Western Arctic Shelf-Basin Interactions (SBI) Project

Phase One
Principal Investigators Meeting

March 21-22, 2000

Baltimore Holiday Inner Hotel-Inner Harbor



Sponsored by the
National Science Foundation
Arctic System Science Program

Grebmeier,J. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
Harvey and and L.L. Belicka . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
Kadko,D. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
Markus, T. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
Maslowski, W. and R.W. Garwood . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
Mclaughlin, F. et al. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
Plueddemann, A . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16

Spitz, Y. H. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
Stamnes, K. et al. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
Weingartner, T. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
Wheeler, P. and Y. H. Spitz . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
Whitehead, J. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
Woodgate, R. and K. Aagaard . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .24

Summary speakers TBD and discussion session

1600 Meeting adjourns and return to hotel

Knut Aagaard

Polar Science Center – APL, University of Washington , 1013 NE 40th St., Seattle , WA 98105-6698

Tom Weingartner

Institute of Marine Science , University of Alaska Fairbanks , Fairbanks, AK 99775-7220

In support of the SBI initiative we propose a two-year analysis and synthesis of over 150 instrument years of time series measurements (primarily of velocity, temperature, and salinity) from selected portions of the arctic shelves, slopes, and adjacent deep basins. Our intent is to:
1) Provide an observationally based indication of the variability of the shelf-basin system, with an emphasis on the Western Arctic;
2) Contribute to focusing and refining the field programs planned under Phase II of SBI, particularly as these depend upon an understanding of the mechanisms of shelf-basin exchange, and upon the climatology and variability of the shelf-slope-basin system; and
3) Promote further improvements in the rapidly growing array of models of arctic circulation and hydrographic structures and their variability, and provide patterns and statistics against which to test the fidelity of these models. While the emphasis is on time series, we will also take advantage of the large hydrographic data base now available.

The geographic coverage of the already assembled data set includes the Western Arctic shelves, the continental slope and ridges in both the Eurasian and Canadian basins, and the Canada Basin abyssal plain. The intended synthesis will cover the circulation and its variability, with an emphasis on the statistics of the measured flows and their temperature and salinity, together with the dynamics that these statistics imply. We will also make this data set widely available through the National Snow and Ice Data Center, Boulder, likely via CD ROM.

The proposed retrospective study takes advantage of a large data set, the coordinated analysis of which will substantially improve our understanding of the circulation and hydrographic structures of the Arctic shelf-slope-basin system, including their links and variability. The effort will specifically contribute to the SBI initiative by addressing:
1) The variability of Western Arctic shelf sources for the interior ocean and the causes of that variability;
2) The principal mechanisms of exchange across the shelf and slope, likely together with bounds on the effective rates;
3) The background circulation over the shelf, slope, and adjacent abyssal plain and their relation to shelf-basin exchanges;
4) Secondary circulations over the outer shelf and slope and their variability; and
5) Freshwater processing and transport on the shelf.

The synthesis will further contribute to the development of improved models; it will constrain tracer interpretations and dynamical hypotheses; it will aid in the analysis of other data sets, including portions of the SHEBA data; and it will help provide a Pan-Arctic perspective for the SBI initiative.


MODELING THE FORMATION AND OFFSHORE TRANSPORT OF DENSE SHELF WATER FROM HIGH-LATITUDE COASTAL POLYNYAS

David C. Chapman and Glen Gawarkiewicz

Woods Hole Oceanographic Institution, Woods Hole, MA 02543

We propose to study the processes involved in the formation and offshore transport of dense water formed in high-latitude coastal polynyas. Our hypothesis is that dense water, formed in coastal polynyas, is transported across the shelf via small-scale (15-25 km) eddies. These dense-water eddies are potentially capable of moving offshore across the shelf break and into the deep basins where they contribute to the maintenance of the observed thermohaline structure. This hypothesis is based on our previous process modelling in which we developed simple formulas for water mass characteristics formed within a coastal polynya as a function of polynya geometry (essentially open water area) and the negative surface buoyancy flux (ice production).

We propose to test our hypothesis with:

1. Process-oriented numerical modeling: We will extend our idealized models to include ambient alongshelf currents and wind forcing. This will improve our understanding of the dynamical processes and our ability to model realistic situations.

2. Realistic numerical modeling: We will use the results from ongoing field programs to test our ability to model realistic coastal polynyas in the Bering, Okhotsk and Chukchi Seas.

