Buoys Track Cook Inlet Currents

Submitted by Doug Schneider
Phone: 907-474-7449
05/13/03

COOK INLET, Alaska-- Navigating Alaska’s Cook Inlet might seem a fairly easy task. After all, the inlet is more than 20 miles wide in places. But looks are deceiving. Lying in wait to make life difficult and sometimes deadly for fishermen, cargo ship captains and offshore oil and gas platform operators is a mix of swift currents, whirlpools, and sandbars that seem to come and go. And that’s just in the summer. During winter, add to the mix hazards like pack ice that at best slows ship traffic and at worst closes the inlet to vessels entirely.

And then there are notorious tides that periodically raise and lower the inlet’s water level by nearly 40 feet. That kind of fluctuation makes Cook Inlet second only to Nova Scotia’s Bay of Fundy.

Into this chaotic marine world scientists from the University of Alaska Fairbanks School of Fisheries and Ocean Sciences and the Woods Hole Oceanographic Institution recently placed three specially equipped research buoys. The buoys will drift throughout the summer with the inlet’s currents and tides as part of a three-year study to understand how these powerful forces affect sea ice and sediments in the region. The three buoys were released northeast of Kalgin Island, within the inlet’s narrows, in early April with the help of Cook Inlet Spill Prevention and Response, Inc.

Mark Johnson, oceanographer at the UAF Institute of Marine Science, said the buoys and images recorded by orbiting satellites will help him and his colleagues create accurate computer models of the inlet to better understand these interactions. The study is funded by the federal Minerals Management Service through the Coastal Marine Institute at the University of Alaska Fairbanks School of Fisheries and Ocean Sciences.

"With 2-D and 3-D ice-ocean computer models, we will be able to simulate tidal rips, wind-driven and thermohaline circulation in Cook Inlet," said Johnson. "The bouys drifting with currents in the inlet will provide the real-world data we need to verify how well these models work."

Over the study’s three years, Johnson and his colleagues will deploy about 45 beachball-size buoys into the inlet and track them as they drift. The researchers will recover the buoys each fall, or after they run aground or drift into the Gulf of Alaska. Throughout the winter, scientists will monitor currents using satellites that track ice movement in the inlet.

UAF researcher Steve Okkonen said computer models are widely used tools that in this case will help scientists better understand how Cook Inlet currents distribute sediment and impact ice. Such a model is needed for Cook Inlet as ship traffic, as well as oil and gas exploration, increase in the waterway. Okkonen said better models that predict where the huge amounts of sediment that flow from rivers into the inlet each summer will end up also is important to the placement of undersea power cables, telecommunications and oil and gas pipelines.

Mark Johnson recently returned from a year-long sabbatical as The Office of Naval Research Arctic Chair in Polar Marine Science at the U.S Naval Postgraduate School in Monteray, California.

Mark Johnson profile www.sfos.uaf.edu/directory/faculty/johnson

Online Research Abstract: Water and ice dynamics in Cook Inlet www.sfos.uaf.edu/cmi/meetings/03/annualreview/abstracts.htm

Contact: Dr. Mark Johnson, Professor, University of Alaska Fairbanks, School of Fisheries and Ocean Sciences, Institute of Marine Science, 907 474-6933, johnson@ims.uaf.edu