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Oceanography of the Beaufort Gyre: state and problems

This talk explores the state and variability of the Beaufort Gyre (BG) system and its regulating mechanisms in relation to oceanographic conditions. It discusses the role of the Barrow Cabled Observatory (BCO) in contributing to our understanding and prediction of the BG system. The talk covers atmospheric, sea ice, and ocean mechanisms and interactions in the context of the entire BG system.

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Oceanography of the Beaufort Gyre: state and problems

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  1. Oceanographic conditions of the Beaufort Gyre (BG) are regulated by the BG system (atmosphere, sea ice, and ocean) mechanisms and interactions and will be discussed in the context of the entire Beaufort Gyre system variability. • The major goal of this talk is to show how a long-term observational program specifically designed for the Barrow Cabled Observatory (BCO) will contribute to our understanding and prediction of state and variability of the Beaufort Gyre (BG) system, its regulating mechanisms, and impact on Arctic climate. Oceanography of the Beaufort Gyre: state and problems A. Proshutinsky, Woods Hole Oceanographic Institution Science and Education Opportunities for an Arctic Cabled Seafloor Observatory An NSF-Supported Community Meeting, Barrow, Alaska 7 – 8 February, 2005

  2. Beaufort Gyre region:

  3. BG in the Arctic climate system Aagaard and Carmack, 1994. BG

  4. Arctic Ocean: vertical stratification

  5. Kara Sea Laptev Sea Siberia 1 – Beaufort Gyre 2 – Transpolar Drift 3 – West Greenland current Barents Sea 2 3 Alaska 1 Greenland Barrow and Barrow Canyon Baffin Bay Toporkov, 1970.

  6. Coupling Diagram of the Beaufort Gyre System: Each component of the system stores and exchanges mass and energy differently during different climate regimes. Quantifying and describing the state and variability of these components and their coupling is essential to understand the state and fate of present day Arctic climate. Atmosphere Sea Ice Ocean Mixed Layer Pacific Halocline Atlantic Layer Deep Waters

  7. SOURCES OF INFORMATION: • Environmental Working Group (EWG) Atlas of the Arctic Ocean, 1997,1998 (water temperature and salinity for 1950s, 1960s, 1970s, 1980s) • 1990-present hydrographic surveys in the Beaufort Sea (submarines, icebreakers, buoys, airborne expeditions, drifting stations) • International Arctic Buoy Program (IABP): (sea level pressure, 2-m air temperature, ice drift vectors for 1979-present) • NCAR/NCEP reanalysis project (6-hourly SLP and SAT, 1948 - present) • Satellite based sea ice concentration, drift, surface temperature and other products (1978-present) • Atlases and reference books

  8. Characteristics of the Beaufort Gyre Climate System • Atmospheric system: • Atmospheric system of the BG is regulated by the Arctic Oscillation processes. The origin of these processes is debatable and is beyond our discussion here. In normal oscillating arctic climate conditions the atmospheric part of the BG is responsible for: • Forcing dynamics of anticyclonic and cyclonic circulation regimes (dynamics of AO). • Establishing positive anomalies of air temperature during high AO and negative anomalies during low AO. • Producing positive anomalies of precipitation during high AO and negative during low AO. • Variability of other atmospheric parameters (cloudiness, solar radiation, humidity, wind speed) that change from regime to regime accordingly.

  9. ATMOSPHERE and ICE DRIFT A. Winter SLP and wind B. Summer SLP and wind Over the Beaufort Gyre, large-scale atmospheric circulation changes from season to season and alternates between cyclonic (summer) and anticyclonic circulation (winter conditions). High atmospheric pressure prevails over the Beaufort Gyre in winter and low pressure dominates in summer C. Winter buoy drift D. Summer buoy drift

  10. Seasonal variability of SLP: Solid – Anticyclonic circulation regime Dotted – Cyclonic circulation regime

  11. Seasonal variability of surface winds: Solid – Anticyclonic circulation regime Dotted – Cyclonic circulation regime

  12. ATMOSPHERE and ICE DRIFT A. Winter SLP and wind B. Summer SLP and wind Figure shows that the sea ice drifts anticyclonically in both winter and summer. This is because sea ice is driven by winds and ocean currents and in the annual ice drift, the ocean currents dominate wind-driven circulation. C. Winter buoy drift D. Summer buoy drift

  13. Hydrographic station locations (blue dots) in the 1950s and 1960s

  14. Hydrographic station locations (blue dots) in the 1970s and 1980s

  15. WATER TEMPERATURE: 5 meters 1950s 1960s 1970s 1980s Source: EWG, 1997,1998

  16. WATER TEMPERATURE: 250M 1950s 1960s 1970s 1980s Source: EWG, 1997,1998

  17. WATER TEMPERATURE: 500M 1950s 1960s Atlantic water with temperatures higher than 0 C occupies water layer from 300-400 to ~1,000-1,500m in the Canadian Basin 1970s 1980s Source: EWG Atlas, 1997,1998.

  18. WATER SALINITY: 5 M 1950s 1960s Arctic surface waters occupy 30-50 meter layer with water temperatures at freezing point and relatively low salinities 1970s 1980s

  19. WATER SALINITY: 150 M

  20. Alaska Chukchi Sea Salinity distribution in the upper 200-meter layer East-Siberian Sea Beaufort Sea Beaufort Gyre Laptev Sea Kara Sea Greenland Barents Sea

  21. Top: Left: water salinity (S) at 10 m Right: Salinity section Bottom: Left:water salinity (S) at 100 m Right:Dynamic topography Data source: EWG Atlas, 1997, 1998

  22. Beaufort Gyre mechanism of fresh water accumulation and release Ice and water convergence, Fresh water accumulation due to Ekman pumping and sea ice accumulation due to ridging and cooling Beaufort Gyre Downwelling in the center and upwelling along continental slope

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