The combination of process-oriented and realistic modeling will allow us to refine our dynamical ideas in the context of observed forcing and environmental factors, and thereby progress toward an ability to make accurate estimates of dense-water production and shelf-basin exchange.


ARCTIC SHELF AND BASIN PRODUCTIVITY

Glenn F. Cota
Center for Coastal Physical Oceanography, Old Dominion University, Norfolk, VA 23529
Lawrence R. Pomeroy
Department of Zoology and Institute of Ecology, University of Georgia, Athens, GA 30602

The NSF/ONR Western Arctic Shelf Basin Interactions (SBI) program has identified biological production and biogeochemical cycling as priorities for improving our ability to predict environmental change in the Arctic. Primary producers play a central role in marine food webs and biogeochemical cycles, but their response to environmental changes can only be assumed because in many regions we have little or no direct knowledge of historical productivity. Our principal goal is to determine regional patterns of primary productivity on Arctic shelves, slopes and basins. Although we will focus on the Chukchi and Beaufort Seas, our efforts will encompass most of the Arctic Ocean and its marginal seas. Our main objectives are to: 1) better understand the mechanisms responsible for regional differences in productivity, 2) determine the net trophic status of regions to evaluate the potential for shelf-basin exchange of organic materials, 3) focus hypotheses and research efforts in subsequent phases, 4) provide validation data for coupled biophysical models in all phases (e.g. J.J. Walsh and others), and 5) establish benchmarks to assess environmental change. With climatologies and simple models of physical forcing and biogenic activities we propose to constrain estimates of primary production with two different approaches: 1) a "top down" irradiance forced model, and 2) a "bottom up" water column biogeochemical model. The irradiance-based model utilizes climatologies of clouds, radiation, and ice and snow cover to define the light available for photosynthesis by phytoplankton and ice algae. The biogeochemical model utilizes oxygen and nutrient profiles to estimate seasonal primary production (total and new) and net community trophic status from late summer property distributions. Whenever possible we will compare direct photosynthetic measurements and oxygen fluxes with modeled productivity estimates.

We have already accumulated ca. 4500 oxygen profiles and 2000 nitrate profiles from Arctic shelves and basins to estimate regional patterns. More data are also being collected. Although some data are from other seasons, most profiles are from the late summer "navigable" season and represent post-bloom conditions. The data sets span most of this century and a few locations have multiple revisits within and between years, which may help assess seasonal and interannual variability. Large databases with both biogeochemical and physical observations are necessary to validate models of primary productivity, and carbon, nitrogen and silicon fluxes. This project complements current and planned research to study the Arctic Ocean and its marginal seas.



COLLABORATIVE RESEARCH: PALEOCEANOGRAPHIC RECORDS OF WESTERN ARCTIC SHELF-BASIN INTERACTIONS

Dennis Darby, Jens Bischof, and Greg Cutter, Dept. of Ocean, Earth, & Atmospheric Sciences, Old Dominion University, Norfolk, VA 23529
Anne de Vernal, GEOTOP and Claude Hillaire-Marcel, Universite du Quebec a Montreal, C.P. 8888 Succursale Centre Ville. Montreal, Quebec, Canada H3C 3P8
Gary Dwyer, Division of Earth and Ocean Sciences, Old Chemistry Building, Duke University, Durham, NC 27708
Leonid Polyak, Byrd Polar Research Center (Office Of Research), 274 Scott Hall, 1090 Carmack Road, Columbus, Oh 43210
Richard Poore and Lisa Ostermann, USGS, MS 955 National Center, 12201 Sunrise Valley Drive, MS 955, Reston, VA 20192
James McManus, Large Lakes Observatory, University of Minnesota, 109 RLB, 10 University Dr., Duluth, MN 55812

