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SCIENTIFIC OBJECTIVES FOR ARCTIC RESEARCH

Understanding of critical global processes will be enhanced significantly by exploration and research in the Arctic. Scientific interests in the Arctic focus on:

  • the geology and history of the ocean basin and surrounding continental shelves;

  • world ocean circulation, affecting climate and global change;

  • chemical tracer and pollution studies; and

  • life histories of arctic species and food web structure of arctic communities.

In this chapter, priorities for marine sciences in the Arctic are presented in each of four subdisciplines: marine geology and geophysics, physical science, chemical oceanography, and biological science. Platforms needed for major scientific tasks are described. Although some individual research tasks might be conducted more efficiently by different platforms, a dedicated arctic research vessel is required for carrying out multidisciplinary research and collection of synoptic data sets for biological, chemical, and physical parameters. There are a variety of important multi- and interdisciplinary research topics, for example, studies of the effects of physical oceanography on the biology of marine organisms and the functioning of arctic ecosystems.



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ARCTIC OCEAN RESEARCH AND SUPPORTING FACILITIES: NATIONAL NEEDS AND GOALS 2 SCIENTIFIC OBJECTIVES FOR ARCTIC RESEARCH Understanding of critical global processes will be enhanced significantly by exploration and research in the Arctic. Scientific interests in the Arctic focus on: the geology and history of the ocean basin and surrounding continental shelves; world ocean circulation, affecting climate and global change; chemical tracer and pollution studies; and life histories of arctic species and food web structure of arctic communities. In this chapter, priorities for marine sciences in the Arctic are presented in each of four subdisciplines: marine geology and geophysics, physical science, chemical oceanography, and biological science. Platforms needed for major scientific tasks are described. Although some individual research tasks might be conducted more efficiently by different platforms, a dedicated arctic research vessel is required for carrying out multidisciplinary research and collection of synoptic data sets for biological, chemical, and physical parameters. There are a variety of important multi- and interdisciplinary research topics, for example, studies of the effects of physical oceanography on the biology of marine organisms and the functioning of arctic ecosystems.

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ARCTIC OCEAN RESEARCH AND SUPPORTING FACILITIES: NATIONAL NEEDS AND GOALS Marine Geology and Geophysics The scientific community has identified the following issues as having high and roughly equal priority in arctic marine geology and geophysics research: paleoceanography and the paleoclimatic record; dynamics of the spreading of the Nansen-Gakkel Ridge; tectonic evolution of the Amerasia Basin; and sediment dynamics on continental shelves and slopes. Paleoceanography and Paleoclimatology The fundamental objective of global change research is to develop an understanding of the ocean-atmosphere-land system to the extent that accurate predictions of both short- and long-term climate change can be made. These predictions are needed for translation into reliable information that will encourage better policymaking and planning. There is abundant evidence that significant variations in the ocean and climate systems have occurred on time scales of 100 to 1,000,000 years. Through analyses of deep-sea cores for a range of paleoceanographic proxies (e.g., isotopic ratios and abundances of diatom and foraminifera species), it is possible to construct three-dimensional pictures of the distribution and variation of oceanic properties at a number of previous time periods. In pursuit of improved predictive capabilities, a tremendous amount of effort has been devoted to developing coupled ocean-atmosphere-land climate models. These models have clearly demonstrated the sensitivity of the high-latitude northern regions to global-scale forcing (such as increases in atmospheric carbon dioxide (CO2)) and the role of northern regions in affecting the global climate system. Paleoclimatic and paleoceanographic data establishing past conditions must be used to test and validate climate model performance, yet the largest and most critical gap in global data is in the arctic region. The results of model simulations provide forcing functions that allow modelers to evaluate the response of the global climate system to major natural changes in conditions (for example, the unintended experiment provided by the 50 percent increase in atmospheric CO 2 associated with the last interglacial period). Characterization of past bottom currents and distributions of ice and its interaction with the seafloor are critical to the reconstruction of global climate, with application to predictions of future conditions. The type, size, and distribution of bottom bedforms on and beneath the seabed provide an extended record of arctic paleocurrents. Cooperative studies planned by German, Norwegian, and Russian scientists under the auspices of the International Arctic Science Committee will attempt to reconstruct ancient river discharges and their

