to provide a description of the
ocean closer to the reality.
MERCATOR assimilation deals with altimeter sea level anomaly, sea
surface temperature and temperature and salinity in situ profiles data into its
basin and global scale models. Assimilation is considered for routine nearreal-time nowcasts and forecasts issues, but also long term reanalysis
products.
MERCATOR is developing a suite of assimilation tools (called SAM
for MERCATOR Assimilation System) of increasing complexity, from
sequential to variational method: the first release, SAM-1, is based on
optimal interpolation ; the second release, SAM-2, will consider a Singular
Extended Evolutive Kalman (SEEK) filtering analysis method ; and the third
“
”
PIERRE BAHUREL
boundary conditions for regional models worldwide. This
configuration use the same parameterisation and physics than the
high resolution model describe upper and the improvements (free
surface, partial step vertical coordinate, atmospheric bulk formulae
and sea ice model) will be implemented .
Two lighter configurations are also implemented in real-time by
MERCATOR for demonstration and testing of new algorithms:
x
A middle resolution basin configuration developed during the
clipper project [Treguier et al., 2001] (1/3° horizontal resolution, 43
vertical levels from 12 m at the surface to 200 m at the bottom )
covering North and Tropical Atlantic.
x
A low resolution global configuration (2° horizontal resolution, 30
vertical levels) covering global ocean [Madec and Imbard, 1996].
In September 2004, the two basin configurations (middle and high
resolution) as well as the low resolution global ocean one are operational;
the ¼° global ocean model is under development and will integrate the
operational chain in the coming months.
2.3
Assimilation method
An ocean monitoring and forecasting system is based on two integrated
components: the remotely sensed (e.g. SST, altimetric data) and in situ (e.g.
temperature and salinity profiles) observations and the thermodynamical
ocean model that are combined to give the best possible description of the
real ocean. The way to optimally combine the information given by each
system component is called “data assimilation”. This optimal combination
(i.e. data assimilation) is achieved by taking advantage both from the
information contained in the observations of the real ocean and from the
constraints imposed by the ocean model physics. Data assimilation allows
for instance eddy permitting ocean models to have meso-scale structures that
are in phase with what can be observed and to provide a description of the
ocean closer to the reality.
MERCATOR assimilation deals with altimeter sea level anomaly, sea
surface temperature and temperature and salinity in situ profiles data into its
basin and global scale models. Assimilation is considered for routine nearreal-time nowcasts and forecasts issues, but also long term reanalysis
products.
MERCATOR is developing a suite of assimilation tools (called SAM
for MERCATOR Assimilation System) of increasing complexity, from
sequential to variational method: the first release, SAM-1, is based on
optimal interpolation ; the second release, SAM-2, will consider a Singular
Extended Evolutive Kalman (SEEK) filtering analysis method ; and the third
“
”