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The Pacific Gateway to the Arctic

Russian American Long-term Census of the Arctic

By Kathleen Crane (CPO, NOAA), Rebecca Woodgate (University of Washington, UW), Tom Weingartner (University of Alaska, Fairbanks, UAF), Terry Whitledge (UAF), and Ron Lindsay (UW)

The Bering Strait, a narrow and shallow strait at the northern end of the Pacific, is the only ocean gateway between the Pacific and the Arctic. Although the flow through the strait is small in volume, due to its remarkable properties (high heat and freshwater content, low density, high nutrients) it has a strong influence on the surrounding ocean and seas, the North Atlantic overturning circulation and possibly the world’s climate. The Bering Strait throughflow is an integrated measure of Bering Sea change. The comparatively warm, fresh throughflow contributes ~ 1/3rd of the freshwater input and possibly ~ 1/5th of the oceanic heat input to the Arctic, and provides the most nutrient-rich waters entering the Arctic Ocean.

Illustration of the currents in the Bering Strait

Figure 1. Illustration of the currents through the Bering Strait.

However, due to a lack of data and monitoring, scientist's understanding of the properties that affect variability in the Bering Strait is still rudimentary. Although recognized as a key ocean gateway by national and international global observing initiatives, there was no long-term observing strategy for the Bering Strait until the development of the RUSALCA program (Russian-American Long-term Census of the Arctic). Building on US-Russian collaborations established in 2004 and a 2007 NOAA - NSF collaboration to build the critical observing chain of moorings in this Pacific - Arctic Gateway, the RUSALCA program undertook the first ever deployment of instrumentation in both the Russian and U.S. waters of the Bering Strait in August-September of 2007 onboard the Russian Naval hydrographic vessel "SEVER".

The objectives of the program are: (1)To measure the velocities and water properties of the Bering Strait throughflow; (2)To understand the physical processes influencing the properties of the Bering Strait throughflow, with special focus on mechanisms driving change, and impacts on the Arctic Ocean; (3) To quantify (or at least bound) oceanic fluxes of volume, freshwater, heat, nutrients, and chlorophyll biomass through the strait; and (4) To design an optimum monitoring system for oceanic fluxes through the Bering Strait.

Figure 2. RUSALCA Stations in the Bering Strait. 2007 mooring locations are red, Conductivity, temperature and depth (CTD) stations in black. Depth is in meters.

Additionally, the RUSALCA Bering Strait moorings will provide an observational platform for other Bering Strait measurements; an annually- updated status of Bering Strait fluxes and potential Arctic impacts for the science community and the general public; and public dissemination of results and the importance of global oceanography to US schools and the general public, including via a Polar Science Weekend at the Pacific Science Center (Seattle’s major science museum).

By quantifying and understanding oceanic fluxes at this key Pacific-Arctic ocean gateway, this work contributes directly to NOAA’s mission of documenting the climate system and detecting change.

Contact: Kathleen Crane, Climate Program Office Program Manager for the Arctic Research Program, (301) 427-2471, kathy.crane@noaa.gov

http://www.arctic.noaa.gov/climate/
http://www.climate.noaa.gov

The Climate Program Office (CPO), created in October 2005, incorporates the Office of Global Programs, the Arctic Research Office, and the Climate Observations and Services Program and, coordinates climate activities across all NOAA. The new CPO focuses on developing a broader user community for climate products and services, provides NOAA a focal point for climate activities within NOAA, leads NOAA climate education and outreach activities, and coordinates international climate activities. NOAA's Climate goal is to: "Understand and describe climate variability and change to enhance society's ability to plan and respond".

10/8/07

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