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Western Arctic Shelf-Basin Interactions (SBI) Project
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SBI PI Meeting Over 70 participants attended the one-day SBI PI meeting. Short update presentations were made by SBI Phase I PIs/co-PIs during the morning and early afternoon sessions; some of these talks had poster presentations at the OAII PI meeting held earlier in the week. The following statements briefly outline the general discussion points of these talks (further information can be found in the PI project abstracts posted on the SBI web page: <http://www.utk-biogw.bio.utk.edu/SBI.nsf >). A. SBI PI Presentations Aagaard-There has been a freshening through the Bering Strait region, with a decadal change of about 1.5 per mil. The annual salinity cycle has been reduced by about one-half, coincident with a reduction in flow through Bering Strait. Currently two moorings were placed in Bering Strait in summer 1999, with the first-year turn-around planned for summer 2000. Chapman and Gawarkiewicz-The path of dense water flow over and off the shelf is highly dependent on bottom topography. There is a need to understand the impact of ice production on eddy formation and transport down Barrow Canyon. Cota and Pomeroy- Property distribution were presented for low trophic water column properties in a pan-Arctic sense and preliminary results from the computer synthesis of data currently in progress were presented. Darby et al.-The preliminary results from the paleoceanography retrospective study were presented. The average sedimentation rate across the Arctic varies from 8-40 cm/1000 yr, with the Late Glacial maximum rates a magnitude greater (80-400 cm/1000 yr). Dunton et al.-The presentation made outlined the goals and preliminary results of the GIS program undertaken to consolidate benthic data in the Bering, Chukchi and Beaufort Seas. In addition, this project will map other lower trophic and environmental data to produce overlay maps for the SBI study area that will be available to the scientific community via a web page, and form the basis for initially modeling efforts. Harvey et al.-The PIs are using a suite of molecular organic markers in sediments as productivity signals which will assist in determining preliminary budgets for marine and terrestrial carbon reservoirs on the shelf, slope and basin. The measurements include alkenones, bulk C,/N/S values and isotopes, and markers such as lipids and macromolecular compounds. Kadko- Radium-228 to radium-226 ratios are being used to investigate cross-shelf transport of particulate materials. This project includes both retrospective data analysis and ship-of-opportunity sampling. Maslowski et al.- This talk outlined a global circulation model in progress, including physical oceanographic and tracer parameters. Preliminary results can be found on the web page: <http://web.nps.navy.mil/~braccio/maslowski/arctic.html> and <www.oc.nps.navy.mil>. In addition, these modeling efforts include work on the PIPS3 model. Plueddeman- This research is testing the possible mechanisms to supply bottom trapped boundary currents by generated eddies to help explain cross-shelf transport. Dense water formed on the shelf can influence the slope current as well as detach to form eddies that can transport water and energy offshore. An important question is how much of the Pacific signal goes into the basins and out Fram Strait vs. how much transits through the Canadian Archipelago. Smith- This presentation indicated the available data sets on zooplankton production in the SBI region and how these organisms can act as tracers of cross-shelf and slope exchange of Pacific and basin waters. Stamnes- Data was presented on ultraviolet radiation input in the Arctic, specifically on changes in UV penetration with changes in atmospheric ozone concentrations, meterological conditions, snow cover, and water clarity and optical properties. This group is developing a model for a coupled atmosphere-ocean-ice for integration in a 1-D regional marine ecosystem model. Spitz and Wheeler- This presentation described the pelagic ecosystem model currently under development, its components, and the data sets being used. Moorehead- This project is a laboratory approach to understanding eddy formation and transport mechanisms to move shelf waters offshore. B. Discussions of SBI Phase II Implementation Plan The mid-afternoon discussion session included the topic of mesoscale and small scales studies within the SBI program and how to address this topic in the Phase II Implementation Plan. This draft plan needs to provide guidance to the scientific community. The standard measurements for the program need to be made available to all the PIs and interested scientific community. The process-type studies would be undertaken by individual/group Pis in Phase II. The primary vessels for the SBI study would be the new USCGC Healy and the UNOLS vessel RV Alpha Helix, along with international vessels. Sue Moore provided a brief outline of marine mammal studies in the Western Arctic and Bernie Zak provided a brief description of the DOE/ARM program was made which has the largest meterological instrumentation in the Arctic and this network could be a valuable asset to the SBI program. 