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2 Future Science Needs How technological advances such as autonomous underwater vehicles and ocean observing systems will affect the role and characteristics of the future UNOL fleet with regard to accomplishing national oceanographic data col- lection objectives. How evolving modeling and remote sensing technologies will impact the balance between various research operations such as ground-truthing, hypothesis testing, exploration, and observation. The future ocean research agenda will address major societally rel- evant issues, including the oceanâs role in climate change, ecosystem health and sustainability, marine impacts on human health, management and exploitation of natural resources, and improving the predictability of natural hazards and maritime safety. These are inherently multidis- ciplinary challenges, involving the physical, chemical, biological, and geological sciences and allied fields such as air-sea interaction and atmo- spheric science. As an example, understanding the role of the oceans in the Earthâs climate system involves assessing the influence of topography on ocean circulation, storage and redistribution of heat, salt and car- bon dioxide (CO2) in the ocean, exchange of energy between the ocean and atmosphere, biogeochemical changes influencing ocean uptake and release of greenhouse gases, and the impacts of climate change on marine ecosystems. In addition, basic and exploratory oceanographic research will continue to be needed. 17
18 SCIENCE AT SEA New technologies (e.g., autonomous mobile systems, fixed seafloor observatories, and remote sensing and modeling) have revolutionized tra- ditional observation-limited oceanographic research, drastically increas- ing both the amount of data collected and the sophistication of analysis and assimilation. This does not lessen the continuing need for a versatile, technologically capable fleet of research vessels to support oceanographic research. Complex chemical and biological measurements will continue to require shipboard laboratories, and advanced technologies still require ships as platforms and tenders. Technological advances are discussed in detail in Chapter 3 but are introduced here in the context of major science research drivers. This chapter provides a brief survey of major research trends and needs that will influence the use and design of the future academic fleet. It is not intended as a comprehensive inventory of future oceanographic directions, which can be found in recent community planning documents and agency strategic plans (i.e., Baker and McNutt, 1996; Young et al., 1997; Trenberth and Clarke, 1998; Jumars and Hay, 1999; National Sci- ence Foundation, 2001; Ridge 2000 Program, 2001; Liss et al., 2004; MAR- GINS Office, 2004; MESH Workshop Steering Committee, 2005; National Oceanic and Atmospheric Administration, 2005; Daly et al., 2006; Joint Subcommittee on Ocean Science and Technology, 2007; National Oce- anic and Atmospheric Administration, 2008). For organizational ease, this chapter is broken down by disciplinary needs, with the recognition that there is considerable overlap due to the multidisciplinary nature of major scientific questions driving oceanographic research. Several case studies are shown in boxes to help to illustrate multidisciplinary oceanographic research programs that will incorporate new technology and drive the need for adaptable, capable research vessels. Box 2-1 is an example of a current research problem; Boxes 2-2 through 2-5 are hypothetical, near- future scenarios. Physical Oceanography Physical oceanography research focuses on the physical properties and dynamics of ocean processes. Future research needs are directed toward the role of ocean circulation and properties in climate change and the global carbon cycle. Global arrays of autonomous platforms and sensors and ship-based hydrography and process studies are essential ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ to progress in these research needs.ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ Ocean circulation changes in the full water column have been linked to a wide range of climatic variations that are of clear and critical interest to society. ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ Ship-based measurements are needed (Hood et al., 2009) to