The sediment record in the western Arctic Ocean has been shown to contain valuable information on the past climatic and oceanographic changes such as variations in sea ice coverage, iceberg and sea ice rafting, nutrient and metal contents, and faunal/floral abundances. The interactions between the Chukcki Shelf with its Pacific water component and the deep adjacent basins is the focus of the Western Arctic Shelf-Basin Interactions Program (SBI). This collaborative research proposal addresses some of the critical questions raised by SBI and will meet some of its basic goals and establish critical data for Phase II of SBI. Recognizing the temporal variability of sediment proxies for productivity, different water masses, riverine influx, sources of ice-rafted detritus (IRD), different water current regimes, and sea ice extent and thickness is critical to understand the processes that cause these changes. We propose a coordinated study of the important sediment proxies in three to five piston cores currently in cold storage at the U.S.G.S. At least one of these cores is suspected to extend back to oxygen isotope stage 5 at a core depth of about 650 cm. All of these cores from the slope and Northwind Basin appear to have sufficiently high sedimentation rates to permit century to millennium scale resolution. Our focus will be on the last 50-100 kyrs with emphasis on the changes recorded during the Holocene. Detrital Fe oxide grains will be matched to previously characterized circum-arctic source areas by discriminant function analysis using electron microprobe geochemical compositions of individual grains. Similarly, coarse lithic grain assemblages will be matched to sources using the clast petrology and mineralogy. These independent source determinations will provide information on changes in IRD sources and thus details on water mass circulation and climatic conditions. Microfaunal data will provide spacial and temporal data on: 1) benthic biodiversity and abundance, 2) shelf-to-basin sediment fluxes, 3) deep and intermediate water mass distribution and circulation, and 4) sea ice distribution and general thickness. Chemical analyses of foraminifer and ostracode tests (including stable isotopes) will provide similar data on: 1) the thermal structure of the western Arctic Ocean, 2) Arctic deep and intermediate water mass distribution and circulation (especially the strength of the warm Atlantic layer), and 3) the depth and extent of the halocline. Cd in benthic foraminifers has proven to be a valuable surrogate for phosphate, and thus is a quantitative indicator of upwelling intensity. Measurements of the sediment organic carbon, nitrogen, sulfur, and carbonate carbon, along with sedimentation rate determinations by AMS radiocarbon analyses will provide information of the biogenic flux rates from the surface waters. A combination of elements accumulating in marine sediments including Ba, U, Cd, and Mo provide a powerful tool for quantifying the export of organic carbon from the surface ocean to the sea floor. These proxies are critical for determining paleoproductivity and to improve quantitative reconstructions of past conditions. The records of past global change in the Arctic Ocean, when compared to other records from the global ocean, are the only means we have to assess if the Arctic is a harbinger of global change. Records of paleo-upwelling and productivity, for example, allow us to quantitatively assess the frequency and driving mechanisms of change in this environment, and hence to better understand and predict current and future changes.

BENTHIC COMMUNITY STRUCTURE AND BIOMASS IN THE WESTERN ARCTIC: LINKAGE TO BIOLOGICAL AND PHYSICAL PROCESSES

Ken Dunton, University of Texas at Austin, Marine Science Institute, Port Arkansas, TX 78373
David Maidment, University of Texas at Austin, Austin, TX 78712
Jackie Grebmeier, Department of Ecology and Evolutionary Biology, The University of Tennessee, Knoxville, TN 37996

Spatial and temporal patterns in the flux of sinking matter are critical to the development and productivity of the benthos, particularly at high latitudes where environmental controls are extreme. The input of this energy, in the form of highly reduced organic matter, ultimately links production in the water column with the abundance and diversity of the benthos. The goal of our proposed research is to utilize the benthos as a spatial and temporal integrator of oceanographic processes that could provide a valuable indicator of potential global change impacts.
Spatial and temporal patterns in the flux of sinking matter are critical to the development and productivity of the benthos, particularly at high latitudes where environmental controls are extreme. The input of this energy, in the form of highly reduced organic matter, ultimately links production in the water column with the abundance and diversity of the benthos. The goal of our proposed research is to utilize the benthos as a spatial and temporal integrator of oceanographic processes that could provide a valuable indicator of potential global change impacts.

Within the Western Arctic Shelf-Basin Interactions (SBI) program, Phase I was designed to undertake retrospective studies of data sets in the Chukchi and Beaufort Seas that would help focus future research efforts on the impacts of global change on arctic ecosystems. There exist large and potentially invaluable historical databases from the Arctic region that have not been synthesized, including thousands of records on the biomass, density, and composition of benthic organisms from the Chukchi and Beaufort, mostly unpublished. A wide variety of information on physical and geochemical parameters, including the seasonal extent of ice cover, circulation patterns, water column characteristics and sediment parameters, are also available from both published and unpublished sources. Together, these sources of information represent a substantial collection of baseline data, most of which was collected 20-30 years ago.

