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COI Funded Project: Quantifying cross-shelf exchange in the Hudson Shelf Valley. Is the Hudson Shelf Valley a nutrient pump?

Project Funded: 2006

What are the primary questions you are trying to address with this research?
The Hudson Shelf Valley, located south of Long Island, is the only canyon that cuts across the entire continental shelf of the Middle Atlantic Bight. Consequently, the Hudson Shelf Valley provides a potentially important conduit for exchange across the shelf. This study will estimate the cross-shelf transport and associated upwelling in the Hudson Shelf Valley, investigate the physics of this flow to determine what forces the flow up the canyon, and determine the relationship between onshore flow in the valley and phytoplankton bloom events.

What is the significance of this research for others working in this field of inquiry and for the broader scientific community?
We hypothesize that the onshore flow within the valley may be an important mechanism for upwelling of nutrient-rich water near the coast that fuels phytoplankton blooms in the New York Bight.

What is the significance of this research for society?
Canyons or valleys may be important conduits for transporting material across the continental shelf. This may include, for example, onshore and upward transport of nutrients to fuel phytoplankton blooms as hypothesized here, or the offshore transport of sediments or pollutants.

When and where will this investigation be conducted?
This is analysis of existing data acquired as part of a joint USGS/WHOI study of sediment transport within Hudson Shelf Valley.

What are the key tools or instruments needed to conduct this research?
Existing data was collected using acoustic current meters, pressure sensors, and temperature-conductivity sensors.

What are the greatest challenges - physical or intellectual - to conducting this investigation?
Obtaining the observations that are accurate enough to determine the basic physics of canyon flows is extremely challenging. For example, the pressure gradients that drive flows up or down the canyon are the result of very small sea surface slopes of only a few centimeters (1 inch) over 100s of kilometers (100 miles).

Is this research part of a larger project or program?

Biographical information:
Steven J. Lentz is presently a Senior Scientist in the Department of Physical Oceanography at Woods Hole Oceanographic Institution. His research focuses on coastal physical oceanography. He earned B.A.s in mathematics and applied mechanics and engineering science from University of California, San Diego in 1977 and a Ph.D. in oceanography from Scripps Institution of Oceanography in 1984. He subsequently went to Woods Hole Oceanographic Institution as a Visiting Investigator in 1985, was subsequently hired to a tenure-track position in 1987. His r esearch interests include the dynamics of river plumes entering the ocean, wind-driven circulation, and processes contributing to cross-shelf exchange.

Originally published: October 1, 2006