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ARCTIC OCEAN RESEARCH AND SUPPORTING FACILITIES: NATIONAL NEEDS AND GOALS influence on sea-ice formation, stratification of surface waters, and productivity. The principal activities needed to reconstruct arctic paleoclimates are seafloor drilling and long coring to obtain continuous samples of sediment in areas where deposition is rapid and where erosion provides access to older sediments. The tops and flanks of ridges will provide the principal sites. Deep-sea drilling at even a few sites will increase our knowledge of climate cycles in the Arctic enormously. The Nansen Arctic Drilling (NAD) program has scheduled deep-sea drilling in the Laptev Sea and Lomonosov Ridge in 1996 and 1997 (Nansen Arctic Drilling Program, 1992). Selection of the best specific drill sites must be preceded by geophysical surveys that include swath mapping of bottom topography and seismic reflection profiling of subseafloor structure. In shallow slope and shelf areas multichannel seismic surveys are required, whereas in the deeper basins single-channel seismic surveys may suffice. The Arctic Mid-ocean Ridge The Arctic Mid-ocean (Nansen-Gakkel) Ridge is the slowest spreading major ridge segment on Earth and thus represents one of the extreme end-members of the global ridge system. Petrologists and geochemists are interested in studying the processes of magma generation and migration over the full range of ridge spreading rates. Ultra-slow spreading ridge segments are expected to have the greatest diversity of magma compositions because of the low magma budgets. The critical data needed to address this question are a high-resolution bathymetric map of the Arctic Mid-ocean Ridge using multibeam echo sounding. Dredging, coring, and drilling are required to obtain representative samples of igneous rock from outcrops on the ridge (Kristoffersen, 1990). Hydrothermal activity is a fundamental factor controlling seawater chemistry, and one of the most important processes linking the solid and the fluid realms. It is critical to determine the extent and distribution of hydrothermal venting over the slow end of the spreading rate spectrum. The spreading axis of the mid-Atlantic ridge system terminates on the margin of the Laptev Sea, which effectively places the Arctic Ocean portion, the Nansen-Gakkel Ridge, at the geographic end of the global mid-ocean ridge system. Vent communities in this area may support interactions between primary producers and consumers not previously observed. Observations regarding global biogeographic patterns of vent fauna distributions are critical to understanding processes that control evolution in the deep sea. The arctic seafloor is relatively free of seismic noise because surface gravity waves are absent. Thus, the ability to detect seismic signals with intermediate frequencies (10 Mhz to 1 Hz) could be enhanced by seafloor instruments in the Arctic. Knowledge of the Arctic Mid-ocean Ridge is limited, and understanding

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ARCTIC OCEAN RESEARCH AND SUPPORTING FACILITIES: NATIONAL NEEDS AND GOALS of its transition to an intracontinental plate boundary in eastern Siberia is important for understanding global plate tectonics. The resolution of tomographic profiles of the arctic ridges and basins would be improved with data obtained by seismometers deployed on the seafloor of the Arctic Ocean. Tectonic Evolution of the Amerasia Basin The Amerasia Basin is a large area of the world ocean for which useful, testable plate tectonic models are lacking. Until the location and kinematics of the several plates suspected to underlie the basin are established, the origin and tectonic assembly of the surrounding continents and extensive continental shelves will remain poorly understood. Systematic bathymetry, acoustic imaging, and gravity and magnetic potential field surveys of selected areas of the basin will provide important insights into its geological structure. Tectonic features such as the Neogene and Quaternary thrust faults and folds also locally deform the seabed in the Amerasia Basin, and their systematic delineation will contribute to our understanding of the plate tectonic geometry and kinematics of the basin. Extensive swath mapping of the major features in the Amerasia Basin together with comprehensive potential field measurements over the entire basin will provide the most important new insights into the tectonic evolution of the Amerasia Basin. Multi- and single-channel seismic profiling from icebreakers or submarines on selected targets is also a critical need to decipher the history of the basins and ridges. Coring, and ultimately deep-sea drilling, of selected targets will be needed to establish the chronology of the development of the basin. Sediment Dynamics on Continental Shelves and Slopes, Cross-Shelf Transport, and Shelf-to-Basin Transport The Arctic Ocean receives the largest riverine input relative to its volume of any major ocean. Most of this input is from Siberian rivers that empty into the Barents, Kara, Laptev, and East Siberian Seas. During the twentieth century, industrial development, nuclear weapons manufacturing, and nuclear fuel processing in the former Soviet Union along many of these rivers resulted in the introduction of large amounts of industrial and radioactive wastes onto the shelves that underlie these shallow seas. Prediction of the dispersal of pollutants into Arctic Ocean waters and ultimately into the world ocean requires an understanding of the extent to which industrial and nuclear pollutants are incorporated into arctic sediments and recycled into the water column during erosion and sediment transport. These pollutants present a potential environmental threat, but they can also be used as chemical tracers to track and quantify sources and

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ARCTIC OCEAN RESEARCH AND SUPPORTING FACILITIES: NATIONAL NEEDS AND GOALS dispersal pathways. A new environmental initiative is under way with a Russian/German program in the Laptev Sea and a Norwegian/Russian program in the Barents Sea. One of the primary objectives of this initiative is to quantify and characterize the supply of dissolved and particulate matter, and its accumulation on arctic continental shelves. Large areas of the Arctic Ocean shelves have significant resource potential. Areas such as the Laptev Sea are already being explored and developed for hydrocarbons. The geology of this drowned continental platform is known at only the most rudimentary level. Mapping the extent and stratigraphy of basins on the Eurasian and North American shelves will provide the fundamental framework for resource assessment as well as contribute to understanding the geology of this remote and difficult-to-access region of the world. The shallow stratigraphy of arctic continental shelves provides an opportunity to study the history of sea-level rise and fall in the Arctic Ocean in the Late Tertiary and Quaternary periods. High-resolution shallow-water seismic profiling, in combination with shallow-penetration sediment drilling and coring, will be the main tools for investigating the sediments of the shelves. Multichannel seismic and potential field surveys will be important for defining the deep interior structure of the arctic shelves. For investigation of deep channels and canyons on the arctic shelves and slopes, swath mapping and near-bottom imaging will be required. Some of this work was begun by surveying of the Bering Sea channels in the 1980s. Facilities Requirements Most of the objectives of marine geology and geophysics research do not require year-round access to the Arctic Ocean but could instead be pursued in summer when the ice cover is thinnest. An ARV could be used for swath mapping and for gravity, magnetic, and seismic surveys. However, the ideal vehicle for swath mapping, gravitational, and magnetic potential field measurements, and some seismic reflection work for the Arctic Ocean is the nuclear-powered submarine (SSN). The SSN has great endurance; it travels at speeds up to 25 knots and is intrinsically quiet and stable. Because it can operate under the ice, the SSN has access to all areas of the Arctic that are deeper than 100 m. An SSN could map the bathymetry, shallow subseafloor stratigraphy, and the magnetic and gravitational fields of large areas of the Arctic Ocean floor in a few years of concentrated effort (Table 1). Thus, a submarine is by far the most efficient and effective vehicle for precisely charting the bathymetry and gravity and magnetic fields of the Arctic Ocean basin. An NRC committee (NRC 1991, p. 53) believed that submarines would become the mainstay of geophysical data acquisition in the Arctic and recommended that “a national program to acquire multisensor geophysical data beneath the ice pack be considered. ” The report

