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7
Biogeochemical Dynamics
in the Ocean
OVERVIEW
In its 1988 report, Toward an Understanding of Global Change: Initial
Priorities for U.S. Contributions to the IGBP, the Committee on Global Change
recommended a research initiative on oceanic biogeochemical cycles (NRC,
1988~. The objective of the effort was to develop the capability to predict
the effect of projected climatic change on the ocean's physical, chemical,
and biogeochemical processes, especially as they feed back to climate via
the release or absorption of radiatively important gases such as carbon diox-
ide and organic sulfur species. This chapter identifies the current efforts to
meet that challenge, both with existing programs and with recommendations
for new efforts.
Global change is not limited to the physical aspects of climate. It af-
fects, and is affected by, living processes. Today we know that the earth
works as a system, and that physical, chemical, biological, and geological
processes all interact to yield the constantly changing system of our envi-
ronment. We also know that the ocean plays a key role in these interactive
processes. For example, the importance of the ocean in the biogeochemical
This chapter was co-authored for the Committee on Global Change by D. James
Baker, Joint Oceanographic Institutions, Inc., Chair; P. Brewer, Woods Hole Oceanographic
Institution; H. Ducklow, University of Maryland; I. McCarthy, Harvard University;
M. Reeve, National Science Foundation; and B. Rothschild, University of Maryland,
with further comments by N. Andersen, National Science Foundation; K. Bryan,
Princeton University; A. Jochens, Texas A&M University; W. Nowlin, Texas A&M
University; J. O'Brien, Florida State University; J. Price, Woods Hole Oceanographic
Institution; and C. Wunsch, Massachusetts Institute of Technology.
200
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BIOGEO CHEMICAL DYNAMICS IN THE OCEAN
201
cycles of all of the elements essential to life on earth has been recognized
for a long time. But the mechanisms that cause these cycles and their
interaction with environmental change are not well understood. Moreover,
the nature and even the sign of the possible feedbacks between environmental
change and biogeochemical cycles driven by the activities of living organisms
are unknown.
An example that shows how biological processes in the ocean can affect
global change comes from the aerosols that are formed in the atmosphere
over the ocean from the oxidation products of dimethylsulfide, a gas emitted
by marine phytoplankton. Many of the physical properties of low-level
clouds are dependent on the properties and distribution of the aerosols upon
which the cloud droplets are formed. The aerosols affect the reflectivity,
lifetime, and precipitation properties of these clouds. Because climatic
factors may affect the activity of the marine phytoplankton, there is the
possibility of a climatic feedback loop through the formation of these aero-
sols. In order to understand this process, efforts must be made to incorpo-
rate microphysical and chemical influences on cloud processes in global
models. The relationships between phytoplankton activity, the emission of
dimethylsulfide to seawater and subsequently to the atmosphere, the oxida-
tion of dimethylsulfide to produce sulfate aerosols, and the relation of these
aerosols to cloud condensation nuclei and the albedo of the earth need to be
clarified, including the overall relationship to climatic changes (Charlson et
al., 1987~.
This is just one example of a specific linkage between oceanic chemistry,
biology, atmospheric chemistry, and climate that underscores why, if we are
to understand the cycles of the chemical elements, we must first understand
their uptake and reactions with the ocean and its ecosystems. Another
comes from the importance of the trace elements such as iron in determining
global rates of phytoplankton new production. Offshore Pacific water, for
example, appears to require supplemental iron from the atmosphere or con-
tinental margin to be optimally suited for plankton growth (Martin et al.,
1990~. Yet another example can be taken from the effect of ozone depletion
on antarctic organisms. The potential increased levels of ultraviolet radiation
could affect the phytoplankton that constitute the base of the food web in
aquatic ecosystems by reducing the amount of primary production and altering
community structure.
A principal practical concern is the role that the interactions of atmo-
spheric and oceanic physical and chemical dynamics have on the long-term
fluctuations of animal populations in the oceans, coastal seas, and estuaries.
Whole economies are dependent~on and sensitive to the interannual and
decadal regional fluctuations of harvestable biomass, such as those correlated
with E1 Nino. We need to develop an understanding of the complex interplay
of biological and physical forcing on life history stages of animal populations,
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RESEARCH STRATEGIES FOR THE USGCRP
which can produce very large swings in the harvest of major components of
the global ocean biomass from decade to decade.