FUTURE SCIENCE NEEDS 19 â¢ Reduce uncertainties in global freshwater, heat, and sea level budgets; â¢ Determine ocean ventilation and circulation pathways and rates using chemical tracers; and â¢ Determine the variability in and controls of water mass formation and properties. Physical oceanography has been transformed by the numerous auton- omous sampling devices currently available (e.g., moorings, drifters, floats, autonomous underwater vehicles [AUVs], gliders), which increased sampling in the upper ocean to a rate and density unparalleled by ships. Research vessels are still needed to measure large-scale changes in ocean heat and freshwater fluxes, deep ocean variability below 2000 meters, and the anthropogenic inventory of CO2 (Garzoli et al., 2009). Many cli- matically important carbon and related transient tracer parameters cannot be measured from autonomous devices with present-day technology, and few floats, gliders, and AUVs are able to operate to the full depth of the water column. While some of these instruments will operate to greater ocean depths in the future, there will continue to be parts of the deep ocean that cannot be reached without ship-based equipment. High-qual- ity, ship-based observations will also continue to be essential for calibra- tion of water column measurements made from autonomous devices. The deep ocean accounts for more than half of the total natural oce- anic carbon inventory. As anthropogenic carbon begins to invade the deep oceans in nonhomogeneous ways, it will continue to be critical to monitor changes in deep ocean carbon content. For example, observations of transient tracers (Willey et al., 2004), particularly in the high latitudes, strongly suggest that ventilation by atmospheric gases is more rapid than previously estimated. In addition, observations of biogeochemical param- eters show greater-than-expected variations at depth, which suggest that natural and/or climate-induced change is having a greater effect on deep waters than was previously assumed. Ship-based information and global sensor arrays will be critical to evaluate ocean general circulation models and provide data constraints for inverse models. Process studies, such as deliberate tracer and mixing experiments (see Box 2-1), will continue to require research vessels as plat- forms for science, as will the continuation of established time series (Ber- muda Atlantic Time Series, Hawaii Ocean Time Series, Atlantic Meridio- nal Overturning Circulation at 26.5Â°N, Line W mooring and hydrographic time series in the North Atlantic). ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ Global surveys are the most effective âThis lower volume between the seabed and 2000 meters depth, taken over its total global area, constitutes more than 50 percent of total oceanic volume.
20 SCIENCE AT SEA Box 2-1 Salt Fingers Show Vigorous Ocean Mixing Incomplete understanding of ocean mixing has been a limitation in predicting Earthâs future climate, specifically for modeling the oceansâ absorption and stor- age of climatically important properties, including heat and carbon dioxide. For decades, scientists have known that in certain parts of the ocean, layers of warm salty water of subtropical origin overlay cooler and fresher water of Antarctic ori- gin. The interaction of these layers creates âsalt fingers,â salty staircases driven by small-scale convection. Using data from a ship-based process study in the North Atlantic, it was discovered that salt fingers transform the temperature and salinity structure of water entering the Caribbean Sea. The resultant increase in salinity and density preconditions the Antarctic water at intermediate depths for sinking at high latitudes of the North Atlantic. Sampling from a ship allowed direct measurement of the vertical spreading rate of a passive tracer injected in the middle of a staircase. This allowed quantification of the effect of the salt fingering on enhanced mixing within the thermocline. The resultant mixing is an order-of-magnitude greater than the background mixing due to the breaking of internal waves (Schmitt et al., 2005). These results highlight the need to include mixing due to salt fingering in climate models. means for quantifying the variability of a large suite of physical and biogeochemical parameters, and global full-depth reassessments of the temperature, salinity, carbon, and related tracer distributions are a critical component of a global ocean and climate observing system (Hood et al., 2009). These surveys will continue to require Global class vessels, which are the only U.S. ships with sufficient endurance and range. Large-scale observing networks such as the Argo array, composed of 3000 profil- ing floats equipped with conductivity-temperature-depth (CTD) sensors, revolutionized scientistsâ view of the ocean by providing extraordinary temporal and spatial coverage in the upper 2000 meters of the water col- umn. However, these arrays can increase pressure for research vessels for deployment and calibration via ship-based datasets. Ocean acoustics, the branch of physical oceanography that studies the physics of sound in the ocean, will also continue to require ship-based experimentation and advances in acoustically quiet technologies. Shal- low-water, high-frequency, and long-range acoustics, as well as acoustic monitoring of sediment transport, will continue to utilize a variety of oceanographic instrumentation. Large research vessels will be needed to deploy and recover moorings and fleets of gliders. For these types of studies, future research vessels should be as acoustically quiet as possible (discussed in Chapter 4).