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ARCTIC OCEAN RESEARCH AND SUPPORTING FACILITIES: NATIONAL NEEDS AND GOALS TABLE 1 Platform Requirements for Marine Geoscience Studies Measurement Resolution Spacing/ Coverage Study Area Platform Total Time (months)a Months per Year Swath mapping 10m 2 X depth all areas submarine 40 8 Gravity and magnetic surveys 1 mGal/1 nT 5 km all areas aircraft submarine 6/40b 1/9b Multichannel seismic surveys ca. 30 m — selected local lease icebreaker 15 1-2 Heat flow surveys 1 m W/m2 various selected icebreaker ice camp 10 1-2 Coring — various all icebreaker ice camp 10 1-2 Drilling — various selected mid-ocean areas leased arctic drilling platform 8 to 10 2 a The time-to-completion figures were estimated by members of the committee. For swath mapping, gravity and magnetic surveys, multichannel seismic surveys, and heat flow measurements, the estimates are based on the speed at which surveys can be conducted and the area of greatest interest to be surveyed, The coring and drilling values are based on the committee's best estimates of the number of holes needed to achieve science goals. b Depending on the choice of platform (aircraft or submarine survey).

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ARCTIC OCEAN RESEARCH AND SUPPORTING FACILITIES: NATIONAL NEEDS AND GOALS stated that the program would create a special niche for the United States in arctic solid-earth geoscience and produce major breakthroughs in scientific knowledge as well as economic returns to the United States. Gravity and magnetic fields can also be measured effectively from aircraft (Table 1). Large areas of the Amerasia Basin have already been mapped in this way by the geophysics group at the Naval Research Laboratory (Brozena et al., 1995). A partial map of the long-wavelength gravity field has been derived from satellite altimetry (Laxton and McAdoo, 1994). Dredging, coring, remotely operated vehicle (ROV) operation, heat flow measurements, seismic refraction, and multichannel seismic profiling are best done from a large surface platform, although some of these tasks could be accomplished from ice camps (Table 1). A research icebreaker could provide a surface platform in the margins of the Arctic Ocean during the summer season but would have to be escorted by an icebreaker that could navigate multiyear ice to work in the central Arctic Ocean. Alternatively, if an SSN can be used to conduct underway geophysical mapping, additional station work in the central Arctic could be done from ice camps. For work on the shelves, a relatively shallow-draft, ice-capable ship is required. Ice vehicles such as snowmobiles and hovercraft can be employed for station work through nearshore fast ice, though their uses are somewhat limited by rough ice conditions. In deeper waters, large research icebreakers such as the proposed ARV or Healy could provide access from July to October, or throughout most of the year if escorted by more powerful icebreakers. Deep-sea drilling in the Arctic presents special problems that have been addressed in detail by the NAD program (NAD Program, 1992). It seems most efficient to charter or lease drilling platforms that are already in the Arctic or can be easily transported there (Table 1). Existing scientific drilling vessels such as the JOIDES Resolution operated by Texas A&M University for the Ocean Drilling Program, could be used near the ice margin if escorted by a powerful icebreaker. Physical Oceanography, Climate, and Sea Ice The report from NSF's community workshop of March 1990 at Lake Arrowhead, California, on Arctic System Science “Ocean-Atmosphere-Ice Interactions” (Moritz et al., 1990) identifies and discusses important research themes and needs in arctic physical science. That report succinctly defined and set priorities for national science needs in the marine Arctic for the next decade and beyond. Together with the results of the Arctic Science Symposium (March 28-30, 1995) and the Regional Research Programme in the Arctic on Global Change (IASC and NRC, 1994), the Moritz et al. report suggests three primary

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ARCTIC OCEAN RESEARCH AND SUPPORTING FACILITIES: NATIONAL NEEDS AND GOALS research directions in relation to studies of physical oceanography, climate, and sea ice: circulation, mixing, and water mass transformations; surface energy budget, atmospheric radiation, and clouds; and freshwater and ice balance. Similar themes emerged from the European Committee on Ocean and Polar Sciences conference held in September 1994 (Johannessen et al., 1994). A coordinated research effort will be needed to address these topics. This effort will necessarily involve three different approaches to acquiring data: large-scale surveys, time-series monitoring, and process studies. Each of these approaches has different facilities requirements related to the location, time, and space scales to be sampled. Circulation, Mixing, and Water Mass Transformations Model simulations of global change that include ocean-atmosphere-land-ice interactions predict a particularly large increase of surface air temperature and marked reduction of sea ice cover over the Arctic Ocean in response to perturbations such as increased CO2 concentration in the atmosphere (Manabe and Stouffer, 1994). These models also predict large increases in precipitation in high latitudes of the Northern Hemisphere and substantial weakening of the thermohaline circulation, which would moderate the warming over the northern North Atlantic Ocean and Western Europe (Manabe and Stouffer, 1994). In all global models, the dynamics and thermodynamics of sea ice exert primary control on the simulated climate response of the Arctic and Antarctic (Clark, 1982). There are wide variations among models, however, in both the formulation of the relevant ice processes and in the quantitative sensitivity of polar climate to perturbations. It is clear that the mechanisms controlling the thermohaline circulation in the Arctic need to be understood better. To understand the circulation, mixing, and water mass transformations in the Arctic, five main tasks must be accomplished: assess the large-scale circulation and its role in the maintenance of the hydrographic structure and ice cover (IASC and NRC, 1994); investigate the interactions between the shelves and the deep basins (NRC, 1988); estimate the exchanges between the Arctic Ocean and the seas to the south (NRC, 1988); assess the influence of sea ice on arctic circulation (Johannessen et al., 1994); and