This chapter focuses on five areas of biogeochemical dynamics in the
ocean: biogeochemical fluxes, with an emphasis on carbon; the ocean-
atmosphere interface; the oceanic ecosystem response to climatic change;
the underlying physical processes in the ocean and atmosphere; and processes
in the polar regions. The status of ongoing and proposed programs and
ways in which they can be enhanced are discussed. Studies of biogeochemical
processes in the coastal regions and air-sea fluxes, in particular, need fur-
ther work. The upper ocean also needs more study, both in the area of
physics and in biological processes.
Support for long-term monitoring in situ and by satellite-borne instru-
ments, with an emphasis on carbon dioxide, ocean color, circulation, and
winds, is strongly urged. It will also be important to provide support for the
near-term research satellite missions in the early 1990s and the Earth Observing
System (EOS) in the late 1990s to obtain the necessary data. The importance
of long-term monitoring for physical, biological, and chemical variables in
the ocean is underscored. The history of physical and biological events
such as E1 Gino needs to be extended as far back in history as possible,
using the proxy record as well as documentation, in order to define the
statistical variability of these events (see chapter 3~. Finally, the committee
urges the development of improved ties among programs.
STATUS OF EXISTING EFFORTS
Biogeochemical Fluxes
The need for understanding biogeochemical cycles in the ocean led to a
number of focused studies and advances in measurement capability in the
1970s and 1980s. The capability for global measurement of ocean color by
satellite-borne instn~ments and the subsequent inference of biological productivity
have provided new impetus to these studies. Also developed were in situ
techniques for direct measurement of the vertical transport of biogenic ma-
terial in the water column by sediment traps as well as high-precision methods
for the detection of trace species in very small amounts.
The understanding and new ideas from the various programs and the
capabilities provided by the new techniques led to the development of the
international Joint Global Ocean Flux Study (JGOFS) (SCOR, 1987~. The
U.S. program has its counterparts in several other nations, including the
U.K., France, Germany, and Japan. The goal of JGOFS is to determine and
understand on a global scale the processes controlling the time-varying
fluxes of carbon and associated biogenic elements in the ocean and to evaluate
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203
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RESEARCH STRATEGIES FOR THE USGCRP
becomes interdisciplinary. Such planning for studies of interdisciplinary
coastal processes is now a part of international planning with both the IGBP
and the Intergovernmental Oceanographic Commission (IOC). The IGBP is
now planning a Coastal Ocean Flux and Resource Study to help address
these issues.
It should also be noted that the Department of Energy is reshaping its
entire program dealing with coastal areas to specifically address interdisci-
plinary issues. A number of European efforts also address the coastal areas
and are complementary to JGOFS. In addition, NOAA has developed a
coastal program, and the EPA recently held a workshop on coastal ocean
physics and climate change, aimed at the issues involved in the assessment
of ecosystem response in the coastal ocean.
Ocean-Atmosphere Interface
Fluxes across the sea surface must also be studied. The atmosphere can
provide an important transfer path for natural and pollution-derived chemi-
cals entering the ocean. Some atmospherically derived species, especially
nutrients like iron, may have important impacts on productivity in some
areas of the ocean. The ocean is also an important source for several
chemicals in the atmosphere, including sulfur species, certain low molecular
hydrocarbons, and some halogenated species. It is important that the JGOFS
program work closely with atmospheric chemistry programs so that fluxes
from the atmosphere are measured and the mechanisms for transfer understood.
Mechanisms to encourage such close interaction between programs need to
be established. The physical fluxes of heat, water, and momentum are also
important; these are discussed in the section "Physical Processes?' (below).
During the late 1970s, there was a recognition by atmospheric chemists
that trace species in the atmosphere including methane, nitrous oxide, and
chlorofluorocarbons can have a cumulative effect on climate equal to that of
carbon dioxide. A Global Tropospheric Chemistry Program (GTCP) (NRC,
1984) and an International Global Atmospheric Chemistry (IGAC) program
(Galbally, 1989) have been proposed to study the sources, transport, reactions,
and removal of trace species in the global atmosphere.
The GTCP will measure and model concentrations and distributions of
gases and aerosols in He lower atmosphere, chemical reactions among atmospheric
constituents, sources and sinks of important trace gases and aerosols, and
exchange of gases and aerosols between the troposphere and the biosphere,
the earth's surface, including the ocean, and the stratosphere. Activities
include field, laboratory, and modeling studies designed to provide a better
understanding of the chemical reactions in the lower atmosphere (troposphere)
and to develop new instruments for measuring trace atmospheric constituents.
