On October 16, 1969, MIT professor Henry Melson Stommel wrote to a worldwide group of his peers, the Scientific Committee on Oceanic Research, to propose an experiment of unprecedented scope: an international initiative to measure the general circulation of the Atlantic Ocean. The plan involved a 100,000-square-mile patch of rough water, six research vessels, and on-call air support. The Mid-Ocean Dynamics Experiment (MODE) was hatched.
Well into the 20th century, conventional theory held that ocean currents were slow, deep, and relatively constant. Stommel, who arrived at the Woods Hole Oceanographic Institution (WHOI) in 1944, suspected otherwise. Unusual among his colleagues for having no doctorate (he held a BS in astronomy from Yale but cut short his graduate studies to help the war effort at WHOI), he nevertheless published widely on deep-sea fluid dynamics. He found evidence that the ocean was as chaotic as the atmosphere, buffeted by swirling eddies and fluctuating pressure zones. The seas, it seemed, experienced volatile “weather” too.
The challenge would be proving it. No one had ever seen such an eddy before, let alone measured one in open water. Stommel had pressed for a large-scale study, writing in 1958 that such a project would yield “a contribution to physical oceanography that will make even Scripps [Institute of Oceanography] and the Russians take notice.”
A few years earlier, British oceanographer John C. Swallow had designed a buoy to emit pings that could be tracked with underwater microphones while it drifted across the water surface. When he released a batch in the Sargasso Sea near Bermuda in 1959, he expected their movements to be fairly predictable; instead, he watched his buoys scatter in every direction. Swallow’s findings gave Stommel hope that he could rally support for his cause.
Stommel (who joined MIT’s faculty in 1963) worked steadily over the next decade to build the case for a grand experiment that would take advantage of Swallow’s buoys and ongoing advances in vertical pressure gauges, current meters, and temperature sensors to create a richly detailed map of a deep ocean storm. When his 1969 proposal found favor within the oceanographic community, he didn’t waste any time. He procured resources from 13 institutions—including computational models from Scripps, graduate students from Harvard, and research ships from his old colleagues at WHOI. Researchers from 21 nations, including Sweden, West Germany, and the Soviet Union, signed on to observe.
The experiment focused on 28°N, 69°W, roughly 500 miles southwest of Bermuda, where the Gulf Stream, the North Atlantic Current, and the North Equatorial Current collide to create some of the roughest seas in the world. Although previous oceanographic experiments had analyzed data only after the fact, Stommel had findings sent back daily so that the researchers could monitor progress and react quickly to unexpected problems.
Since shipboard radios had limited range, his team set up a relay center at the Bermuda Biological Station to gather data from the ships and cable a daily digest to WHOI headquarters in Massachusetts and other interested institutions via an undersea telephone party line leased from the government of Bermuda.
Finally, in March 1973, six research vessels, two aircraft, and dozens of scientists converged on Bermuda. Over the next four months, the ships monitored designated sections of the ocean spanning an area about the size of Colorado, deploying a colorful variety of floats, sensors, and buoys to take multiple readings of the same sections. Planes dropped pressure gauges, shuttled repair equipment, and hunted for wayward buoys. Little-used Navy microphones, originally built to calculate impact points of test missiles fired over the Atlantic, were repurposed to track Swallow’s buoys (though Stommel asked a journalist to remove that detail from a contemporary article, citing “certain Navy sensibilities”).
The operation was considered a success, disrupted only when the research vessel Chain hit a log in April and had to return to Norfolk, Virginia, for repairs. The project officially concluded in July, having detected multiple eddies, the elusive vortexes that dictate the flow of the seas. The findings, compiled in a 274-page atlas that researchers continue to mine today, offered the first glimpse of the ocean storms that Stommel had predicted.
Forty years after it was carried out, MODE remains the standard for international ocean research. For Stommel, it was a validation of intrepid field science. As he would later conclude: “To be able to give undivided attention to unraveling some puzzle of nature is a privilege beyond compare.”
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