FUTURE SCIENCE NEEDS 21 Research needs for physical oceanography in coastal environments are similar to those in the deep ocean, but are complicated by factors such as proximity to large river plumes, physiography of the continental shelf, ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ and human activities that modify material fluxes from land and atmos- pheric deposition across broad shelf areas (Figure 2-1). The continental ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ margin is more sensitive than the deep ocean to tidal and wind-driven circulation patterns, varying penetration of sunlight, and the interaction between river, estuary, and coastal zone runoff and upwelling events and eddy exchanges. Sample collection in coastal regions often occurs on smaller spatial and temporal scales than for deep ocean physical ocean- ography and is especially likely to require vessels with shallow drafts and excellent maneuverability and station keeping. Research needs for coastal currents and physical dynamics will be driven by advances in coastal ocean observing systems and associated sensors, and will be best met by more capable Regional/Coastal and Regional class vessels. Figure 2-1 color.eps Figure 2-1â Important physical processes in continental margins (reprinted from Liu et al., 2009; with kind permission of Springer Science & Business Media). bitmap
22 SCIENCE AT SEA Chemical Oceanography The field of chemical oceanography is directed toward understanding the distribution, transformations, and rates of cycling of the major and minor elements in the oceans. Major research issues driving current and future research include â¢ The oceanâs role in the global carbon cycle, including oxygen and nutrient budgets that control biological productivity; â¢ Ocean cycling of climate-active gases (greenhouse gases, aerosol precursors, and stratospheric ozone-depleting substances); â¢ Ocean acidification resulting from ocean uptake of CO2 and other anthropogenic emissions; and â¢ Quantifying fluxes of trace elements and isotopes into the ocean and developing an accurate understanding of the processes con- trolling their distributions. Research needs include determining the regional and seasonal dis- tributions of macro- and micronutrients that regulate primary productiv- ity and influence ecosystem structure in the oceans, and characterizing the reservoir of dissolved and particulate organic carbon to understand its origin, cycling, and fate. Future research will encompass large-scale global ocean surveys (e.g., GEOTRACES; GEOTRACES Planning Group, 2006) and multidisciplinary regional process studies that interpret and constrain understanding of the paleoceanographic record through iden- tification and quantification of chemical fluxes into the oceans and by developing greater understanding of the tracer potential of materials such as trace elements and isotopes. These types of research will require Global class ships that are capable of globally ranging, multi-investigator cruises with facilities that include adequate clean laboratory space and berthing accommodations for a large science party. With the exception of salinity measurements, temporal and spatial chemical variability in the oceans is poorly documented, even for mac- ronutrients such as nitrate and silicate. Almost all chemical and isotopic analyses cannot be done remotely and require ship-based hydrographic water sampling and shipboard or post-cruise laboratory work. Therefore, a primary driver for chemical oceanography cruises is clean laboratory space and an underway scientific seawater supply. A variety of new analytical approaches have greatly improved the capability to provide molecular analyses of carbonaceous material in the oceans (i.e., liquid chromatography-mass spectrometry, Fourier transform ion cyclotron resonance mass spectrometry). Exploitation of these and other advanced analytical techniques will spur the demand for ship-based water sampling for the foreseeable future.