Much of the GTCP will take place in the context of the IGAC program.
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BIOGEOCHEMICAL DYNAMICS IN THE OCEAN
205
IGAC is an initiative of the Commission of Atmospheric Chemistry and
Global Pollution of the International Association of Meteorology and Atmospheric
Physics of ICSU. It should be noted that neither of these programs is aimed
at the carbon dioxide issues. The designation of IGAC as an IGBP core
project program follows a decision reached jointly by the Commission and
the Special Committee for the IGBP to expand the original scope of IGAC
to include a strong biological component dealing with sources and sinks of
. .
erogenic gases.
The exchange of trace species between the ocean and the atmosphere is
an important boundary process for the ocean. Thus the mechanisms for
interaction between these atmospheric chemistry programs and JGOFS and
related programs in the ocean must be enhanced. A close working relationship
is now developing between JGOFS and IGAC, and plans are being made for
a formal relationship between these two programs, which would be particularly
appropriate since they are both part of the IGBP.
Oceanic Ecosystem Response to Climatic Change
Global oceanic fluxes of carbon and other materials are mediated through
the complex interactions of the growth, reproduction, and mortality dynamics
of oceanic communities and their constituent populations. This happens
through the consumption of primary production, transfer up the food chain
to harvestable resources, recycling of primary nutrients to enable continued
primary production, processing of residual material, and its sinking and
sediment burial. Biological responses to changes in climate and the implications
for carbon flux are important topics that are receiving increased attention
today. The initial planning stages of a new program, the Global Ocean
Ecosystem Dynamics (GLOBEC) program, are now under way. GLOBEC
is aimed at understanding how a changing global environment will alter the
stability and productivity of marine ecosystems. Note that the variability in
primary production (a vital concern to the JGOFS program) cannot be understood
without taking into account the organisms that supply a significant compo-
nent of nitrogen to the phytoplankton and at the same time control, at
certain places and times, phytoplankton abundance, through grazing.
Equally important is the role of the secondary producers of the lower
levels of the food chain in the transfer of energy and carbon up the food
chain. This transfer has important implications for the animal populations,
e.g., fisheries, of vital concern to humans. The need for understanding the
physical and chemical oceanography of the upper ocean, where most of the
life occurs, is a fundamental aspect of understanding the biological systems.
Most marine species, including zooplankton, bottom-living animals, and
fish, base their strategy for long-term survival on the production of hundreds,
thousands, and even millions of offspring by every female adult. The implications
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RESEARCH STRATEGIES FOR THE USGCRP
of this almost universal strategy are obvious. First, survival of the indi-
vidual in the ocean is already very tenuous, and high rates of mortality are
virtually guaranteed. Second, changes of seemingly insignificant percentages
in survival (e.g., between 0.01 and 0.001 percent) produce enormous differences
in adult numbers and biomass, considering that, for example, fish can grow
through 6 orders of magnitude of biomass increase. The central question
therefore at the heart of the GLOBEC program is "what is the potential for
global-scale climatic change to disturb the already extreme variability in-
herent in natural ecosystems beyond the point of recovery?" For instance,
what will be the fate of coral reefs, estuaries, or major fish stocks?
The GLOBEC planning currently is examining the best ways to address
(1) the development of new ecological theory applicable to oceanic ecosystem
dynamics, (2) new modeling approaches that can lead to prediction of eco-
system changes, and (3) a new generation of in situ technology to measure
populations as they fluctuate in real time in response to the rapidly changing
physical environment (NRC, 1987~. As these new ideas and techniques are
developed, they will be incorporated into an ongoing program and will
provide insights into biogeochemical processes.
Physical Processes
The fundamental physical setting of the ocean and the interaction of the
ocean with the atmosphere are essential aspects of the chemical and biological
interactions. As a consequence, it is essential that such programs as the
Tropical Ocean-Global Atmosphere (TOGA) program, WOCE, and the Global
Energy and Water Cycle Experiment (GEWEX) be carried out by the World
Climate Research Program (WCRP) to provide the necessary description
and understanding of the physical processes in the ocean.
Tropical Ocean-Atmosphere Interactions
Considerable progress has been made in the past 2 or 3 years in actually
predicting change in the study of E1 Nino, the periodic anomalous warming
(and cooling) that occurs in the tropical Pacific Ocean accompanied by
global atmospheric changes. The economic impacts of associated excess
rainfall, flooding, and droughts have been estimated in the billions of dollars.