The purpose of the work proposed here is to retrieve benthic biological data from NODC and other published and unpublished data sets from western and Russian sources and use Geographic Information Systems (GIS) software to examine and graphically display relationships between predominant physical forcing processes (e.g. freshwater inflows, ice cover, circulation) and ecosystem productivity. Preliminary development of coupled biological and physical models based on historical data would provide an opportunity to identify specific research needs and refine hypotheses with respect to the processes regulating biogeochemical cycles and biologicaproductivity on Arctic shelves.l


TRACER BASED EXAMINATION OF HALOCLINE AND FRESH WATER EXCHANGE IN THE WESTERN ARCTIC

Kelly K. Falkner,.College of Oceanic and Atmospheric Sciences, Oregon State University, Corvallis , OR 97311

This proposal is a contribution to Phase I (retrospective data synthesis and modeling) of the Western Arctic Shelf-Basin Interactions (SBI) program. The main goals of the SBI program are to understand quantitatively and mechanistically the major processes involved in shelf water mass modification, including biogeochemical transformations, exchange with the Arctic Ocean interior and the biological structure and function of Arctic shelf and slope ecosystems. Achievement of these goals is prerequisite to development of a predictive capability regarding the Arctic system response to and role in global change.

Four main objectives are to be addressed in this proposal which are aimed at improving the knowledge base from which to design an effective field strategy for SBI. They are concerned with the application of tracers, primarily Ba, to questions of water mass origin and transformations occurring both for the whole Arctic shelf-basin system and specifically in Beaufort and Chukchi regions. Work to date by our laboratory group suggests that Ba may be a particularly useful dye of Mackenzie River and the Bering Sea inputs, which play a dominant role in the Beaufort and Chukchi seas respectively and enhance stratification in the western Arctic.

The first objective is to add the Ba data base to an inverse box-model of Arctic shelf-basin exchange recently developed by others. This model has demonstrated through the use of temperature, salinity and del-18O fields that tracer constraints significantly reduce uncertainties in the magnitudes of the exchanges required to achieve heat, salt and mass balances consistent with known boundary flows. It is hypothesized that inclusion of the Ba data base, which is an order of magnitude larger than the del-18O data base and inherently contains information orthogonal to that tracer, would reduce errors even further and so improve the integrated estimate of the relative contribution of processes involved in shelf-basin exchange. This exercise requires characterization of all boundary flows for the system. A ship-of-opportunity transect in the Fram Strait for Ba is presently being collected as part of the European VEINS program. The proposed analyses of these samples would complete a first order characterization of advective boundary flows for the Arctic system. The non-advective flux terms are to be addressed as part of the second objective.

The second objective is to obtain a first order estimate of the vertical flux of particulate Ba under the ice cover via the analysis of existing sediment trap samples available to us via collaboration with Canadian colleagues at the Institute of Ocean Sciences, Sidney BC. The samples span the time frame from 1987 to the present and include transects of the Canadian Beaufort Shelf in the Mackenzie region, a long time series at a climate station in the deep Beaufort and a time series from the drifting SHEBA site. Additional information on currents, light transmission, particle transmissometry and hydrography complement this sample suite. Our collaborative arrangement involves provision of training in state-of-the-art analytical methodology at COAS facilities to a Canadian student and colleagues.

The third objective involves completion of the analyses of an extensive suite of samples in the Chukchi and Beaufort region (1992-1997) and examination of that data set for clues regarding modification of shelf source waters and their variability. This project will involve collaboration with several colleagues who kindly provided us with samples from their expeditions and possess a range of complementary measurements. While some findings have already been reported from these missions, they were not funded for the topics discussed here and so the data have yet to be fully explored in these respects.

The fourth objective is to assure the development of an on-board and perhaps in-situ technique for Ba analysis in a time-frame suitable for application during SBI. An on-board technique offers the improvement of being able to make informed decisions regarding sampling in the field. Continuous methodology can overcome resolution limitations inherent to bottle sampling based measurements but its development is far more challenging. ONR funds, awarded to undertake these developments, are limited and so funding is requested here to support the second year of a graduate student's related research.

Sharon Smith

University of Miami RSMAS - MBF , 4600 Rickenbacker Cswy, Miami , FL 33149-1098

This project will initiate a study of the advection of large copepods onto continental shelves from the deep Arctic basin as a vital source of carbon for the planktonic ecosystem on the shelf. Without this source of carbon, the planktonic biota would have little food supply and the benthic fauna would dominate the food web. This fundamental process of transferring carbon from basin to upper waters of the shelf has not been studied in the Arctic ecosystem. The process is very important due to the possible overwintering of the copepods in the deep basin where they can serve as an annual source of food for zooplankton and fish when advected to the shelf during the short
Arctic summer. The investigator will use retrospective analysis of data collected in the Chukchi and Beaufort Seas to develop a biological model of the advection of copepods to test hypotheses about the migration of plankton as well as the effects of ocean circulation on the process. The model will allow testing of global change impacts on the availability of this important food source on the shelf. The results of this project will provide input for planning a large Phase 2 field program of the Shelf Basin Interactions project in 2002 in the same geographic area.