FUTURE SCIENCE NEEDS 23 Box 2-2 Open Ocean Blooms in the North Pacific Satellite ocean color observations have revealed large ephemeral open ocean plankton blooms (Wilson, 2003), but their origin, dominant species, and impact on biogeochemical cycles remain unresolved. In the following hypothetical future scenario, scientists investigate whether these blooms are intense sites of carbon export and how they affect food web dynamics. Although these blooms have been observed regularly in the North Pacific during the same season, scientists have not yet determined if they export particulate organic carbon (POC) to the deep sea or if it is instead remineralized near the sea surface. Routine glider patrols and Argo float data could indicate increased eddy activity, one characteristic of a potential incipient plankton bloom. After analyzing these data, scientists could schedule a cruise onboard an Ocean class vessel with a fleet of autonomous platforms, utilizing broadband communications to receive regular updates of satellite and modeling data regarding bloom development. Upon arrival at the site, a fleet of smart platforms would be deployed to track bloom expansion and movement. A ship-based, semi-automated command system will integrate in situ, remote sens- ing, and model information to intelligently navigate the AUVs. Scientists could then use detailed information from the AUVs to carefully target water sample col- lection, deploy drifting sediment traps, and launch net hauls to characterize the plankton bloomâs impact on the food web and on element biogeochemical cycling. Researchers could use the information collected during the event to inform and refine global models. The development of in situ chemical sensors for oceanography is an active area of research (Buffle and Horvai, 2000; Varney, 2000). Devices include electrochemical and colorimetric sensors capable of detecting various gases (oxygen [O2], nitrogen [N2], CO2) and nutrients (nitrate, silicate), and mass spectrometers for trace gases (methane [CH4]). These types of sensors are increasingly utilized on limited-duration drifters and buoys, and it is expected that in the future these sensors will be incorpo- rated into large-scale observational systems such as the Argo float array. Such sensor networks are needed to detect changes in ocean chemistry associated with climate change. Before sensors can be used in this man- ner, stringent requirements for calibration and stability and long duration deployment will have to be addressed. These sensors will, however, pro- vide only a small subset of the chemical, isotopic, and kinetic parameters that need to be measured to achieve a process-level understanding of the factors controlling seawater chemistry. Although new sensors are cur- rently under development for the detection of a full range of chemical tracers, a majority of geochemical work in the foreseeable future is likely to be limited to shipboard sampling and analysis.
24 SCIENCE AT SEA Satellite-based measurements of ocean color, sea surface temperature, and sea surface height have proven increasingly important to chemical, biological, and physical oceanography as a guide for process-oriented field studies (see Box 2-2) and as a basis for extrapolating in situ chemical measurements (McGillicuddy, 2009). A new space-borne ocean salinity sensor is scheduled for launch in late 2009 (European Space Agency, 2009). Satellite detection of specific chemicals (such as nutrients) in the oceans is not currently achievable and is unlikely to play a significant role in the near future. Global carbon cycle research will also need to focus on continental margins. Future research will focus on biogeochemical processes along coastal margins, offshore particulate fluxes, sediment dynamics, and interactions between benthic and pelagic processes. While data collected from coastal observing systems will help to quantify carbon sources and sinks in this region, Regional/Coastal and Regional class vessels capable of working in the nearshore can collect a greater variety and volume of sediment, biological, and water samples in areas that are difficult to access using stationary or autonomous instruments, especially in response to unpredictable events. Atmospheric Chemistry and Air-Sea Exchange The exchange of trace gases and aerosols between the ocean and the atmosphere exerts a major influence on the composition, reactivity, and radiative properties of the atmosphere. Major research themes in atmo- spheric chemistry involving the oceans include the following: â¢ Tropospheric and stratospheric photochemistry â¢ Direct and indirect aerosol radiative forcing â¢ Atmospheric deposition of aerosol-borne nutrients derived from desert dust or anthropogenic pollutants. These issues represent significant uncertainties in climate forcing and feedback and are poorly parameterized in the current generation of cli- mate models. Research needs include determining the saturation state of many trace gases in the surface ocean, assessing the reaction and path- ways of climate-active gases, and characterizing the composition, physical properties, and depositional patterns of aerosols (Lambin et al., 1999; Liss et al., 2004). Atmospheric chemistry has some unique observational challenges because of the sensitivity of the atmosphere to a wide range of trace- level chemicals and because atmospheric transport and mixing are so rapid. Progress in marine atmospheric chemistry is observationally lim-
