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Physical Oceanography, Biology, and Changing Climate
Glacier Bay National
Park – a Living Laboratory
Glacier Bay National Park (GBNP), located in southeastern Alaska, is a region of remarkable extremes. Topography ranges from sea-level to the 15,000 ft peaks of the Fairweather range. Bathymetry ranges from shallow estuarine sills created by glaciers to channels 500 m deep. There is no shortage of rainfall either, with coastal areas receiving in excess of 12 ft per year.
GBNP is also a region of diversity and abundance. At the nexus of terrestrial, freshwater,
and marine ecosystems, the park is home to moose, brown and black bears, whales, orcas, dolphins,
and countless species of seabirds, fishes, and invertebrates. This concentration and diversity
of species is one of the primary reasons that GBNP received national park status in 1980.
Finally, GBNP is a region of rapid change. In the past 200 years, glaciers have retreated more than 50 miles, releasing enough water to raise global sea levels by one centimeter. This rapid retreat has left behind remarkable spatial gradients in land cover, from mature forests in the southern regions to seedling alders establishing footholds in newly exposed granite slabs in the northern regions. Rapid changes are also being observed in species abundance. For example, populations of the Kittlitz’s Murrelet were documented to drop by nearly 80% during the past two decades in Glacier Bay.
Penn State researchers Dr. David Hill and Suzanne Ciavola have been working with biologists
from GBNP and the United States Geological Suvey to help establish and understand the connections
between physical and biological processes in park waters. The PSU researchers have been conducting
modeling studies of the tidal circulations in the bay and of the freshwater runoff into the
bay. Their work has yielded valuable contributions to the understanding of the freshwater budget
of the bay. Additionally, it has begun to help explain the spatial variations in species abundance
observed in the bay.
During the summer of 2007, the PSU researchers traveled to GBNP to conduct field measurements of streamflow in a number of watersheds draining into the bay. They experimental challenges they faced included equipment failures due to the relentless rain and sharing the streams with plentiful grizzly bears. Nevertheless, the measurements they made were found to successfully validate their modeling approaches. With this validated model, they have therefore produced a reliable tool that can be used to study future scenarios (increased / decreased precipitation and glacial retreat) and their impacts on the oceanography and biology of the bay. Planned future work by Dr. Hill and his students includes refining the numerical modeling approach and extending the analysis to include all of coastal southeastern Alaska.
For more information please visit the Glacier
Bay Tidal Modeling webpage.
Inquiries may be
directed to Dr. Hill at dfh4@psu.edu.
Contributed by David Hill, associate professor of Civil and Environmental Engineering