To study this phenomenon, the WCRP developed the TOGA program as its
first major project in 1985. TOGA has established a quasi-operational monitoring
network of drifting and moored buoys, sea level gauges, and upper-layer
and meteorological measurements from volunteer observing ships in the
tropical Pacific, Atlantic, and Indian oceans. By focusing on the tropical
system, we are beginning to learn how the climate system works (NRC,
1990~.
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BIOGEOCHEMICAL DYNAMICS IN THE OCEAN
207
Studies are now being carried out to determine the frequency and magni-
tude of E1 Nino events in the geologic past, using the sediment record. The
information from the sediments also gives a record of biological activity.
This statistical data could be useful in understanding the long-period fluc-
tuations and interactions of biology and physics in the E1 Nino.
Global Ocean Circulation
On longer time scales, from interannual to decadal, we need to understand
such questions as how much heat is transported by the ocean and how does
the ocean take up and redistribute carbon dioxide and other trace gases
important in the radiative balance. To address these issues, the second
major ocean project of the WCRP is the World Ocean Circulation Experiment
(WOCE). Its primary goal is to develop models useful for predicting cli-
matic change and to collect the data necessary to test them. Specific parts
of the program will include efforts to determine and to understand on a
global basis the large-scale fluxes of heat and fresh water, their divergences
over 5 years, and their annual and interannual variability. WOCE will also
try to identify those oceanographic parameters, indices, and fields that are
essential for continuing measurements in a climate observing system on
decadal time scales and to develop cost-effective techniques suitable for
deployment in an ongoing climate observing system (U.S. WOCE Office,
1989; WOCE, 1988).
WOCE has as central observational elements a global observing network
of precision satellite measurements of the surface winds and currents, direct
current measurements, and precise measurement of temperature, salinity,
and chemistry. WOCE will begin its field phase in 1990. The JGOFS
program will use WOCE logistics to carry out a global survey of carbon
dioxide in the sea. In early 1991 the in situ programs will be supported by
the launch of the ESA's ocean satellite ERS-1. ERS-1 will provide global
wind measurements by scatterometer and surface topography measurements
by altimeter for ocean circulation. In 1992 the joint U.S.-French precision
altimeter mission TOPEX/POSEIDON will begin to provide accurate mea-
surements of surface topography. In 1995 the Japanese Advanced Earth
Observing Satellite will provide a flight for the NASA scatterometer (NSCAT),
and, in the late 1990s, altimetry and scatterometry will be provided by EOS
on the polar platforms.
A scatterometer measures the strength and direction of the surface wind
on the ocean and thus is of interest for WOCE studies of air-sea fluxes of
momentum. The direct effect of the wind is to produce turbulent mixing in
the ocean, a physical process that directly affects biological processes. Upwelling
in the ocean is related directly to the wind at the surface. Thus flight of a
scatterometer will greatly help in the description and interpretation of biological
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RESEARCH STRATEGIES FOR THE USGCRP
processes. This point underscores the need for better understanding of the
upper ocean.
With the various global data sets, modelers are expected to be able for
the first time to realistically portray the oceanic circulation and its interac-
tion with the atmosphere on a global scale. This information can be used to
help to develop models that include biological and chemical processes.
WOCE will be augmented by the NOAA Atlantic Climate Change pro-
gram, which will study air-sea interaction in the North Atlantic Ocean. The
Atlantic Climate Change program will provide valuable information on the
environmental context for biological studies (NOAA, 1990~.
For both TOGA and WOCE the primary question from the biogeochemical
point of view is whether these programs will provide the physical understanding
of the ocean that is needed to meet the objectives of JGOFS and related
biogeochemical programs. Close interaction between the planning for these
programs and the needs of the biogeochemical studies needs to be main-
tained. For example, it is clear that better understanding of the upper ocean
is required, but it is not clear whether TOGA or WOCE will collect data on
the upper ocean that is sufficient to meet the needs of the biogeochemical
programs. It will be the responsibility of the scientists involved in programs
like JGOFS and GLOBEC to identify what additional physical studies need
to be done.
Precipitation over the Oceans
It has long been recognized that the difference between precipitation and
evaporation the flux of fresh water-is one of the factors that influence
oceanic circulation and the chemistry and biology of the ocean. Although
evaporation can be estimated with some difficulty from sea surface temperature
and surface wind (surface humidity is also required, but difficult to measure
at sea), precipitation cannot, except at islands and from ships at sea.