LIGHT AND LIFE IN THE WESTERN ARCTIC OCEAN: A CONTRIBUTION TO THE SHELF-BASIN-INTERACTIONS (SBI) PROGRAM

^{Knut Stamnes and Bingquan Chen}
Department of Physics and Engineering Physics, Stevens Institute of Technology, Castle Point on Hudson, Hoboken, New Jersey 07030

The polar regions are the places on Earth where potential climate changes are likely to be first observed. Expected changes due to stratospheric ozone depletion are increased levels of ultraviolet-B (UV-B) radiation, large enough to have harmful effects on aquatic and terrestrial ecosystems. Potential changes in cloudiness due to climate changes will also strongly affect both UV and photosynthetically active radiation (PAR). In spite of the significant changes recently observed in the ozone layer over the Arctic, little has been done to measure and model the corresponding changes in the underwater UV and PAR
radiation environment and their impact on marine arctic ecosystems. On this background, one of the objectives of the proposed research is to develop a computationally-efficient radiative transfer model specifically tailored for the tightly coupled atmosphere-sea ice-ocean environment, test it against spectral irradiance measurements, integrate it with an existing phytoplankton model designed to interpret field measurements, and perform sensitivity studies of the impact of changes in atmospheric and oceanic parameters on primary production, taxonomic structure, and biological diversity in arctic waters. Another
objective is to measure and theoretically predict underwater spectral irradiance and its variation with depth in arctic waters as a function of changes in atmospheric ozone concentrations, meteorological conditions, ice/snow cover, and sea water type. A third objective is to use the measurements to establish a data base that can be used in future studies (including the phase 2 and phase 3 in the SBI program as well as other related studies) and monitoring of the arctic environment by satellite remote sensing. The last objective is to carry out remote-sensing study to derive cloud and surface parameters (albedo) that can be used to characterize the radiation budget in the Western Arctic, modify and improve previous approaches for retrieving the chlorophyll pigments, and establish data sets of cloud and surface parameters (albedo) as well as chlorophyll pigments for high latitudes and coastal waters in the Western Arctic for the SBI program.

CIRCULATION AND THERMOHALINE STRUCTURE ALONG THE CHUKCHI-BEAUFORT CONTINENTAL SLOPE.

Thomas Weingartner

Institute of Marine Science, University of Alaska Fairbanks, Fairbanks, AK 99775

This program will investigate the circulation and thermohaline structure of the Chukchi-Beaufort continental slope during SCICEX99. This project seeks to better understand the poorly sampled circumpolar boundary currents of the Arctic Ocean. These flows are important in the distribution and exchange of mass, heat, and materials around the basin and between the shelves and the interior ocean. The measurements, collected from sail-mounted CTDs and submarine launched expendable CTDs (SSXCTD), will determine the correlation length scale of the along slope thermohaline fields, the magnitude and structure of the alongshore baroclinic pressure gradient, and alongslope variations in the cross-slope baroclinic pressure gradient. The data should shed light on the scales of cross-slope exchanges and forcing mechanisms for the eastward-flowing boundary current. The temperature and salinity measurements will complement ADCP and chemical data sets being collected by other investigators. In aggregate the data sets will help characterize the mesoscale circulation and establish the mixing history of the regional waters. This proposal complements a mooring program (supported by the MMS) that will provide concurrent time series of velocity, temperature, and salinity at several locations along the Alaskan Beaufort slope and within the sampling grid of the SCICEX-99 expedition.

CONFIGURATION OF AN ECOSYSTEM MODEL FOR THE CHUKCHI SEA USING DATA FROM 1994-1996.

P. A. Wheeler and Y. H. Spitz
Ocean Administration Bldg 104, College of Ocean & Atmospheric Sciences, Oregon State University, Corvallis, OR 97331-5503

Past ecosystem models for the Chukchi Sea have lacked critical verification data. We propose to use a data assimilation scheme, results from the 1994 AOS Arctic Ocean Section, and additional chemical and biomass data from two 1996 cruises to adapt a recent improvement of an Atlantic Time Series ecosystem model to the Chukchi Sea ecosystem. Initial development of the ecosystem model will focus on the lower trophic level pelagic system. Subsequent versions will be expanded to include specific parameters for benthic process and remineralization and for the seasonal activity of the sea ice biological communities.

