The two goals of this chapter are to review the
current status of data-based analyses including
production of climatologies and atlases (Section
7.1.2), and to give an in-depth description (Section
7.1.4) of current progress in WOCE state estimation (data assimilation) related to regional and
global estimates of the ocean state. Progress with
ocean general circulation models is reviewed
briefly in Section 7.1.3, as modelling is a major
component of synthesis; Böning and Semtner
(Chapter 2.2) and Willebrand & Haidvogel
(Chapter 7.2) provide more complete reviews. We
give a tentative prediction of where WOCE synthesis activities will lead and especially what
progress can be expected from ocean state estimation over the next few years (Section 7.1.5).
7.1.2 Data-based analyses
Most observation-oriented research is being carried
out initially using observations in combination with
simple analytical or inverse models. The process of
data assembly and availability status are described
by Lindstrom and Legler (Chapter 3.5), as well as
in the WOCE AIMS plan (WOCE International
Project Office, 1997). Many of the data collection
and assembly efforts will continue past the end of
the WOCE AIMS phase and will provide a significant heritage for future organized programmes such
as CLIVAR (Climate Variability and Predictability)
or GOOS (Global Ocean Observing System). Links
to the WOCE data sets and a large amount of information about WOCE, as well as the WOCE bibliography, can be found at http://oceanic.cms.udel.edu/
woce. The ‘online’ data sources listed through the
rest of this text can be accessed at time of writing
through this central address.
Primary global WOCE data sources are hydrographic and velocity observations from research
ships including Conductivity-Temperature-Depth
(CTD) data, chemistry and Acoustic Doppler Current Profiler (ADCP) measurements, expendable
bathythermographs (XBTs) and XCTDs deployed
from merchant ships, subsurface floats, surface
drifters, and current meter arrays in restricted locations. With respect to ocean variability unprecedented information is being obtained from the
precise TOPEX/POSEIDON altimeter data set
(Fu, Chapter 3.3). The global data sets are being
combined to answer questions about large-scale
processes and to provide a basic description of the
ocean during the 1990s. A number of focused
regional process studies combined various observational techniques to tackle specific problems.
Where are we now with analysis of WOCE data
sets? How healthy is the synthesis phase given the
natural tendency for investigators to move on to
the next large programme? A more general question relates to the overall ‘success’ of the WOCE
observational programme – how appropriate and
well designed were the observational programmes?
Is there anything that we as a community would do
differently if the planning were to begin again, at
the same stage of technical development and computer power as was available in the mid-1980s?
The subsections here address the large-scale circulation, process experiments and variability studies.
Most of these topics are dealt with in much greater
detail in other chapters of this book. Inverse model
results are emphasized here because they are not
included separately elsewhere in the book.
7.1.2.1 Large-scale circulation and water mass
descriptions
Circulation and direct transport estimates relevant
to the long-time average ocean circulation are
derived from WOCE hydrographic observations
and average velocity fields from surface drifters
and subsurface floats. Results from many of the
WOCE hydrographic sections have been published, including water mass descriptions, transports and regional studies. Some of these results
are summarized in Section 4 of this book. This
work will continue over the next several years, and
forms one basis for the ongoing basin-oriented and
global work. Tracer analysis is approached initially on a more basin-wide scale than hydrography because the value tracers add to traditional
hydrographic analysis is an inventory of water
mass ages and ventilation paths, which are largerscale questions than are easily answered with individual sections. Current progress in using tracers is
described by Schlosser et al. (Chapter 5.8). These
are areas of continuing major activity for WOCE
investigators and are well represented in the large
WOCE bibliography.
Work on synthesizing the WOCE circulation
observations into basin-wide descriptions has also
begun. These take the form of property mapping
and merging of all available information to
produce the best estimate of circulation at all vertical levels, including both geostrophic calculations
SECTION 7 INSIGHTS FOR THE FUTURE
526
current status of data-based analyses including
production of climatologies and atlases (Section
7.1.2), and to give an in-depth description (Section
7.1.4) of current progress in WOCE state estimation (data assimilation) related to regional and
global estimates of the ocean state. Progress with
ocean general circulation models is reviewed
briefly in Section 7.1.3, as modelling is a major
component of synthesis; Böning and Semtner
(Chapter 2.2) and Willebrand & Haidvogel
(Chapter 7.2) provide more complete reviews. We
give a tentative prediction of where WOCE synthesis activities will lead and especially what
progress can be expected from ocean state estimation over the next few years (Section 7.1.5).
7.1.2 Data-based analyses
Most observation-oriented research is being carried
out initially using observations in combination with
simple analytical or inverse models. The process of
data assembly and availability status are described
by Lindstrom and Legler (Chapter 3.5), as well as
in the WOCE AIMS plan (WOCE International
Project Office, 1997). Many of the data collection
and assembly efforts will continue past the end of
the WOCE AIMS phase and will provide a significant heritage for future organized programmes such
as CLIVAR (Climate Variability and Predictability)
or GOOS (Global Ocean Observing System). Links
to the WOCE data sets and a large amount of information about WOCE, as well as the WOCE bibliography, can be found at http://oceanic.cms.udel.edu/
woce. The ‘online’ data sources listed through the
rest of this text can be accessed at time of writing
through this central address.
Primary global WOCE data sources are hydrographic and velocity observations from research
ships including Conductivity-Temperature-Depth
(CTD) data, chemistry and Acoustic Doppler Current Profiler (ADCP) measurements, expendable
bathythermographs (XBTs) and XCTDs deployed
from merchant ships, subsurface floats, surface
drifters, and current meter arrays in restricted locations. With respect to ocean variability unprecedented information is being obtained from the
precise TOPEX/POSEIDON altimeter data set
(Fu, Chapter 3.3). The global data sets are being
combined to answer questions about large-scale
processes and to provide a basic description of the
ocean during the 1990s. A number of focused
regional process studies combined various observational techniques to tackle specific problems.
Where are we now with analysis of WOCE data
sets? How healthy is the synthesis phase given the
natural tendency for investigators to move on to
the next large programme? A more general question relates to the overall ‘success’ of the WOCE
observational programme – how appropriate and
well designed were the observational programmes?
Is there anything that we as a community would do
differently if the planning were to begin again, at
the same stage of technical development and computer power as was available in the mid-1980s?
The subsections here address the large-scale circulation, process experiments and variability studies.
Most of these topics are dealt with in much greater
detail in other chapters of this book. Inverse model
results are emphasized here because they are not
included separately elsewhere in the book.
7.1.2.1 Large-scale circulation and water mass
descriptions
Circulation and direct transport estimates relevant
to the long-time average ocean circulation are
derived from WOCE hydrographic observations
and average velocity fields from surface drifters
and subsurface floats. Results from many of the
WOCE hydrographic sections have been published, including water mass descriptions, transports and regional studies. Some of these results
are summarized in Section 4 of this book. This
work will continue over the next several years, and
forms one basis for the ongoing basin-oriented and
global work. Tracer analysis is approached initially on a more basin-wide scale than hydrography because the value tracers add to traditional
hydrographic analysis is an inventory of water
mass ages and ventilation paths, which are largerscale questions than are easily answered with individual sections. Current progress in using tracers is
described by Schlosser et al. (Chapter 5.8). These
are areas of continuing major activity for WOCE
investigators and are well represented in the large
WOCE bibliography.
Work on synthesizing the WOCE circulation
observations into basin-wide descriptions has also
begun. These take the form of property mapping
and merging of all available information to
produce the best estimate of circulation at all vertical levels, including both geostrophic calculations
SECTION 7 INSIGHTS FOR THE FUTURE
526