large team of researchers will invade the California coast near San Luis Obispo
this month to launch an intense study of the Pacific Ocean’s inner shelf – a
little-studied region between the surf zone and the mid-Continental Shelf.
many as 100 scientists from 13 institutions and agencies will use a wide array
of tools to monitor this stretch of ocean that runs roughly from shoulder-deep
water out to 50 meters deep.
goal is to understand the complex currents, how water moves between the shore
and deeper ocean, the origin of rapid changes in temperature, and how ocean
energy is dissipated near the shore. These processes, in turn, can drive
sediment transport and primary biological production.
going to give this inner shelf region a complete physical,” said Jack Barth, an
Oregon State University oceanographer and a principal investigator on the
study, one of the largest of its kind, is funded by an $11 million grant from
the Office of Naval Research. The researchers will use satellites, airplane
surveillance, camera-equipped drones, ground-based radar, five ships, anchored
moorings and seafloor-based platforms with instrument arrays, oceanic
profilers, and even floating “drifters” to record physical data in the ocean
along the inner shelf.
stretch of Pacific Ocean just south of San Luis Obispo was chosen because it
has both a simple, straight stretch of coastline and prominent points jutting
out into the ocean, which adds complexity to the currents and mixing, the
researchers say. Surprisingly, this inner shelf area has not been studied
comprehensively because parts of it are too shallow for larger ships, yet it
extends beyond where surf zone researchers typically work.
massive study was conceived five years ago and has been in the planning and
development stages for two years, allowing scientists and technicians to
develop and perfect the instrumentation they will deploy in September and early
October. It is reminiscent of two other major efforts in the United States –
the Coastal Ocean Dynamics Experiment, or CODE, along the northern California
coast in 1981-82, and a comprehensive study of the surf zone in Duck, North
Carolina, in the 1980s and 1990s.
observational data that will emerge from this concentrated study will challenge
and inform oceanic models for decades,” Barth said. “We are still using data
from the CODE project 35 years ago.”
Lerczak, an Oregon State scientist specializing in the physics of the ocean and
atmosphere, said one reason the U.S. Navy is interested in the study is to
improve its ability in assessing currents, navigation, and optics in regions
without actually going there. The researchers will use satellites, ground-based
radar and airplanes to analyze the waters from above, Lerczak said, and compare
those observations with actual measurements taken in the ocean.
is a very complex region that not only is influenced by wind, currents and
tides, but also by large ‘internal’ waves that propagate along the Continental
Shelf because of the tides and stratified water,” Lerczak said. “These waves
bring cold water up into the surf zone and back, usually twice a day. They not
only have a significant physical impact, but a biological one as well because
they bring to shore cold, upwelled water that is nutrient-rich.”
Moum, an Oregon State University oceanographer, received a separate grant from
the Office of Naval Research to develop a series of turbulence sensors (or
“mixing meters”) designed to measure where energy from currents and waves goes
in the inner shelf region. In one of the largest efforts of its kind, Moum and
his colleagues will deploy dozens of these sensors on the seafloor, on moorings
and on instrument platforms towed behind research vessels to better understand
how the Pacific Ocean “works.”
basically studying fluid mechanics on a huge scale,” Moum said. “We’ll be
taking a host of measurements from scales of hundreds of meters – instabilities
created by currents and winds – down to scales of millimeters and centimeters,
where mixing actually takes place. We’ve only recently learned that there is a
daytime peak for turbulence, but we’re not sure why. We’re just beginning to
findings from the study will inform not only scientists, but recreational
boaters, fishermen, beach-goers and the U.S. Navy.
water between the surf zone and the mid-shelf is where rip currents take place,
and where crabbers and fishermen and other boaters spend a lot of time,” Barth
said. “It is also critical from an ecological standpoint, where larval
organisms propagate offshore, and then return to the surf zone. It is where
plankton bloom and fuel the marine food web.
we know little about the physics of how this inner shelf works.”
institutions and agencies involved in the study include Naval Postgraduate
School, Scripps Institution of Oceanography, University of Washington, Georgia
Tech University, Naval Research Laboratory/Stennis Space Center, University of
Miami, Spoondrift, University of California Los Angeles, Delft University of
Technology, Florida State University, University of Michigan and University of