when they cycle to the surface. WOCE’s contribution to upper ocean thermal data sets has been
three-fold: collection of XBT data; development of
the profiling float; and provision of the framework
for quality control and archiving of the datasets.
In these efforts, only the high-resolution XBT programme (closely spaced profiles along selected
seasonally repeated merchant ship transects) was
entirely a WOCE programme; all other XBT work
has been joint with other climate programmes, such
as Tropical Ocean Global Atmosphere (TOGA),
which recognize the importance of regular thermal
sampling in the upper ocean for climate studies.
Float work and especially technical development
was also supported by other programmes in addition to WOCE, although the primary impetus and
much of the funding came from WOCE.
The thermal data are used as inputs to developing coupled prediction models. The Global Temperature–Salinity Pilot Project (GTSPP), run by the
National Oceanographic Data Center (NODC) in
the US, is the central resource for this programme
at this time. After collection of XBT data at
NODC, data are quality-controlled by three data
assembly centres: the US’s Scripps Institution of
Oceanography (SIO) (Pacific Ocean), Australia’s
Commonwealth Scientific and Industrial Research
Organization (Indian Ocean), and the US’s NOAA
Atlantic Oceanographic and Meteorological Laboratory (Atlantic Ocean). Data are available online
from the NODC. Profiling float data, for which
collection began around 1995, are still in an experimental stage, particularly with regard to archiving;
at this time only the temperature profiles are sent
to NODC.
Climatologies, including monthly averages of
temperature, heat storage and mixed-layer depth
fields and anomalies, have been produced by the
Joint Environmental Data Analysis Center (JEDAC)
at SIO (White, 1995) and are easily accessible
online at SIO and through the World Meteorological Organisation/Intergovernmental Oceanographic Commission site at Lamont-Doherty Earth
Observatory. Analyses for the Indian Ocean are
available online from CSIRO in Australia. The
fields are used for basic research and comparison
with models (e.g. Auad et al., 1998).
Velocity data sets
Velocities are measured directly in three ways in
WOCE: current meters at fixed sites, Lagrangian
drifters and floats, and acoustic Doppler current
profiling. Current meter records, including means
and statistics, constitute a type of climatology,
albeit based only on the time period of each current meter record. Pre-WOCE (pre-1989) current
meter statistics were compiled by Dickson (1990),
with an update from the WOCE period compiled
by Dickson, Medler and Wooltorton; both are
available online through the WOCE Current
Meter Data Assembly Centre (CMDAC). The
CMDAC also maintains statistics for WOCE
current meters.
WOCE provided a major expansion of subsurface float coverage compared with the limited
deployments prior to WOCE and critical breakthroughs in float technology with the aim of
global coverage. Many of the subsurface floats at
mid-depth deployed in WOCE are still functioning
and data are still being recorded. The next few
years will see continuation and expansion of the
WOCE profiling float coverage (the Argo programme), largely for the temperature (and salinity)
profiling capabilities of the floats, as part of international climate programmes. Velocity (displacement) means and statistics will be available for
much of the world at the end of the deployment
period; results for the tropical Pacific (Davis,
1998b), southwestern Atlantic (Davis et al., 1996)
and Labrador Sea (Lavender et al., 2000a) are
already published, as described in the previous
subsection. Maps will likely be included in the
hydrographic atlases along with isopycnal property maps. These groups also construct dynamic
topography maps from the averaged float displacements, for better comparison and integration with
hydrographic data sets.
TOGA and WOCE, as well as many other funding agencies in many countries, have provided the
most comprehensive surface drifter coverage yet
available. These observations include water temperature as well as velocity, and many drifters also
measure meteorological parameters. Surface drifter
data and products are available online at this time
through the surface drifter data assembly centre.
Surface fluxes
Surface flux products, including winds and components of heat and water fluxes, are computed and
compiled by a number of different organizations,
described by Lindstrom and Legler, Chapter 3.5,
Bryden and Imawaki, Chapter 6.1, and Wijffels,
SECTION 7 INSIGHTS FOR THE FUTURE
534
three-fold: collection of XBT data; development of
the profiling float; and provision of the framework
for quality control and archiving of the datasets.
