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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
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,
202 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
BIOGEOCHEMICAL DYNAMICS IN THE OCEAN 203
204 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.
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
206 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~.
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
208 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
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.
210 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
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
212 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
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
214 RESEARCH STRATEGIES FOR THE USGCRP 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. REFERENCES Charlson, R.J., J.E. Lovelock, M.O. Andreae, and S.E. Warren. 1987. Oceanic phytoplanlcton, atmospheric sulphur, cloud albedo, and climate. Nature 326:6555- 6661. Galbally, I. (edgy. 1989. International Global Atmospheric Chemistry (IGAC) Pro- gram: A Core Project of the International Geosphere-Biosphere Program. IAMAP Commission on Atmospheric Chemistry and Global Pollution. Renwick Pride Pty Ltd., Albury, Australia. 55 pp. Martin, J.H., R.M. Gordon, and S.E. Fitzwater. 1990. Iron in Antarctic waters. Nature 345:156-158. National Aeronautics and Space Administration (NASA). 1986. From Pattern to Process: The Strategy of the Earth Observing System. EOS Science Steering Committee Report. Vol. II. NASA, Washington, D.C. National Oceanic and Atmospheric Administration (NOAA). 1990. Atlantic Cli- mate Change Program: Science Plan. Draft report. NOAA, Rockville, Md. 29 pp. National Research Council (NRC). 1984. Global Tropospheric Chemistry: A Plan for Action. National Academy Press, Washington, D.C. National Research Council (NRC). 1987. Recruitment Processes and Ecosystem Structure of the Sea: A Report of a Workshop. National Academy Press, Washington, D.C. 44 pp. National Research Council (NRC). 1988. Toward an Understanding of Global Change: Initial Priorities for U.S. Contributions to the International Geosphere- Biosphere Program. National Academy Press, Washington, D.C. National Research Council (NRC). 1990. TOGA: A Review of Progress and Future Opportunities. National Academy Press, Washington, D.C. Scientific Committee on Antarctic Research (SCAR). 1989. The Role of Antarctica in Global Change: Scientific Priorities for the IGBP. Prepared by the SCAR Steering Committee for the IGBP. ICSU Press, Cambridge, U.K. 28 pp. Scientific Committee on Oceanic Research (SCOR). 1987. The Joint Global Ocean Flux Study: Background, Goals, Organization, and Next Steps. International Council of Scientific Unions, Paris. 42 pp. Scientific Committee on Oceanic Research (SCOR). 1990. The JGOFS Science Plan. JGOFS/SCOR, Halifax, Canada, in press. U.S. World Ocean Circulation Experiment (WOCE) Office. 1989. U.S. WOCE Implementation Plan. U.S. WOCE Implementation Report No. 1. U.S. WOCE Office, College Station, Tex. 176 pp. World Ocean Circulation Experiment (WOCE). 1988. WOCE Implementation Plan. WCRP Series Vol. I and II, WCRP-11 and WCRP-12. WMO/TD No. 242 and 243. Geneva.