FUTURE SCIENCE NEEDS 25 ited, with the need for broad spatial and temporal coverage as well as detailed in situ process studies. Future research will involve a combina- tion of airborne and ocean-borne research platforms, with increasing use of unmanned aircraft and drones in conjunction with research vessels and buoys. The academic fleet will continue to play a unique and essential role in atmospheric chemistry research programs because it provides access to the marine atmosphere with a duration and payload unmatched by other platforms. Research vessels will also continue to play an important role as a test bed for new analytical instruments and as a platform for calibra- tion and validation of the next generation of satellite-based atmospheric chemistry instruments. The air-sea interface is a complex region that controls the transfer of heat, momentum, gases, and aerosols between the ocean and the atmo- sphere. Processes controlling air-sea exchange span a wide range of scales from the sub-millimeter thickness of the sea surface microlayer to the basin-wide scale of major ocean currents and atmospheric circulation sys- tems. The interface is physically, biologically, and chemically complex. No adequate theoretical framework exists to describe transport across the air- sea interface, and the conditions occurring in nature cannot be replicated easily in the laboratory. Future research will focus on the development of physically based parameterizations of air-sea fluxes for use in regional and global climate models. This will require in situ observational process studies, involving general purpose and specialized research vessels as well as air-sea interaction buoys and aircraft. In situ process studies of air-sea gas and aerosol transfer have increased in both size and complex- ity, involving a variety of techniques including deliberate inert gas tracers, eddy covariance flux measurements, and passive and active sensing of the sea surface. Upscaling of fluxes from local to regional and global scales will involve buoys, satellite measurements, and modeling. The need for ship support of air-sea interaction studies is likely to increase in the future to carry out process studies, to support regional air-sea buoy networks, and to validate satellite-based measurements. Biological Oceanography Biological oceanography focuses on marine organisms and their rela- tionship to ocean circulation, nutrients, and the biogeochemical cycling of elements. Emerging research issues in this field include â¢ Global biogeochemical cycles, â¢ Organismsâ role in and response to climate change, â¢ Linkages between marine ecosystems and human health, and â¢ The dynamics and basin-wide connectivity of marine populations.
26 SCIENCE AT SEA The biological pump plays an important role in the concentration of atmospheric CO2. Current approaches to studies of the biological pump marry ship-based observations with autonomous systems, fixed obser- vatories, and remote sensing and modeling. Newly developed genetic tools are presently used to examine the composition and function of marine microbes at the base of the food web, and they are being used to identify species of zooplankton and fish and their population structure (Bucklin, 2000; Scholin et al., 2009). In the future, these genetic tools (and others, including new biogeochemical sensors) will be adapted for use on autonomous platforms, ocean observatories, and systems such as Argo, and will lead to worldwide, data-rich measurements of the organisms that drive biogeochemical cycles. However, in the near future, research vessels will still be required to collect water and organisms for biologi- cal oceanographic studies. There will be a continued need for sustained, established time series. Coastal ecosystems and human health are inextricably linked, yet these ecosystems are increasingly threatened by nutrient pollution, toxic bacteria and algae, and resource exploitation (e.g., Bank et al., 2007; Chen et al., 2008). Marine issues that directly impact human health and econom- ics, such as harmful algal blooms (HABs), will require multidisciplinary, focused process experiments to better understand how these events occur (see Box 2-3). Since these issues tend to be near coastal margins, Regional Box 2-3 Nearshore Harmful Algal Blooms In the near future, environmental observations from coastal moorings, regular glider patrols, Argo floats, and satellite data from the ocean surface will be fed into physical-biological models to monitor possible harmful algal bloom develop- ments. With information from the models, a Regional class vessel can be used to deploy a fleet of AUVs and small moorings in a nearshore region where red tides are known to initiate, presumably by the resuspension of resting stages from the sediments into a growth environment. Once the resuspension event is detected, a shore-based command system that integrates observations, satellite data, and model information will instruct the AUVs to map the area with in situ sensors and to collect samples. Scientists aboard the ship can confirm that the samples contain target species, launch drifters to track the location of the HAB, and monitor the patch until it decays. Data collected during the experiment will provide a foundation for refining models and identifying critical observations to improve HAB prediction and mitigation.