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ARCTIC OCEAN RESEARCH AND SUPPORTING FACILITIES: NATIONAL NEEDS AND GOALS understand the principal dynamics of arctic circulation (Johannessen et al., 1994). An event that began in the late 1960s with a pulse of fresh water into the ocean north of Iceland illustrates how sustained changes in relatively small ocean regions can conceivably change the thermohaline circulation of the Arctic Ocean. This “Great Salinity Anomaly” circulated around the Atlantic Ocean and returned to the Greenland Sea via the Atlantic Water inflow through the Faeroe-Shetland Channel, where it stopped deep water formation (Dickson et al., 1988; Aagaard and Carmack, 1989). Winter convection in this area now reaches only a third of the way to the seafloor, isolating the dense waters underneath and resulting in changes whose long-term impacts are only beginning to be comprehended. Recent studies indicate another event that occurred at the winter sea surface outside the Arctic Ocean and resulted in a thickening and one-half degree warming of the Atlantic Layer in the Arctic Ocean interior.* This thickening and warming, which has been described as a broad and deep anomaly of temperature and salinity, was detected from measurements conducted during two recent large-scale surveys: the SciCex-93 submarine cruise (Langseth et al., 1994) and the Arctic Ocean Section 1994-1995 (Travis, 1994). Without a baseline assessment of the oceanography of the Arctic, it will be difficult or impossible to assess the impact of such changes on arctic and global thermohaline circulation, whether or not they are indicators of climatic variability in the system. A major part of this assessment can be accomplished through large-scale surveys, and much has been accomplished by Russian investigators in the past 25 years. Throughout much of the central Arctic Ocean, important time and space scales increase with depth, suggesting that repeat surveys of properties through the full water column may be needed only once per decade, whereas surveys of some near-surface properties will be needed more frequently. Time-series measurements of a large suite of parameters are needed to resolve variability on time scales of days to years to decades. Characterizing variability is essential to assess the representativeness of the surveys and to resolve processes such as mixing, mesoscale circulation, and the salinization and freshening of the water column associated with the freezing and melting of ice, respectively. New techniques using acoustic thermometry and tomography can provide year-round synoptic monitoring of potential value to climate research in the Arctic Basin using acoustic propagation paths that crisscross the Arctic. Low-frequency sound (below 90 Hz to minimize scattering) can be used for monitor- * James Swift, Scripps Institution of Oceanography, and James Morison, University of Washington, personal communication to the committee, March 28, 1995.

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ARCTIC OCEAN RESEARCH AND SUPPORTING FACILITIES: NATIONAL NEEDS AND GOALS ing changes in temperature and salinity in the central Arctic Ocean to support climate studies and monitor global climate change. In the marginal seas and over shorter distances, frequencies in the 100 to 200 Hz range can be used to monitor ocean temperature changes and fluxes, as well as heat transport in the Fram Strait and other entrances to and exits from the Arctic Ocean. Acoustic thermometry can be conducted year-round over the entire Arctic, and provides information about the Arctic Ocean that is unavailable from satellites or ships because of the ice cover. Concurrent conductivity-temperature-depth/sound velocity profile (CTD/SVP) measurements are necessary in the early phases of this work to provide ground-truthing for understanding and interpreting the acoustic results. The research will focus on understanding the interaction between acoustic and oceanographic factors in four dimensions and characterize Arctic Ocean processes and their effects on the acoustics from internal wave scales (at frequencies higher than 100 Hz) through mesoscale and gyre scales. Processes at every scale are important to climate-related oceanography. Experiments must eventually encompass the spectrum from large-scale circulation, to fronts and mesoscale eddies, to small-scale turbulence and mixing. These experiments will require multibasin deep sections, acoustic tomography and thermometry, shelf surveys, clever use of moorings and subsurface floats, and rapid profiling of mesoscale, fine-scale, and microscale features. Surface Energy Balance, Atmospheric Radiation, and Clouds The radiation balance dominates the energy budget of the Arctic Ocean 's surface in all seasons, and also plays a major role in the climate feedbacks exhibited by global climate models. These feedbacks involve strong interactions between surface radiative fluxes and the energy and mass balance of the sea ice and snow cover. Clouds are difficult to simulate in climate models. Cloud observational data in the Arctic are inadequate because there are few surface meteorological stations, particularly in the pack ice, and because cloud detection algorithms applied to satellite measurements perform poorly in this area. The recent climate record seems to show little or no observable manifestation of ice-snow-cloud-radiation feedback (Untersteiner, 1990), even though the poleward amplification of temperature change predicted with increased greenhouse gases is generally ascribed to this feedback. Furthermore, the results from different climate models vary widely. Comparative analyses of these results indicate that the concept of a straightforward albedo feedback based on net shortwave radiation is too simplistic, and that interactions with longwave radiation and hence clouds must be included at the same time (Untersteiner, 1990). To address the important processes that affect the Arctic's role in global