1. SBI Study Area The flow regimes through Bering Strait and into the western Chukchi Sea are important. The densest water has been seen to flow out Barrow Canyon, and different processes influence Pacific water as it transits the shelves and enters to Arctic Ocean interior.[ It was noted that this region is the "blubber factory" for marine mammal mothers and babies.]. The following points briefly outline some compare/contrast the two widest continental shelves in the Arctic Basin: the Bering/Chukchi Shel and the Barents Shelf:
_ key process: this transport of water has impact on larger ocean systems _ one pivotal topic: transformation of large throughflow shelves _ change over time of physiography of Arctic shelves and associated influence
_ extreme property gradients _ Arctic shelves: need feedback for Arctic stratification structures, transformation of global water properties and biogeochemical products
_ Need to study global Arctic heterogeneity _ Terrestrial erosion _ Importance polynyas along coast 2. The question came up as to whether we need to know the seasonal cycle of the SBI area. The consensus was YES. The following points were raised:
_ Different time scales of variability _ Shelf keeps working all year long – at what level? _ Need some cold season rate for processes _ Data indicate early season processes may be more seasonally driven than originally thought _ Essential time series/time scale research 3. Do we need a multi-year study? The answer is YES. The following points were raised:
_ Needed to overcome interannual variability _ Results multi-year SBI study input in development/refinement of long term observatories pan-Arctic _ LTO decadal time scale _ Identify parameter range necessary/determinable _ Focus on location 4. Are there common denominators for multi-year study? The following points were raised:
_ one unique feature: Bering Strait inflow and variability features _ coastal polynyas _ what happens at shelf break related to exchange processes, as influenced by Bering Sea transport and regional polynyas/events _ consider surface/subsurface flows and transportation for biogeochemical signals _ alterations w/global change of transport and processes of freshwater flows _ change riverine: zonal general atmospheric circulation ( SEARCH, RAISE) _ how change in sea ice influences biogeochemical cycles in Beaufort Sea Biota 1. zooplankton could be used as tracers of water masses from Pacific into Canada Basin to compare the advective transfer of the production of C vs in situ production of C: Chukchi Sea Beaufort Sea ---------------à upwelling
Pacific flora (Barrow) and Atlantic flora (Prudhoe) as a reflect circulation patterns 2. isotopic signatures could also be used as well as historical data as water mass and productivity tracers 6. A first-order question related to the red study box on the SBI map (link to top map SBI home page): 1. signal determination thru the Bering Strait – how many days before reaching shelf break 2. transformation processes: Chukchi Beaufort extreme biogeochemical modifications vs how freshwater sources as Pacific water transits shelf modifications on shelf what are the pros/cons for extending the study areas? 3. Objectives:
_ How much $ _ What hand level collaboration 7. The following GAPS/NEEDS were identified for further discussion and evaluation for the implementation plan:
_ Seabeam (USCGC) _ SBI specific requests _ HEALY in winter vs ice cap? _ Limitation only 30 days _ Availability of other ships in addition to HEALY for broad-scale studies _ Balance between possible broad-scale vc experimental studies _ Underway CTDs _ Lagrangian perspective in biology; bring in new technologies _ Moorings (yo-yo problem) _ What's the meaning of past data/retrospectives? Any holes?
_ need perspective on past _ International Arctic Bouy program _ Swath seabeam mapping (HEALY – USCG trials) _ Issue level instrumentation development before Phase II The meeting ended with the tasking to incorporate comments from SBI meeting as well as those made during the OAII meeting to enhance the draft SBI Phase II implementation plan. Another iteration of the plan would be available before the planned March 2000 SBI PI meeting. |