FUTURE SCIENCE NEEDS 27 or Ocean class vessels capable of engaging in multi-investigator, complex experiments are needed. Smaller vessels will also be needed to study biogeochemical processes in shallow coastal waters. In the future, these nearshore, ship-based programs will be complemented by an array of sensors mounted on moorings and observatories. Ocean acidification is an important, growing area of research. Approx- imately 40 percent of the CO2 introduced into the atmosphere from burn- ing fossil fuels is being taken up by the ocean, affecting inorganic carbon equilibration and decreasing pH in the surface ocean (Sabine et al., 2004). It is currently unknown how this issue will affect ocean biodiversity, eco- system structure, productivity, and the dynamics of marine populations. Ship-based research will be necessary to determine how much carbon is being taken up, where it is being stored, and how it is impacting marine ecosystems. Much of this research can be done on Regional/Coastal and Regional class ships, while ocean basin-scale studies will require larger Ocean or Global class ships, particularly in regions with higher sea states (e.g., Labrador Sea). In shallower waters, Regional/Coastal vessels will continue to be needed to study the impact of ocean acidification on coral reefs. The role of climate change and anthropogenic pressures on marine populations and biodiversity is a crucial question. Programs such as Global Ocean Ecosystem Dynamics (GLOBEC) attempt to understand long-term, basin-scale variations in marine ecosystems through a combi- nation of process studies and food web modeling. In addition to sophisti- cated modeling efforts and ocean observatories with continuous data col- lection, technological drivers include acoustically quiet instrumentation and vessels that are able to effectively conduct fish stock and mammal research. These types of programs often require the use of multiple ships in different regions during overlapping time periods. Biological oceanography will continue to require manned submers- ibles and remotely operated vehicles for observation and sampling of deep sea and water column biota. These platforms are critical for sam- pling pelagic organisms in the midwater and for collecting organisms at the seafloor, including hydrothermal vent and methane seep communities and deep water corals. These communities are poorly known and cur- rently undersampled. At present the deep submergence community is in the process of replacing the human-occupied submersible Alvin and has developed a new hybrid remotely operated vehicle (ROV) for exploration of deep subduction zone trenches (Bowen et al., 2008). In 2004, a National Research Council (NRC) report recognized the need for a second ROV (National Research Council, 2004). Since submersible and ROV crews take up a significant number of science berths and require large deck areas,
28 SCIENCE AT SEA there will be considerable pressure to conduct these cruises from Global class ships in the future. Marine Geology Marine geology and geophysics (MGG) focuses on processes leading to the formation and evolution of the ocean crust and continental mar- gins and their linkages to processes in the Earthâs oceans, mantle, and continents. Although a significant component of research in MGG still involves exploration (National Research Council, 2003b), the past few decades have seen a general trend toward studies that integrate multi- disciplinary observations to understand complex systems. Major research areas include the following: â¢ Paleoceanography and paleoclimatology â¢ Formation, evolution, and destruction of oceanic crust and lithosphere â¢ Sedimentary processes on continental margins â¢ Role of crustal fluids in the geologic cycle (i.e., crustal alteration, hydrothermal systems and chemosynthetic life, earthquakes) â¢ Geohazards, including tsunami generation and gas hydrates. There is increased emphasis on MGG topics that are of immediate societal interest. Geological records are used in paleoceanography and paleoclimatology to understand processes that affect climate change and cause variability in the climate-ocean system on various time scales. Stud- ies of gas hydrate deposits on the continental margin are motivated by their potential as an energy source and by their role in carbon sequestra- tion. The 2004 Southeast Asian tsunami led to renewed studies of sub- duction zone earthquakes and the mechanisms of tsunami generation. Human occupation of the coastal zone drives continued need for process studies related to sediment resuspension and transport at the land-ocean interface and along the coastal margin. While sophisticated laboratory measurements and computer model- ing play an increasingly important role in MGG, research vessels remain an essential driver to explore the seafloor and underlying geological struc- tures, sample rocks and fluids on and below the seafloor, and deploy sea- floor instruments. Nearly every major research direction within MGG is at the forefront of utilizing new or improving observational and sampling technologies and thus requires research ships that are capable of using or deploying them. Seafloor mapping, a prerequisite for many multidisciplinary oceano- graphic studies (see Box 2-4), serves both as an exploratory tool and as
