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SYLVIE POULIQUEN
2.2
Timeliness
What does real time mean for operational oceanography? The main
criterion is to define the delay between measurements and assimilation
beyond which the measurement adds nothing to the performance of the
model. There is no unique answer: this depends on the type of models, the
variables that are assimilated, the forecast product and the application for
which it is produced. For instance, assimilated information of deep ocean
temperature and salinity will persist within an ocean global circulation
model for weeks or months and so a delay of several days in supplying data
can be acceptable. On the other hand, oceans mixed layers vary on more
rapid timescales in response to the diurnal heating and to storms. The impact
of such data will probably not persist more than 3-5 days after assimilation,
so measurements are needed within a day. As a compromise, real time for
operational oceanography generally means availability within 1 or 2 days
from acquisition, to allow data centres to better qualify the data even if it
takes a bit more time. For climate applications larger delays are acceptable,
but the length of the observation period is critical.
2.3
Agreed procedures and standards
Operational models use a wide variety of data from a diverse sources
including buoys, drifters, ARGO floats, regional ships of opportunity,
coastal observatories and even isolated local measurements made either by
nations or scientists, as long as the data are easily available and qualitycontrolled in a timely way. Sea observations are very expensive and no
country is able to sustain alone, the network needed by operational
oceanography at the global level. Moreover it is important to design a
system able to serve different communities: e.g. research, climate and
operational communities. Therefore, an international coordination is needed.
In 1950, the meteorological community has set up an organisation WMO
(World Meteorological Organisation) to organize this partnership for the
meteorological needs. Under the auspice of Unesco, IOC( Intergovernmental
Oceanographic Commission) has played an essential role in defining
measurement standards and formats. The JCOMM (Joint WMO/IOC
commission for operational oceanography and marine meteorology) has
been set up to strengthen the role of WMO and IOC in the field of ocean and
marine meteorology. It is involved in the main observing systems used
nowadays by operational models:
¾ Surface data: DBCP (Drifters), VOS (Voluntary Observing ships),
SYLVIE POULIQUEN
2.2
Timeliness
What does real time mean for operational oceanography? The main
criterion is to define the delay between measurements and assimilation
beyond which the measurement adds nothing to the performance of the
model. There is no unique answer: this depends on the type of models, the
variables that are assimilated, the forecast product and the application for
which it is produced. For instance, assimilated information of deep ocean
temperature and salinity will persist within an ocean global circulation
model for weeks or months and so a delay of several days in supplying data
can be acceptable. On the other hand, oceans mixed layers vary on more
rapid timescales in response to the diurnal heating and to storms. The impact
of such data will probably not persist more than 3-5 days after assimilation,
so measurements are needed within a day. As a compromise, real time for
operational oceanography generally means availability within 1 or 2 days
from acquisition, to allow data centres to better qualify the data even if it
takes a bit more time. For climate applications larger delays are acceptable,
but the length of the observation period is critical.
2.3
Agreed procedures and standards
Operational models use a wide variety of data from a diverse sources
including buoys, drifters, ARGO floats, regional ships of opportunity,
coastal observatories and even isolated local measurements made either by
nations or scientists, as long as the data are easily available and qualitycontrolled in a timely way. Sea observations are very expensive and no
country is able to sustain alone, the network needed by operational
oceanography at the global level. Moreover it is important to design a
system able to serve different communities: e.g. research, climate and
operational communities. Therefore, an international coordination is needed.
In 1950, the meteorological community has set up an organisation WMO
(World Meteorological Organisation) to organize this partnership for the
meteorological needs. Under the auspice of Unesco, IOC( Intergovernmental
Oceanographic Commission) has played an essential role in defining
measurement standards and formats. The JCOMM (Joint WMO/IOC
commission for operational oceanography and marine meteorology) has
been set up to strengthen the role of WMO and IOC in the field of ocean and
marine meteorology. It is involved in the main observing systems used
nowadays by operational models:
¾ Surface data: DBCP (Drifters), VOS (Voluntary Observing ships),