The Global Precipitation Climatology Project (GPCP) provides precipitation
data from operational satellites. Sponsored by the WCRP, the program
incorporates conventional rain gauge measurements for continental areas
and satellite images for estimating water content and precipitation. GPCP
began operations in 1987 and will provide global precipitation fields for the
period from 1986 to 1995 (WOCE, 1988~.
The new satellite microwave techniques, which work in the frequency
ranges that are sensitive to the presence of liquid water, are already providing
measurements of rainfall over both oceans and land. However, previous
microwave measurements have all been made from sun-synchronous polar
orbit. Because diurnal rainfall variations are known to be large, such data
may not yield representative daily rainfall averages. The first scheduled
application of the techniques on a global scale from a special tropical, non
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BIOGEOCHEMICAL DYNAMICS IN THE OCEAN
209
sun-synchronous orbit over the oceans will be the Tropical Rainfall Mea-
surement Mission (TRMM), a joint U.S.-Japanese mission planned for the
mid-199Os. These measurements will be of importance to understanding
biological processes. In the late 1990s, rainfall measurements will be carried
out from the EOS polar platforms (NASA, 1986~.
Polar Processes
The importance of high-latitude studies needs to be emphasized. The
Arctic System Science (ARCSS) program is aimed at understanding the
physical, chemical, and biological interactions that link the arctic environment
to global climate. If successful, ARCSS will provide improved information
and predictive modeling capabilities of physical and biological conditions
and changes in the planet's environmentally sensitive polar regions. Using
data from ice and sediment cores, ARCSS should help to expand the understanding
of arctic paleoenvironments. JGOFS is beginning to include high-latitude
process studies in their planning (SCOR, 1990~.
Southern polar regions are also important. In its 1989 report The Role of
Antarctica in Global Change: Scientific Priorities for the IGBP, the Scien-
tific Committee for Antarctic Research (SCAR) noted that the Southern
Ocean covers only 10 percent of the world ocean but plays a major role in
the global carbon flux. It has a significant influence on the interannual
variation of the world ocean's capacity to take up atmospheric carbon dioxide.
Much of the world's deep water is formed in the sea ice zone of the Southern
Ocean, and high wind stress, local microbial productivity, and sea ice cover
all vary to produce a range of potential incorporation of gases in surface
waters. The flux of biogenic materials in the Antarctic is linked to the
formation of, sinking, and northward movement of cold water as well as to
Be transport pattern of water masses. Changes in the fluxes are well documented
in the upper layers of ocean sediments. JGOFS is now addressing issues of
the biogeochemical fluxes in the Southern Ocean, as part of integrated and
essential parts of the IGBP in the Antarctic.
One particular emphasis for an antarctic IGBP investigation? noted by
the SCAR group, is to study the effects of ocean changes on the dimethylsulfide-
emitting phytoplankton, as noted earlier. Abundant unicellular algae in the
Southern Ocean are emitters of dimethylsulfide, which, in the atmosphere,
may change cloudiness patterns and either enhance or diminish the greenhouse
effect.
Another subject of concern is the effect of ozone depletion on antarctic
organisms. The subsequent increased levels of ultraviolet radiation could
affect the phytoplankton that constitute the base of the food web in aquatic
ecosystems. Studies have shown that increased levels of ultraviolet exposure
result in reduced primary production and an altered community structure.
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RESEARCH STRATEGIES FOR THE USGCRP
By weakening the base of the food web and altering trophodynamic rela-
tionships, ultraviolet-induced changes could affect the entire Southern Ocean
ecosystem.
In terms of measurements in the polar regions, satellite-borne instru-
ments are invaluable. Currently, measurements are taken from operational
satellites such as the Defense Meteorological Satellite Program (DMSP),
which makes microwave measurements of snow and ice. The European
ERS-1 and the Japanese ERS-1 satellites will provide polar snow and ice
measurements until EOS is in place in the late 1990s.
STATUS OF MODELING AND MONITORING EFFORTS
The Need for Modeling
As indicated above, there are several large research programs either in
progress or planned for the early 1990s to study the role of the ocean in
climatic change. Moreover, the technology necessary for improving the
speed of computers to handle global ocean prediction models is developing
rapidly. It appears that the next generation of supercomputers, relying on
high-speed parallel processors and other new developments, will provide
the necessary number-crunching needed to incorporate the oceans in long-
term studies of climate in a physically realistic way.