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ARCTIC OCEAN RESEARCH AND SUPPORTING FACILITIES: NATIONAL NEEDS AND GOALS climate requires coordinated process studies that (1) observe the interactions among the ice and snow cover, atmospheric forcing, clouds, and the arctic mixed layer over at least a full annual cycle, and (2) define feasible measurement strategies for monitoring the state of the arctic climate over the coming decades. In addition to the process studies, emphasis should be given to measurements that will establish an accurate surface radiation budget climatology for the Arctic Ocean. It is also important to conduct careful and precise comparisons between satellite measurements and in situ data and to develop more accurate observational determinations of key variables needed for model simulations of ice coverage. Most of the needed in situ observations can be obtained as part of the largescale surveys and process studies discussed above or by the establishment of ground-or ice-based monitoring stations at high-latitude locations or by means of aircraft surveys. Freshwater and Ice Balance The Arctic Ocean may be thought of as a giant estuary that receives fresh water in the form of (1) runoff from Eurasia and North America, (2) precipitation (minus evaporation), mainly in the form of snow that accumulates atop sea ice during winter, and (3) low-salinity inflow through the Bering Strait. Much of this freshwater input is balanced by the export of sea ice and low-salinity arctic surface water at the Fram Strait. However, based on recent data,† it is apparent that at least some ice grounded on Russian shelves (tagged with radioactive sediments) may continue to circulate in the Arctic Ocean without exiting. Disposition of exported fresh water appears to play a major role in controlling the thermohaline circulation of the North Atlantic Ocean. This is because at low temperatures, the stratification of the water column is predominantly determined by salinity. This freshwater balance results in a strong halocline within the Arctic Ocean. Without this strong halocline, the ice cover might disappear, with enormous climatic, environmental, and economic consequences. In addition to the process studies described in preceding sections, it is important to monitor the inputs, reservoirs, and outputs of this freshwater cycle. A combination of observational and modeling activities is needed to refine the estimates of the large-scale hydrological cycle. The types of data needed include atmospheric moisture flux into the basin, river runoff, mass balance of sea ice, and changes of the water mass characteristics of the Arctic Ocean and † Walter Tucker, U.S. Army Cold Regions Research and Engineering Laboratory, personal communication to committee, February 22, 1995.

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ARCTIC OCEAN RESEARCH AND SUPPORTING FACILITIES: NATIONAL NEEDS AND GOALS allow determination of pathways of near-surface waters into the interior of the basins (tritium and chlorofluorocarbons (CFCs)) and provide information about the rates of deep water formation and interbasin exchange (tritium, CFCs, carbon 14, argon 39) and on the sources and residence times of fresh water entering the Arctic Ocean. Freshwater input can result from ice melting as well as fluvial inflow. The contribution of these two processes can be resolved using measurements of oxygen isotopes (or barium/nutrient concentrations) in conjunction with salinity, CFC, or tritium measurements. To understand water mass properties in the Arctic it is also necessary to acquire knowledge of halocline and brine formation. The halocline is a vital feature in the Arctic because it keeps the warmer waters at depth from surfacing, thus inhibiting ice melting at the surface. Because approximately half of the world ocean's abyssal waters originate in and around the Arctic, the importance of understanding deep water formation in the Arctic cannot be overemphasized. A recent analysis of tritium/helium 3 and CFC tracers has indicated a considerable slowdown in the formation of Greenland Sea Deep Water during the 1980s (Schlosser et al., 1991). Pollutants Pollutants in the Arctic may take the form of industrial waste (e.g., heavy metals and pesticides) coming down the major rivers of Asia, Europe, and North America or airborne materials transported through the atmosphere. They also may be in the form of radioactive waste leaking from subsurface storage through ground waters, rivers, or the seafloor. The Russian government admitted in 1993 that radioactive wastes, including submarine reactor cores, irradiated submarine cooling water, and even nuclear-tipped torpedoes, had been dumped or lost in the Arctic and North Pacific oceans (Government Commission on Matters Related to Radioactive Waste Disposal at Sea, 1993). Some of these pollutants will remain dissolved during their aqueous transport from the continents to the ocean (e.g., strontium 90), whereas others may be scavenged from solution by particles in the soil, rivers, or the ocean (e.g., lead or plutonium). An understanding of the pathways and fates of these pollutants in the oceanic realm in terms of particle scavenging and burial is essential for predicting their effect on marine ecosystems and ultimately biological resources. The fate of pollutants in the Arctic will depend on surface water residence time, particle flux, the reactivity of the pollutant, and exchange rates between surface water and deep water. The more soluble pollutants may exit the Arctic Ocean in surface water, whereas the particle-reactive species may be transported to depth by particle scavenging or by sediment resuspension across the shelf break. Continental slope deposits in the Arctic are a likely sink for these pollutants, but minimal data exist to address this hypothesis.

