1.1.1 WOCE and The World Climate
Research Programme
The earth is mainly an ocean planet with 71% of
the surface covered by water, including up to 6%
coverage by sea ice. In total, perhaps as much as
85% of the earth’s surface is covered by either liquid
water (oceans, lakes, rivers, wet vegetation) or solid
water (snow, land-ice, sea-ice). Therefore, absorption of solar energy, which drives the earth’s climate
system, and evapotranspiration of water at the surface, are dominated by the oceans. In addition, the
global mean values of other energy fluxes, such as
sensible and latent heat flux and net long-wave radiation flux, at the surface are predominantly a result
of ocean–atmosphere interaction. The heat capacity
of only three metres of the ocean corresponds to the
heat capacity of the entire atmospheric column
above. Thus, even if the horizontal ocean currents
were much smaller, climate variability would still be
to a large extent an ocean-related phenomenon.
Both the atmosphere and the oceans exhibit a
complicated circulation pattern and their interaction determines much of the climate variability on
time scales from several hours (e.g. sea breezes) to
seasons, years, decades, centuries and millennia.
Understanding this variability is the essence of the
World Climate Research Programme (WCRP),
whose single and demanding goal has been formulated as follows:
To understand and predict, to the extent possible, climate variability and climate change,
including human influence on climate.
Only if climate variability is at least partially
understood will it be possible to detect and predict
climate change arising from external forcing, be it
by earth orbital parameter changes, solar irradiance variations, volcanic eruptions (the latter
counted as external forcing despite belonging to
the earth system) and/or human activities.
Given the importance of the oceans to climate,
it is not surprising to find the first two projects of
WCRP, the World Ocean Circulation Experiment
(WOCE) and the Tropical Ocean-Global Atmosphere (TOGA) study, were ocean related. Early
discussions and the formulation of science plans
for WOCE and TOGA were initiated by the
Committee on Climate Changes and the Oceans
(CCCO; Thompson et al., Chapter 1.3), jointly
sponsored by the Scientific Committee for Oceanic
Research (SCOR) of the International Council for
Scientific Unions (ICSU), and by the Intergovernmental Oceanographic Commission (IOC) of
UNESCO. The first decision on WOCE was made
in 1978, before WCRP was initiated by WMO and
ICSU in 1980. TOGA, which had been stimulated
by the 1982–83 El Niño event, the most intense of
the twentieth century until that date, was the first
formally implemented WCRP project lasting from
1985 to 1994. In 1982, WOCE, focused on building models necessary for predicting climate change,
became a central element of WCRP and effectively
complemented the atmospheric projects within the
broader scope of WCRP. Implementation of the
field programme of WOCE commenced formally
in 1990, at about the same time IOC became a
sponsor of WCRP.
Now, in 2001, we can look back to two very
successful projects of WCRP. First, TOGA has
made possible physically based predictions of
1.1
Climate and Oceans
Hartmut Grassl
3
OCEAN CIRCULATION AND CLIMATE
Copyright © 2001 Academic Press
ISBN 0-12-641351-7
All rights of reproduction in any form reserved
CHAPTER
Research Programme
The earth is mainly an ocean planet with 71% of
the surface covered by water, including up to 6%
coverage by sea ice. In total, perhaps as much as
85% of the earth’s surface is covered by either liquid
water (oceans, lakes, rivers, wet vegetation) or solid
water (snow, land-ice, sea-ice). Therefore, absorption of solar energy, which drives the earth’s climate
system, and evapotranspiration of water at the surface, are dominated by the oceans. In addition, the
global mean values of other energy fluxes, such as
sensible and latent heat flux and net long-wave radiation flux, at the surface are predominantly a result
of ocean–atmosphere interaction. The heat capacity
of only three metres of the ocean corresponds to the
heat capacity of the entire atmospheric column
above. Thus, even if the horizontal ocean currents
were much smaller, climate variability would still be
to a large extent an ocean-related phenomenon.
Both the atmosphere and the oceans exhibit a
complicated circulation pattern and their interaction determines much of the climate variability on
time scales from several hours (e.g. sea breezes) to
seasons, years, decades, centuries and millennia.
Understanding this variability is the essence of the
World Climate Research Programme (WCRP),
whose single and demanding goal has been formulated as follows:
To understand and predict, to the extent possible, climate variability and climate change,
including human influence on climate.
Only if climate variability is at least partially
understood will it be possible to detect and predict
climate change arising from external forcing, be it
by earth orbital parameter changes, solar irradiance variations, volcanic eruptions (the latter
counted as external forcing despite belonging to
the earth system) and/or human activities.
Given the importance of the oceans to climate,
it is not surprising to find the first two projects of
WCRP, the World Ocean Circulation Experiment
(WOCE) and the Tropical Ocean-Global Atmosphere (TOGA) study, were ocean related. Early
discussions and the formulation of science plans
for WOCE and TOGA were initiated by the
Committee on Climate Changes and the Oceans
(CCCO; Thompson et al., Chapter 1.3), jointly
sponsored by the Scientific Committee for Oceanic
Research (SCOR) of the International Council for
Scientific Unions (ICSU), and by the Intergovernmental Oceanographic Commission (IOC) of
UNESCO. The first decision on WOCE was made
in 1978, before WCRP was initiated by WMO and
ICSU in 1980. TOGA, which had been stimulated
by the 1982–83 El Niño event, the most intense of
the twentieth century until that date, was the first
formally implemented WCRP project lasting from
1985 to 1994. In 1982, WOCE, focused on building models necessary for predicting climate change,
became a central element of WCRP and effectively
complemented the atmospheric projects within the
broader scope of WCRP. Implementation of the
field programme of WOCE commenced formally
in 1990, at about the same time IOC became a
sponsor of WCRP.
Now, in 2001, we can look back to two very
successful projects of WCRP. First, TOGA has
made possible physically based predictions of
1.1
Climate and Oceans
Hartmut Grassl
3
OCEAN CIRCULATION AND CLIMATE
Copyright © 2001 Academic Press
ISBN 0-12-641351-7
All rights of reproduction in any form reserved
CHAPTER