Peter Niiler Profile

Scripps Institution of
Oceanography/UC San Diego

Peter Niiler of the Scripps Institution of Oceanography did not set out to become an authority on ocean circulation. He says it was something he just happened to be good at. Peter credits much of his success to a rigorous education grounded in fundamentals and precision. One never got credit in college for an answer if the second decimal place was not correct.

Peter’s approach to studying the ocean circulation continues to be grounded in fundamentals and precision. One cannot develop a useful model of what drives global ocean circulation, he says, without understanding what is happening at the scale of a cubic centimeter. Yet his approach also encompasses a much broader vision of the ocean. For the past forty years, Peter has helped reshape how scientists study the ocean. Whereas oceanographers once focused on naming and defining currents, they now stress the processes driving these currents and measuring them accurately. And whereas oceanographers once limited their perspectives to small regions of the ocean, they now understand the importance of viewing the ocean on a global scale. It was his generation of scientists, Peter says, that helped bring about these changes.

Peter was born in Estonia in 1937. At age twelve, his parents brought him to western Pennsylvania. He studied engineering in college, and then applied mathematics and fluid mechanics in graduate school. Then at the urging of Henry Stommel, a pioneer in the study of ocean circulation, Peter joined Nova University in Fort Lauderdale, Fla., in 1966 where he studied the Florida Current and Gulf Stream in a small laboratory on a houseboat. He went on to teach oceanography at Oregon State University for eight years before joining Scripps as a professor in 1982.

Peter and a few of his colleagues have long understood the linkage between ocean circulation and the world’s climate. But he said that it wasn’t until the 1980s that these ideas gained more urgency among a broader group of earth scientists, prodded in large part by emerging evidence that the buildup of carbon dioxide in the atmosphere was altering the world’s climate. Yet unraveling the circulation remains daunting. Not only do the oceans contain a maze of often shifting current systems, they are filled with turbulence that can be viewed on a scale of just a cubic centimeter to the thousands of swirling eddies a few hundred kilometers wide.

Before the 1980s, most scientists were turning to data on sea surface temperature and salinity to gain insights about circulation. But Peter wanted to get back to basics: deploy instruments that directly measure the flow.

Oceanographers have been releasing drifters to track currents since the three-year British Challenger Expedition in the early 1870s. But Peter discovered that the available instruments were not up to the task. Not only were they expensive, costing up to $12,000 each, they did not follow the water that well. Wind and waves pushed them off course, and the equations engineers had devised to correct for these errors were far off.

So Peter and his colleagues set out to redesign the buoys. They increased the drogue size relative to the surface float to minimize the effects of wind and waves. They made the buoys tougher, increasing their longevity from 150 to 450 days. And they lowered the cost of each buoy to under $2,000.

The buoys relay their positions by transmitting radio signals at a precise frequency. A satellite receives the signals as it approaches and then passes the buoy. Computers then calculate the buoy’s position based on frequency changes due to the Doppler effect. Peter and his colleagues have since added sensors that measure water temperature, salinity, atmospheric pressure, and wind; data that has proven invaluable for calibrating satellites that collect the same information. Today Peter and his colleagues work closely with manufacturers to solve problems and update the designs while keeping costs down.