Catching waves in Chico

Chicoans flock to Chico State’s scenic Big Chico Creek Ecological Reserve (BCCER) for many reasons: to experience its diverse flora and fauna, to catch a glimpse of a black bear, to bird watch, or to hike the wild trails.

One visitor, though, is there to listen to the ocean.

That visitor is Kris Walker, PhD, project scientist at the University of California, San Diego’s Institute of Geophysics and Planetary Physics. With funding from the National Oceanic and Atmospheric Administration (NOAA), Walker partnered with Chico State to install four fiberoptic sensors in October 2010, in four locations at the 3,950-acre preserve located along Big Chico Creek above Upper Bidwell Park. The highly sensitive devices pick up frequencies of waves crashing into each other, from the middle of the Pacific, hundreds of miles away.

“Yes, it’s very bizarre,” BCCER Director Jeff Mott said of the study of the ocean from an inland location such as Chico. But being a hundred miles from the coast has no effect on the quality of the data, Walker said.

“When two waves collide, they create basically a song coming from the ocean. And you can hear that song really, really far away—thousands of miles away, sometimes,” Walker explained. Well, we can’t actually hear it. The ocean’s low frequencies that travel such long distances, said Walker, are called infrasound, or frequencies of sound below that which the human ear can detect. Walker’s highly sensitive instruments can hear those frequencies; Chico’s inland location doesn’t matter.

In fact, said Walker, “the latitude is [what’s] important.” His project has five locations gathering data, at different latitudes in the Western United States—in Washington, western Nevada, two in Southern California, and Chico. When all five register a sound, and point in the direction from which the sound emanated, he can pinpoint the location of the sound by triangulation.

Think back to basic geometry: You have five points along the base line, each pointing to the same location. Draw lines from the point toward the source of the sound, and the lines from all five locations will eventually intersect. That spot of intersection is the source of the sound.

Preliminary results of the year-plus of data collection show some interesting findings.

“We did confirm that there is a seasonal pattern with the sound,” said Walker. “We only seem to detect this particular sound during the late fall through early spring. And then, from the late spring through the early fall, we don’t hear these particular sounds. We explain this because of the winds in the atmosphere.” High atmospheric winds run eastward until the summer, when the wind is reversed, and consequently, Walker explained, “we hear things that are happening in the Atlantic Ocean in the summertime.”

Yes, you read that right: Walker’s fiberoptic sensors in Chico are picking up summertime sounds of the Atlantic Ocean, approximately 3,000 miles away.

Because it’s so far away, triangulation doesn’t work as well, and consequently, Atlantic Ocean data are less than useful to the BCCER study. But the data Walker has managed to collect about the Pacific may help such sound sensors become a regular tool in the NOAA toolkit in forecasting ocean conditions along the West Coast. Low-frequency sound monitoring like this, said Walker, can be used “to improve NOAA forecasts for wave height and advisory for boaters.”

The data collected from the BCCER sensors are transmitted immediately to a computer at the site, which sends the information to UCSD for collection. In the future, NOAA could receive data from such sensors instantly, and compare it to data already collected via satellite images, ocean buoys and other forecasting technology.

“You can use [atmospheric sound data] to validate the model of the waves in the ocean… and then you can make your forecasts much more accurate,” Walker explained.

The Chico site seems to be perfect. Walker found the area “particularly quiet,” meaning there are fewer competing low-frequency noises like airplanes or factories to interfere with data collection.

Each of the BCCER’s four sensors is a “100-foot long, 1-inch silicone tube wrapped with two fiberoptic cables,” which is then wrapped with insulation. They are protected from the reserve’s black bear population with wire cages. “The bears destroy anything that’s out there that’s manmade. You put a solar panel out there, and they bite it,” said Mott. So far, the caging has appeared to keep critters out. But, nonetheless, one of the four sensors is failing.

“The site in Chico needs repairs in a couple places, and we need some money for maintenance of that site,” said Walker. The problem isn’t a bear bite, but a “hardware or software malfunction,” he said. The five-year project’s funding from NOAA is at the whims of Congress, which approves the project’s funds as a “line item” in the larger federal budget, Walker said.

“Because of the budgetary situation, we haven’t been able to get renewed, and we’re kind of stuck,” he said. They have not received approval for two years, and Walker is not hopeful. Mott and Walker are collaborating to determine how to get additional funding to repair the Chico site in order to continue collecting good-quality data. Walker does not feel that the project has garnered enough data at this point, and it needs all four Chico sensors up and running.

With just three sensors operating, “the data quality is not quite good enough to use the site in order to do the research,” Walker said. Additionally, while sensors are collecting data, “in order to analyze the data, we need funding,” said Walker.

Mott is eager to continue the collaboration; he and Walker are working to find state-funded programs such as those through the university that may have a “chunk of change,” as Walker put it, to finish up the project.

“The purpose of the reserve is to protect the natural resources, but it’s also to promote research and education,” Mott said. “We have more than 20 research projects from CSU, Chico. But it’s also available to other universities. This project fits our mission perfectly.”