Two kinds of models are required: (1) those that simulate the existing
knowledge (diagnostic) and (2) those that try to develop a better understanding
of the world (predictive). Both kinds of modeling are carried out in these
programs. A prerequisite for an efficient monitoring scheme that covers the
broad spectrum of physical and biogeochemical processes is to have models
of the way these processes work. Models of the physical processes and of
primary production processes are being developed through TOGA, WOCE,
and JGOFS. Development of models of secondary production is a major
raison d'etre for GLOBEC.
The Need for Monitoring
A major piece of a global effort to understand the linked physical and
biogeochemical systems is still missing: it is a routine, global, operational
ocean-observing system that monitors physical, chemical, and biological
parameters. Such a system must be put into place if we are to describe,
understand, and ultimately predict global change. For understanding
biogeochemical fluxes, it is especially important to monitor the dissolved
gases such as carbon dioxide.
For the atmosphere, we have the World Weather Watch (WWW), which
consists of a combination of satellite and in situ measurements in the atmo
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BIOGEOCHEMICAL DYNAMICS IN THE OCEAN
211
sphere. Each participating nation has a national weather service that pro-
vides local data for transmission on the Global Telecommunications System
(GTS). The worldwide satellite network, consisting of five geostationary
satellites operated by the United States, ESA, Japan, and India, and polar-
orbiting satellites operated by the United States and the Soviet Union, also
provides its data through the GTS. This operational system is the basis for
the World Weather Watch. It is driven by the customer needs of weather
forecasting and civil aviation.
But there is no equivalent system for long-term systematic oceanic observa-
tions, primarily because the same level of customer interest has not existed.
Most countries do not have the ocean equivalent of a weather bureau, and
those that do, like the United States, do not provide the necessary funding
to make it viable. In the United States the National Ocean Service of
NOAA has the charge for long-term observations, but there has never been
a sufficient federal funding commitment to make it work. We do have a
pilot monitoring scheme for the tropical Pacific Ocean as part of the TOGA
program. The data from this system have been valuable in helping TOGA
scientists develop an operational ocean model for E1 Nino predictions.
The international framework is in place, through the International Global
Ocean Station System (IGOSS), jointly sponsored by the Intergovernmental
Oceanographic Commission and the World Meteorological Organization.
IGOSS supports a global system of expendable bathythermograph (XBT)
and related measurements in the upper ocean from volunteer observing ships;
the data are transmitted to data centers by the GTS. But in the main, the
funds for these XBTs come from research programs like TOGA and WOCE.
If we are to see a long-term operational system, then we must find a way to
provide such instruments on a regular basis outside research funding. And
we must extend the measurements to include new techniques such as acoustics
and a wider set of physical, chemical, and biological parameters.
A beginning has been made in the monitoring of dissolved carbon dioxide
on a global scale by JGOFS, and there has been monitoring of biological
processes in the sea. For example, the monitoring of fisheries stocks sponsored
by the International Council for the Exploration of the Sea (ICES) in the
North Atlantic since the turn of the century still continues. Regular monitoring
of biological parameters has been carried out by the CALCOFI program off
the coast of California. Stations like Station Papa in the northwest Pacific
Ocean have carried out biological monitoring. The U.K. continuous plank-
ton recorder has been operated in the waters around the U.K. and all across
the Atlantic Ocean. Ocean color was monitored for several years by the
now-inoperable Coastal Zone Color Scanner on the Nimbus-7 satellite, but
as noted above in the section on JGOFS, we are facing a long delay in
ocean color monitoring now.
In the Antarctic, the SCAR group gave emphasis to monitoring changes
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RESEARCH STRATEGIES FOR THE USGCRP
in organisms and biological processes that are directly linked to environ-
mental changes. Phytoplankton, at the base of the marine food web, may be
more useful to monitor than the top marine predators, which can be affected
by a greater complexity of events. However, the uppermost predators, such
as seals, integrate changes over several seasons and may be better indicators
of long-term trends. Historical and cohort strength fluctuations in several
species of antarctic seals may be related to fluctuations in environmental
parameters such as pack-ice extent, krill, and even E1 Niho events. Corals
and molluscs show annual growth increments, and demographic analysis of
populations may show the integrated effects of past changes.