FUTURE SCIENCE NEEDS 29 Box 2-4 Carbon Cycling Observatories in the Arctic In this hypothetical example, a cabled observatory that has been deployed from Barrow, Alaska, to passively monitor bowhead whale migrations and methane seeps, as well as measure changes in the base of the ice canopy throughout the year using upward-looking sonars, is being expanded. The new observatory node will extend from the shelf to the base of the slope to measure organic carbon exchange in a changing Arctic Ocean. Placement of the new node will depend on identifying preferred sediment pathways by mapping regions where organic carbon is being deposited. Large-scale geomorphic features such as Barrow Canyon as well as smaller-scale features such as grooves and iceberg scours created by glaciogenic processes influence sediment pathways and deposition rates. A late- summer field geophysical mapping program will systematically collect multibeam and subbottom data for the region and then deploy an ROV for higher-resolution surveying and sampling of candidate sites. The ROV video system and sensors will simultaneously measure nutrients in the water and map macrofaunal benthic communities that could be affected along proposed cable pathways. Sediment samples will be collected and analyzed to estimate sedimentation rates for organic carbon using 210Pb and 137Cs. Satellite-derived images of ocean and ice canopy conditions will be beamed to the ice-strengthened vessel several times per day to provide advance warning of changing conditions and promote safe operations. a means to answer basic science questions about seafloor processes. All Global and Ocean class ships in the UNOLS fleet are equipped with deep- water multibeam systems for regional-scale mapping. AUVs are effective platforms for collecting high-resolution bathymetric, sidescan, magnetic, and gravity data and have been demonstrated to successfully comple- ment ship-based surveying for mapping at nested scales or as an add-on to cruises with other objectives. Seismic techniques are a critical component of MGG studies along active plate boundaries and rifted continental margins. In 2008, the University-National Oceanographic Laboratory System (UNOLS) fleet upgraded its capacity to accomplish seismic surveying with the Marcus Langseth, which is capable of deep penetration two- and three-dimen- sional multichannel reflection profiling. The air gun seismic source can also be used for ocean bottom seismometer refraction experiments. Given the importance of seismic imaging to MGG and ongoing developments of new computational tools and interpretive capabilities, it is likely that MGG will place high demands on the Marcus Langseth and other plat- forms capable of carrying out seismic surveys. Ocean bottom seismometers networks are increasingly being deployed
30 SCIENCE AT SEA for passive experiments to monitor microearthquakes along plate bound- aries and to image lithospheric and upper mantle structure using tele- seismic earthquakes. Plans for research in ocean mantle geodynamics (Oceanic Mantle Dynamics Workshop, 2002) envision an increased use of passive seismic arrays as well as the use of passive and active source electromagnetic experiments in combination with petrological and geo- chemical studies to understand the coupling between mantle convection and plate tectonics. All of these studies will require the largest ships in the UNOLS fleet for instrument deployment. Deep drilling provides a means to sample sedimentary and igneous rocks and pore fluids below the seafloor, to measure physical properties below the seafloor, and to monitor hydrological processes. In sedimentary environments, coring techniques complement drilling and are important for coastal and paleoceanographic studies. At present, the Integrated Ocean Drilling Program (IODP) provides riser and riserless platforms to support drilling, while the 2007 commissioning of the Woods Hole Oceanographic Institution (WHOI) long corer on the Knorr (Figure 2-2) provides the capability to collect cores up to 45 meters long (Curry et al., 2008) and represents a critical, heavily utilized tool for the paleoceano- graphic community. Despite significant community interest (Sager et al., 2003), the U.S. academic fleet currently has very limited capabilities for drilling short holes robotically in igneous and lithified sedimentary rocks. The development of such a system is anticipated to increase the demand for platforms that can carry out drilling and coring. MGG utilizes submersibles and ROVs for observational seafloor stud- Figure 2-2â The WHOI long corer system mounted on the R/V Knorr (used with permission from James Broda, Woods Hole Oceanographic Institution).