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ARCTIC OCEAN RESEARCH AND SUPPORTING FACILITIES: NATIONAL NEEDS AND GOALS Paleoceanography and Paleoclimate The feedbacks among controls of sea surface temperature and ice/snow cover serve to amplify the effects of these controls at high latitudes. The high-latitude climate, in turn, affects the pole-to-equator energy transfer and hence atmospheric circulation. Thus, the Arctic is a critical region for understanding global climate change. Knowing the range of conditions that existed in the past should help in understanding present and future climates. Unfortunately, little is known about past oceanic and sedimentary processes in the Arctic Ocean. Sediment cores collected in the Arctic can be used to evaluate variations in surface nutrient levels (caused by changes in circulation and riverine input), depositional processes, and ice cover history over the past few million years. A variety of chemical proxies (e.g., stable isotopes of oxygen and carbon; elemental ratios of cadmium/calcium and barium/aluminum; and activities of thorium 230/protactinium 231 and beryllium 10/aluminum 26) can be employed to reveal changes in ice cover history, sea surface temperature, and productivity. The results will enable correlations to be made between the marine record and records from the Greenland Ice Sheet Project (GISPII) and the Paleoclimate of Arctic Lakes and Estuaries (PALE) project as well as extend the record back to a time without ice and with high global concentrations of CO2 in the atmosphere. Facilities Requirements The Arctic presents a diverse environment in both space and time. Extensive sampling during all seasons is necessary to characterize the chemistry of the system. To address all of the research priorities described above requires facilities that enable research in continental shelf and slope environments, as well as in the deep central basins (Table 3). To sample these diverse environments in a systematic way and understand the relevant chemical oceanographic processes occurring in them, several months per year of ship time will be needed over a 10- to 30-year period. On these cruises the primary focus of the research would be chemical oceanography, although complementary science in other disciplines could be conducted as well. In addition, chemical oceanographers are expected to participate in most other research cruises to the Arctic to provide supplemental data to biological, physical, and geological research programs. An icebreaking research vessel is the most versatile platform from which to conduct the necessary field operations for chemical oceanography research priorities. This platform is essential because it permits a variety of sampling requirements to be carried out, including collection of water column profiles of dissolved and suspended chemical species, large-volume sampling and processing of trace metals and isotopes, coring, and deployment and recovery of instru-

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ARCTIC OCEAN RESEARCH AND SUPPORTING FACILITIES: NATIONAL NEEDS AND GOALS TABLE 3 Platform Requirements for Chemical Oceanographic Studies Measurement Resolution Spacing/ coverage Study area Platform Total time (months) Months per year Geochemical sampling (biogeochemical and pollutant) 1-100km 0.1-100m mostly shelves icebreaker ice camp 50 12 Water movement (tracers) 10-100m l-1000km basinwide icebreaker 20 6 Sediment coring 1-10cm 2-1000km basinwide icebreaker 30 2-4

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ARCTIC OCEAN RESEARCH AND SUPPORTING FACILITIES: NATIONAL NEEDS AND GOALS mented moorings, sediment traps, and benthic chambers. A research icebreaker is of highest priority because it accommodates a variety of sampling methods and provides enough space for multidisciplinary research, as well as access to the necessary arctic environments. Ice camps also serve as important platforms in meeting chemical research priorities in the Arctic. Ice camps permit data to be collected in different seasons (over several years in some cases) in a more or less time-series mode. However, the movement of ice camps with drifting surface ice may be decoupled from movement of bottom waters (which may move in different directions and at different speeds than the surface currents). Field camps located on land have been, and will continue to be, used to conduct research programs in the Arctic. However, most of this research is restricted to coastal environments because of logistic constraints of vehicles and vessels. Submarines have limited utility as platforms for chemical oceanography research. Although they are useful for surveying the upper halocline (current depth limits are 800 m), priority research objectives require a more versatile sampling platform. Of particular concern is the limited space on board submarines, which prevents much of the necessary chemical processing (requiring substantial equipment) and storage of a large number of samples. Furthermore, the restrictions on the use of certain organic solvents and radioactive materials on board submarines prevent certain types of chemical research from taking place there. Moorings and satellites are useful tools for chemical oceanographic needs in general; certainly they are for arctic investigations as well. Satellites are useful for chemical oceanography primarily because of their ability to provide information about physical and biological factors that affect ocean chemistry. Communication satellites also relay data from arctic-based instruments. These tools are complementary and supplementary to the platforms mentioned above and will not eliminate the need for other platforms. Biological Sciences Biological research in the Arctic can be divided into process-oriented studies of the origins and fates of organic carbon and species-oriented studies of fish, birds, and mammals. Because the requirements of these two approaches differ somewhat, each approach is discussed separately. Origins and Fates of Organic Carbon Contributions of primary producers, and consumption and transformations by heterotrophic organisms in the Arctic, vary along gradients in time, depth,

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ARCTIC OCEAN RESEARCH AND SUPPORTING FACILITIES: NATIONAL NEEDS AND GOALS and distance across the shelf to the deep basin. Past studies have suggested that rates of primary production in the Arctic Basin are not high enough to account for observed levels of particulate organic carbon (POC) and dissolved organic carbon (DOC), nor of observed secondary production in some arctic shelf/slope regions. Entrainment of plant detritus from adjacent shelves must occur to account for the observed levels (Subba Rao and Platt, 1984; Walsh, 1989, 1995; Pomeroy et al., 1990). Results from a recent trans-Arctic cruise, however, showed high bacterial production late in the season and high zooplankton standing stock in comparison with primary production levels. These higher levels are attributed to use of DOC left over from an earlier phytoplankton bloom.‡ These data suggest that in situ production in the high Arctic is great enough to explain POC, DOC, and zooplankton levels in comparison with shelf/slope regions. Several testable hypotheses could drive future research in accounting for the discrepancy between these two sets of observations: riverine input of POC and DOC; transport of POC and DOC from the Arctic shelf to the basin; and a temporal discontinuity between the peak of primary production and the resulting secondary production. Whatever the cause, the discrepancy suggests that the continental shelves and central Arctic may be decoupled in their carbon production and use. In particular, the central Arctic may uniquely depend on the microbial food web as a link between primary production and higher trophic levels. That is, primary production may not be consumed directly but rather may contribute to increased concentrations of organic material that is consumed by smaller and then larger heterotrophic organisms. However, the microbial loop becomes less important on the more productive shelves of the arctic marginal seas (e.g., Bering and Barents seas), where phytodetritus is more directly coupled to the underlying benthos (Grebmeier and Barry, 1991). The accumulation of carbon in fauna and sediments of the arctic slopes is possible but has not been studied. Future biological studies in the Arctic should define locations and rates of primary production and secondary consumer populations (both water column and benthic). Sources and fates of DOC and POC need to be determined. The structure of the arctic food web should be elucidated, and rates of carbon exchange along these trophic pathways should be measured. These questions are especially important in the Arctic, because the Atlantic deep water that supplies the world' s oceans forms in the Arctic, in the vicinity of Spitzbergen (Svalbard). Thus, this region may potentially serve as a significant carbon sink (Broecker ‡ Patricia Wheeler, Oregon State University, personal communication to the committee, March 28, 1995.