But this is only a start compared to the network of measurements that is
required. Understanding global change requires global measurements in
both the atmosphere and the ocean; for the long term, we will require operational
measurements. This transition from research to operations must be a focus
for the 1990s and into the twenty-first century.
Satellite measurements are essential to monitoring: for the first part of
the 1990s the various research missions that have been described above will
provide the necessary information. But for the late 1990s and beyond, for
true monitoring of global change, instruments of EOS need to be in place to
monitor ocean color, wind stress, and ocean currents, as well as ocean
temperature and rainfall. EOS is now scheduled to be launched in 1998. It
is important that the various research missions and systems proposed be
able to provide measurements until the EOS is in place, so that continuity of
data is provided. If there are delays in EOS, then ways to extend the
research missions should be considered.
RECOMMENDATIONS FOR ENHANCED SUPPORT,
NEW INITIATIVES, AND RESEARCH PROGRAMS
Based on the discussion above, the committee recommends the follow
ing:
Support for JGOFS as a core program of the IGBP. The JGOFS
carbon dioxide survey, modeling, and process study components should be
supported at the required levels. Ocean color by satellite is of particular
importance.
· Biogeochemical studies in the coastal regions. JGOFS, primarily aimed
at the open ocean, will not address all of the issues related to biogeo-
chemical dynamics in the ocean. Of special interest are the coastal regions.
It is in these regions that much of the biological productivity takes place,
and yet it has been difficult to define a program because of the complexity
of processes there. The committee believes that this should be a focus for
the next phase of planning. Nationally, such planning should be part of new
coastal oceanography programs. Internationally, such planning for studies
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BIOGEOCHEMICAL DYNAMICS IN THE OCEAN
213
of interdisciplinary coastal processes is now a part of IOC and IGBP plan-
ning.
· Chemical fluxes across the sea surface. It is important that the JGOFS
program continue to work closely with the relevant atmospheric chemistry
programs, in particular IGAC, so that fluxes between the atmosphere and
the ocean are understood and the boundary conditions are established. In-
creased cooperation and coordination between JGOFS and IGAC are en-
couraged and should be strengthened.
Ecosystems dynamics. It is important to recognize explicitly that the
role of the biota in global change in the ocean is not limited to its mediation
of biogeochemical cycles. Research must be conducted on the role of global
climatic change on the production, ecosystem structure, and fate of popula-
tions vital to the health and continued existence of humankind.
Physical studies of the ocean. The fundamental physical setting of the
ocean and its interaction with the atmosphere are essential aspects of the
chemical and biological interactions. As a consequence, it is essential that
programs such as TOGA and WOCE be fully funded so they can be carried
out successfully. Enhanced interactions and project planning between bio-
geochemical and physical programs are needed to ensure that the physical
understanding of the ocean that is needed to meet the objectives of JGOFS
and related biogeochemical programs is provided.
· Upper ocean physics and chemistry. Neither TOGA nor WOCE is
designed to provide the detailed physical knowledge of the upper ocean
needed for full understanding of biological processes and their changes. The
JGOFS and GLOBEC programs will need to identify clearly what is re-
quired to address these issues.
· New measurement techniques. Ocean color measurements in the near
and far term are essential. The SEAWIFS program needs to be supported,
as does the TOPEX/POSEIDON altimeter, the NASA scatterometer, and the
TRMM mission. Data from the European ERS-1 satellite should be fully
exploited. Finally, full support is needed for the flight of the ocean-related
instruments on EOS, now scheduled for 1998 and beyond. If there are
delays in the implementation of EOS, then ways to extend the proposed
research missions must be found in order to provide continuity of data. All
of these instruments are of crucial importance in describing and understand-
ing biological processes in the ocean.
· Modeling. With the various global data sets from the scientific programs
and from operational monitoring, modelers are expected to be able for the
first time to realistically portray the ocean circulation and its interaction
with the atmosphere on a global scale. This information can be used to help
to develop models that include biological and chemical processes.
· Monitoring. A major piece of a global effort to understand the linked
physical and biogeochemical systems is still missing: it is a routine, global,
operational ocean-observing system that monitors physical, chemical, and
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biological parameters. If a long-term operational system is to be in place,
ways must be found to provide such instruments on a regular basis outside
research funding. The international coordination mechanisms, such as the
IOC, could play a strong role. This transition from research to operations
must be a focus for the 1990s and into the twenty-first century.
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Representative terms from entire chapter:
upper ocean