The model will be used to evaluate the sources and sinks of organic carbon and nitrogen in the Chukchi Sea, and the export of inorganic nutrients, particulate and dissolved organic material from the shelf sea into the Canadian Basin. By understanding the factors that regulate biological processes on the shelf, we will be able to predict the effects of changes in physical parameters (including climate and ice cover) on the magnitude and fate of shelf production and the exchange of nutrients between the shelf and the basin.

Major gaps or uncertainties of model parameters will be identified at each stage of development. Ship of opportunity cruises will be used in 1999-2001 to expand data coverage, to test predictions of the model, and to lead to model refinement. At each stage in the proposed work we will prepare and update the list of minimum core measurements that will be needed in future field studies to address the key questions about the influence of global change on the amounts and fates of primary production in the Chukchi Sea. As platforms for sampling and appropriate data become available we will extend the proposed ecosystem model to the Beaufort Sea.


A SYNTHESIS OF ARCTIC OCEAN TIME SERIES, WITH APPLICATION TO SHELF-BASIN INTERACTIONS

Rebecca Woodgate & Knut Aagaard
University of Washington, Seattle, Washington 98105

The aim of this project is to analyze and synthesize a multi-year collection of moored time series (mainly of velocity, temperature, and salinity) from various regions of the Arctic Ocean and its shelves and adjacent seas. Our goals are to understand the physics of high latitude shelf-basin interactions and to provide an observationally based indication of the variability of the shelf-basin system, with an emphasis on the western Arctic and its role in the pan-Arctic system. This work gives an observational background for the SBI program.

The SBI region is influenced by both local shelf processes and the larger scale arctic circulation. Relevant to the former, the on-going analysis of data from the Bering Strait and Chukchi Sea is concentrated on the transports of water and ice towards the Arctic Ocean. Strong correlations between the ice motion and the wind and the currents suggest that it may be possible to use these latter two records as proxies for the northward ice export. From a pan-Arctic perspective, the fastest oceanic connection between the SBI region and the rest of the Arctic is most likely via the Arctic Ocean boundary current, which is directed cyclonically around the Arctic Basin. Time series from near the junction of the Lomonosov ridge with the Eurasian continent reveal the local properties of this current. It is strongly baratropic and shows no significant seasonal variation. The flow is weak (a few cm/s) in the mean, although the records show the passage of highly energetic (up to 40 cm/s) eddies, some of which are probably formed in convectin polynyas on the shelves. The boundary current, which has a mean transport of 5+_ 2 Sv, is split almost in half by the Lomonosov Ridge, with 3+- 1 SV crossing the ridge into the Canadian Basin. Important in the context of SBI, shelf-induced water mass transformations are transported long distances by the boundary current. For example, changes in the outflow from the Barents Sea can be traced over the Lomonosov Ridge (Woodgate et al.SBI poster) and into the Beaufort Sea. (McLaughlin et al. SBI poster).

Thus, to understand the SBI region, we need to assess both the impact of the boundary current and the local shelf processes. Further analysis will address these and other issued, including the flow and variability in the Beaufort Sea.

Weingartner, Tom weingart@ims.alaska.edu (907) 474-7993 fax (907) 474-7204 Institute of Marine Science University of Alaska Fairbanks Fairbanks, AK 99775-7220
Wheeler, Patricia pwheeler@oce.orst.edu (541) 737-0558 fax (541) 737-2064 Oregon State University Ocean Administration Bldg. 104 College of Ocean & Atmospheric Sciences Corvallis, OR 97331-5503
Whiteheard, John jwhitehead@whoi.edu (508) 289-2793 fax (508) 289-2181 Physical Oceanography Department Woods Hole Oceanographic Institution, M#21
Whitledge, Terry terry@ims.uaf.edu (907) 474-7229 fax (907) 474-7204 School of Fisheries and Ocean Sciences P>O> Box 757220 University of Alaska Fairbanks Fairbanks, AK 99775-7220
Woodgate, Rebecca woodgate@apl.washington.edu (206) 543-8942 fax (206) 616-3142 Polar Science Center – APL University of Washington 1013 NE 40th Street Seattle, WA 98105-6698