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ARCTIC OCEAN RESEARCH AND SUPPORTING FACILITIES: NATIONAL NEEDS AND GOALS and Peng, 1992; Sarmiento and Sundquist, 1992; Walsh, 1995). If ice cover decreases, the broad continental shelves of both the Siberian seas (including the Chukchi, East Siberian, Laptev, and Kara Seas) and the Barents Sea may provide an increased carbon sink. Knowledge of the origins and fates of carbon in the Arctic thus becomes essential for accurate modeling of global carbon flux. The Bering Sea is the location of one of the world's richest fisheries, although various important commercial fish species have declined over the past few decades (NRC, 1995). Protective management of Bering Sea fisheries may depend on an understanding of the underlying trophic structure of the commercially valuable fish species throughout all seasons, including the ice-covered winter months (NRC, 1995). Fish, Birds, and Mammals Vertebrate species in the Arctic are less studied than related temperate-zone species. Yet similar species at lower latitudes often serve as indicators of ecosystem stability, and with increased knowledge high-latitude species could serve a similar function in the Arctic (NRC, 1995). Arctic vertebrates are an important food source for indigenous peoples. Increasingly, birds and mammals are a focus for a developing arctic tourism industry (NRC, 1988). Although most are relatively plentiful, a few species are rare or endangered. Populations of arctic birds and mammals are closely linked with fish populations; therefore, studies of the interactions among fish, birds, and mammals are needed. Future vertebrate research is likely to focus on the following questions: Basic biology and life history: What are the basic annual events in the life history of these species? What are their physiological needs and constraints? Population-based questions: What are the genetic structures of the species (heterozygosity/stock separation)? What are the population sizes and structures (age/sex/breeding condition)? What are the trends in population sizes? Habitat-based questions: What are the habitat uses, especially in winter, for which little information is available? What are the temporal and spatial variabilities in habitat use? Environmental and oceanographic questions: What are the influences of environmental and oceanographic conditions on distribution patterns and behaviors? What factors affect recruitment success? Ecosystem interactions: What are the relationships among species? What are the trophic relationships? How important are forage fish in providing for sustainable commercial fisheries?

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ARCTIC OCEAN RESEARCH AND SUPPORTING FACILITIES: NATIONAL NEEDS AND GOALS Questions based on human interactions: How do populations of marine vertebrates affect human populations in the Arctic? How do human activities such as hunting/fishing, tourism, mining, and military activities affect these species? Facilities Requirements Sample collection methods used in research to answer the biological questions described in the previous section include water bottles or pumps (usually mounted with a conductivity-temperature-depth sampler) to collect smaller, soft-bodied organisms; plankton nets of various meshes, towed horizontally or vertically, to collect nekton and larger plankton; and grabs, trawls, and box and gravity cores to collect benthic samples (Table 4). These techniques require the use of a winch, and usually some ability to move horizontally. In situ experiments require moored or benthic chambers. Many techniques use radioisotopes. Sample analysis requires availability of laboratory space to hold controlled temperature chambers, fluorometers, spectrophotometers, centrifuges, scintillation counters, drying ovens, carbon-hydrogen-nitrogen analyzers, autoanalyzers, various types of microscales and particle counters, and specialized equipment. These items must be transported to the site, which implies a moving laboratory or an ability to transport delicate yet heavy equipment. Because most biological data require interpretation relative to physical and chemical parameters of the environment, biological oceanographers prefer to work in multidisciplinary teams, suggesting a requirement for relatively large scientific parties. An icebreaking research vessel would provide good spatial coverage, although access would be limited in the high arctic shelf and basin during part of the year, based on icebreaking capability. Sampling flexibility, laboratory space, and instrument transport would be excellent. A large interdisciplinary team could be accommodated. The ability to carry out seasonal or long-term temporal studies could provide scheduling challenges in certain geographic regions. Although a research icebreaker can provide a comprehensive platform for most biological oceanographic field requirements in the Arctic, some of these needs can be met, at least in part, by platforms other than a surface research icebreaker. If sufficient equipment and personnel can be transported, ice camps may provide opportunities for temporal studies at a single location. The most serious limitations include inability to move sampling equipment horizontally and lack of spatial coverage. Submarines could provide good opportunities for mapping of biologically important properties, using acoustics, fluorescence, turbidity, and other sensors. Collection of water samples is possible, although analytical laboratory space