In these efforts, only the high-resolution XBT programme (closely spaced profiles along selected
seasonally repeated merchant ship transects) was
entirely a WOCE programme; all other XBT work
has been joint with other climate programmes, such
as Tropical Ocean Global Atmosphere (TOGA),
which recognize the importance of regular thermal
sampling in the upper ocean for climate studies.
Float work and especially technical development
was also supported by other programmes in addition to WOCE, although the primary impetus and
much of the funding came from WOCE.
The thermal data are used as inputs to developing coupled prediction models. The Global Temperature–Salinity Pilot Project (GTSPP), run by the
National Oceanographic Data Center (NODC) in
the US, is the central resource for this programme
at this time. After collection of XBT data at
NODC, data are quality-controlled by three data
assembly centres: the US’s Scripps Institution of
Oceanography (SIO) (Pacific Ocean), Australia’s
Commonwealth Scientific and Industrial Research
Organization (Indian Ocean), and the US’s NOAA
Atlantic Oceanographic and Meteorological Laboratory (Atlantic Ocean). Data are available online
from the NODC. Profiling float data, for which
collection began around 1995, are still in an experimental stage, particularly with regard to archiving;
at this time only the temperature profiles are sent
to NODC.
Climatologies, including monthly averages of
temperature, heat storage and mixed-layer depth
fields and anomalies, have been produced by the
Joint Environmental Data Analysis Center (JEDAC)
at SIO (White, 1995) and are easily accessible
online at SIO and through the World Meteorological Organisation/Intergovernmental Oceanographic Commission site at Lamont-Doherty Earth
Observatory. Analyses for the Indian Ocean are
available online from CSIRO in Australia. The
fields are used for basic research and comparison
with models (e.g. Auad et al., 1998).
Velocity data sets
Velocities are measured directly in three ways in
WOCE: current meters at fixed sites, Lagrangian
drifters and floats, and acoustic Doppler current
profiling. Current meter records, including means
and statistics, constitute a type of climatology,
albeit based only on the time period of each current meter record. Pre-WOCE (pre-1989) current
meter statistics were compiled by Dickson (1990),
with an update from the WOCE period compiled
by Dickson, Medler and Wooltorton; both are
available online through the WOCE Current
Meter Data Assembly Centre (CMDAC). The
CMDAC also maintains statistics for WOCE
current meters.
WOCE provided a major expansion of subsurface float coverage compared with the limited
deployments prior to WOCE and critical breakthroughs in float technology with the aim of
global coverage. Many of the subsurface floats at
mid-depth deployed in WOCE are still functioning
and data are still being recorded. The next few
years will see continuation and expansion of the
WOCE profiling float coverage (the Argo programme), largely for the temperature (and salinity)
profiling capabilities of the floats, as part of international climate programmes. Velocity (displacement) means and statistics will be available for
much of the world at the end of the deployment
period; results for the tropical Pacific (Davis,
1998b), southwestern Atlantic (Davis et al., 1996)
and Labrador Sea (Lavender et al., 2000a) are
already published, as described in the previous
subsection. Maps will likely be included in the
hydrographic atlases along with isopycnal property maps. These groups also construct dynamic
topography maps from the averaged float displacements, for better comparison and integration with
hydrographic data sets.
TOGA and WOCE, as well as many other funding agencies in many countries, have provided the
most comprehensive surface drifter coverage yet
available. These observations include water temperature as well as velocity, and many drifters also
measure meteorological parameters. Surface drifter
data and products are available online at this time
through the surface drifter data assembly centre.
Surface fluxes
Surface flux products, including winds and components of heat and water fluxes, are computed and
compiled by a number of different organizations,
described by Lindstrom and Legler, Chapter 3.5,
Bryden and Imawaki, Chapter 6.1, and Wijffels,
SECTION 7 INSIGHTS FOR THE FUTURE
534