FUTURE SCIENCE NEEDS 31 Box 2-5 Volcanic Eruption on the Juan de Fuca Ridge In this hypothetical near-future scenario, the Ocean Observatories Initiative (OOI) regional cabled observatory deployed on the Juan de Fuca plate and the U.S. Navyâs Sound Surveillance System (SOSUS) hydrophone network detect a three-day swarm of earthquakes with the signature of a volcanic eruption on the southern Juan de Fuca Ridge. At the same time, sensors deployed around the nearest cabled node, 150 km to the north on Axial Seamount, detect high rates of local microearthquakes and increased fluid temperatures and flow rates in nearby hydrothermal vents. The mid-ocean ridge community mounts an event response cruise to better understand impacts of volcanic eruptions on chemosynthetic bio- logical communities, resolve a long-standing controversy on the origin of event plumes (hydrothermal plumes that rise 1 km above the seafloor soon after an eruption), and understand how a volcanic eruption triggers changes in seismicity and hydrothermal flow 150 km away. Within a week, a Global class ship equipped with an ROV reaches the eruption site. Telepresence allows several key scientists to participate from shore and shipboard scientists to stream live video of ROV operations to science museums and aquariums across North America. Despite challenging weather conditions, the scientists are able to explore the eruption site, collecting rocks and hydrothermal fluid samples for chemical and microbial analysis. Between ROV dives, the shipboard CTD detects and samples an event plume. Scientists are able to launch floats into the event plume, tracking its move- ments for future sampling. The ship then transits to the Axial Seamount cabled node, where the ROV replaces fluid samplers and sensors that have failed. Using samples collected during the cruise, the science party initiates a discussion with funding agencies regarding the feasibility of a follow-up cruise in 2 to 3 months. ies. They are necessary for multidisciplinary studies of hydrothermal systems (see Box 2-5), creating detailed geological maps, precise rock sampling and coring in complex terrain. In addition, they will continue to be essential for servicing instrumentsâfor example, to monitor fluid pres- sure, temperature, and chemistry in Ocean Drilling Program boreholes. The Ocean Observatories Initiative (OOI) has been motivated by the recognition that sustained time series observations are critical to many fields of oceanography. In MGG, observatories are necessary to char- acterize volcanic eruptions and large earthquakes and to monitor their impacts on fluid discharge across the seafloor and chemosynthetic bio- logical communities. These observatories will require significant Ocean and/or Global class ship time, with an ROV that is capable of deploying short runs of thin cable, junction boxes, and a wide variety of sensors.
32 SCIENCE AT SEA Oceanography education and training Addressing the future ocean sciences research agenda will require a cadre of well-trained seagoing scientists. Students need to gain experience and training at sea to become scientists that are well versed in the broad field of oceanography. Gaining experience at sea is nearly as crucial for future oceanographers who will do their work ashore as it is for those who will run ship-based research experiments, in whose case at-sea experience amounts to a type of apprenticeship.Â New technologies will enhance edu- cation on shore but are unlikely to change the paradigm. The academic fleet will need ships with sufficient berthing to carry not only the science and technical teams, but also the next generation of oceanographers. CONCLUSIONS The future ocean sciences research agenda will be driven by a diverse portfolio of disciplinary and interdisciplinary seagoing studies across a broad range of spatial and temporal observational scales. The fleet of the future will be required to support increasingly complex, multidisci- plinary, multi-investigator research projects using autonomous technolo- gies, ocean observing systems, remote sensing, and modeling. Research vessels will be needed to investigate and explore all areas of the ocean, from tidal zones to deep trenches. Recent advances in technology (such as global arrays of floats and satellite data) have fundamentally altered oceanographic research, with sampling coverage and frequency that far outweigh the collection abilities of the research fleet. However, several new technologies that will impact future ocean research (e.g., in situ chemical and genetic sensors) have not yet been proven capable of withstanding the rigors of deployment on a mooring, autonomous vehicle, or ocean observing system, and most of these systems will require both ship deployment and calibration. In the next 10-20 years, autonomous mobile platforms and fixed observatories are not expected to have sufficient sensing capabilities to replace tradi- tional research vessels. Ship-based measurements will continue to be required in the fore- seeable future to further both basic research and new discoveries in the ocean. A capable academic research fleet will continue to be required for needs such as water sampling, calibration and validation of satellite remote sensors, seafloor mapping and drilling, focused process studies, and atmospheric sampling. As continuous ocean observing systems and future generations of autonomous and fixed platforms document novel phenomena and processes in the ocean environment, they are likely to drive increased demand for ship time to research these new discover- ies further. Ships will also continue to be required to train students and advance the study of oceanography.