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ARCTIC OCEAN RESEARCH AND SUPPORTING FACILITIES: NATIONAL NEEDS AND GOALS TABLE 4 Platform Requirements for Biological Studies Measurement Resolution Spacing/ coverage Study area Platform Total time Months per year Environmental/habitat parameters 100-1000m 5-50km basinwide icebreaker submarine ice camps decades 12 POC/DOC sources and fates 10-100 m 100-1000m basinwide icebreaker decades 12 Population surveys 10-100 m 1-10 km basinwide icebreaker ice camps decades 12 Population sampling 100-1000m 1-10km basinwide icebreaker decades 10-12

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ARCTIC OCEAN RESEARCH AND SUPPORTING FACILITIES: NATIONAL NEEDS AND GOALS would be limited. Other types of sample collection would require development and deployment of specialized collection equipment. Submarines are excluded from work in the shallow waters of the continental shelf, and thus are limited to the Arctic Basin. Permission to use radioisotopes would be required. Bunk space is limited, hence multidisciplinary studies would be constrained. Because arctic vertebrate species inhabit the sea, the surface of the land or ice cover, and the air, it is not surprising that research methods and facilities requirements for vertebrate research vary widely. Direct visual observations of terrestrial species (or those that breed terrestrially) require access within visual range. Close range is also required to obtain biopsy material and to tag animals. Subsequent use of biopsy material for genetic or pollution studies requires easy access to a well-equipped laboratory. Fisheries assessments generally require large nets and hook-and-line. Both are towed horizontally. They provide abundance estimates as well as material (fish) for basic life history data. Biosonics and remotely sensed visual information can be used to determine the spatial or temporal extent of assessment information, but generally some ground-truthing is required because the remote information is seldom species specific. As with birds and mammals, animal tissue is required for studying the genetic structure of a population or for tracing contamination along a food chain. Analysis of tissue samples requires access to a well-equipped laboratory. Facilities needs, like those of the carbon-based studies described earlier, can best be met with a variety of platforms. Some types of research would require a research icebreaker; some could use other types of platforms. Ice camps can give good access to terrestrial mammals and breeding birds for direct observations, tagging, and collection of biopsy materials. Ice camps also provide a laboratory base and can accommodate large, interdisciplinary research teams. Biosonic studies can be conducted from submarines. However, only a research icebreaker could provide: a platform for the large trawls and long lines required for fisheries assessments or as a launching platform for submersibles; access to marine birds and mammals that associate along the edges of the ice pack, where conditions are too unstable for an ice camp; and > the mobility needed to study the dynamics of vertebrate predator and prey interactions. Summary of Disciplinary Preferences for Research Platforms As described in previous sections, different disciplines have needs for different types of arctic research platforms. Table 5 shows preferences for different platforms, according to discipline.

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ARCTIC OCEAN RESEARCH AND SUPPORTING FACILITIES: NATIONAL NEEDS AND GOALS Studies in marine geology and geophysics need a platform that can rapidly cover large areas of the Arctic Basin, with facilities for swath mapping, echo sounding, and gravity, magnetic, and seismic profiling. The best research platform for these tasks is a nuclear-powered submarine. For station work such as use of remotely operated vehicles, heat flow measurements, and dredging, as well as work in shallower areas, a large research icebreaker is required. The need of a large surface ship capable of deep-sea drilling could be met by leasing an existing drilling vessel. TABLE 5 Platform Preferences of Marine Science Disciplinesa Platform Marine geology and geophysics Physical science Chemical oceanography Biological science Icebreaker + + + +b + + + + + + Submarine + + + + + + + + Moored instrumentation + + + + + + + + Satellites (remote sensing) + +b + + Aircraft survey + + + + + Drifting buoys 0 + +b + + Ice camps + + + + + + + Strongly preferred platform for most tasks + + Necessary platform for certain tasks, but not sufficient for all tasks + Useful platform as supplement 0 Little or no use in discipline a Preferences do not account for differences in capital or operating costs. b For sea ice and climate studies, satellites, aircraft, and drifting buoys are important research platforms, and a research icebreaker is useful to collect ground-truthing data. For physical oceanographic needs, several different types of platforms are needed, to collect data at several scales. Much use can be made of moored in-

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ARCTIC OCEAN RESEARCH AND SUPPORTING FACILITIES: NATIONAL NEEDS AND GOALS strumentation, buoys, drifters, and arrays that are left for long periods on the seafloor, in the water, or in ice. Submarines could contribute to the measurement of salinity and temperature in the deep Arctic Ocean. However, a surface icebreaker is needed to support interdisciplinary process studies and detailed vertical profiling of the water column in selected locations. Climate studies rely heavily on satellite remote sensing and ice-borne data buoys. Sea ice studies also use ice-borne data buoys. Submarines could contribute to mapping sea ice thickness, and aircraft are useful both to survey the ice and to transport scientists to selected locations for short-term measurements. Ice camps provide opportunities for longer time-series measurements and for ocean-atmosphere-ice process studies that must be conducted over a full annual cycle. For climate studies, a research icebreaker is a lower priority. Chemical and biological oceanography, as well as marine biology, have more specific needs for a large surface icebreaker to serve as a floating laboratory, process large volumes of water or tow large trawl nets, and carry large instruments to a study site. Interdisciplinary research would be supported best with the larger scientific crew possible on a research icebreaker. Some studies of vertebrates also require ice camps. Submarines, moored instrumentation, remote sensing, and ice camps could provide supplementary data but would not eliminate the need for a large surface ship.