Research Highlight: Scripps and the Science behind the D-Day Landings

Note: Walter Munk and his wife, Mary Coakley Munk, will be in Normandy in early June to attend events commemorating the 70^th anniversary of D-Day.

Guests visiting Walter Munk’s home may lose track of their visit’s main purpose, as they are captured not only by the beautiful panoramic ocean view, visible from the backyard, but also the art and memorabilia that fills the home.

Asian statuettes sit near Munk’s computer monitor, a photograph of a younger Walter is visible among the oceanography books and news clippings sprawled across his work desk, and a painting of him and his late wife Judy hangs high on a wall. In the distance, the campus of Scripps Institution of Oceanography at UC San Diego is clearly visible.

Founded in 1903, Scripps specializes in ocean, earth, and atmospheric science research, education, and public service. Munk, a Scripps geophysicist and Secretary of the Navy/Chief of Naval Operations Oceanography Chair, explains that his first exposure to Scripps came following his junior year at Caltech. He was dating a girl whose grandparents lived in La Jolla, where she planned to spend the summer. At that time La Jolla consisted of summer cottages and Scripps was affectionately known as the “Bug House” at the north end of the (La Jolla) village.

“I needed a job in order to date her and Scripps was the only option!” says Munk. “My love affair with her ended the following year, but my love affair with Scripps has lasted 75 years to date.”

Attracted to the sun’s warmth, Munk beckons his guests outside and begins to recount the events that led up to his wave prediction method being adopted by the U.S. Navy during World War II.

His account begins first at the Pentagon, where he worked as a meteorologist, and later in North Carolina, where he observed practice landings in preparation for the first Allied initiative in Oran in northwest Africa. When waves exceeded five feet, Munk remembers, the LCVPs (Landing Craft, Vehicle, Personnel, or “Higgins boat”) would broach, waves would break into the LCVPs, and people would get hurt. They would call it a day and resume the exercises when the waves were lower.

Munk returned to the Pentagon and reviewed literature about winter waves in northwest Africa. He learned that they generally exceeded six feet and therefore he believed the plan was a catastrophe about to happen. 

“I remember asking my commanding officer about this and he said ‘They have thought about it,’ and told me to get back to my own work,” Munk said.

Munk enlisted in the Army in 1939 and was later excused from military service to work on methods to enhance amphibious warfare for the Navy.

“I was 25 with no education and no background, but I just couldn’t let go of (the wave prediction issue),” Munk said. “So I called my old colleague Dr. Sverdrup at Scripps, told him what I thought, and asked him to fly out and meet me in D.C., where I was working at the time.”

Munk lights up when speaking about Dr. Harald Ulrik Sverdrup, an oceanographer, meteorologist, director of Scripps from 1936 to 1948, and Munk’s mentor.

“After months of trying to figure out how to predict waves, we were satisfied that it could be done,” said Munk. “Harald had a major reputation in the world and they listened to him.”

The Sverdrup-Munk wave prediction method aimed to help Allied forces predict waves in order to land their troops safely on shore during amphibious invasions and to avoid failed attacks.

First tested in 1942, their basic swell forecasting scheme was paired with another similar wave prediction method created by British Royal Navy Commander Claude Suthons, who provided the British assault force with graphs that showed wave height, wave duration, and wave decay rates with wind speed. These methods were paired with aerodynamic and hydrodynamic concepts, which led to the successful invasion of French North Africa during Operation Torch, an American-British invasion during World War II.

Following the success of the landings in North Africa, Munk and Sverdrup were authorized to open a school for meteorological officers from both the Army and Navy.

“We spent a year training 10-12 officers a month, and had 10 classes, so there were over 100 officers,” said Munk. “The method we worked on in class is the method generally used now.”

The first component of the three-part method, Munk says, is to compute the waves in the storm area, or “the sea.” The second is to estimate what happens when waves travel from the storm area to the distant landing beaches, or “the swell.” And finally, the method analyzes what happens when the waves come into shallow water, “the surf.”

"When the method is applied properly, it is successful,” said Munk. “Later on, two of the officers who had been in the class here at Scripps participated in the wave predictions for D-Day. I myself did not have the chance to participate in the D-Day wave predictions.”

Officers Charles Bates and John Crowell both had backgrounds in science. Bates graduated from DePaul University with a degree in geophysics, and Crowell from UCLA with a degree in geology. Bates and Crowell would use the Sverdrup-Munk method along with the Suthons forecasting method to prepare for D-Day.

Operation Overlord, led by General Dwight D. Eisenhower, was the code name for the invasion of Normandy by Allied forces in German-occupied France. It was the largest amphibious assault ever attempted, utilizing 7,000 vessels and 160,000 troops.

To properly plan for Normandy, the officers used weather and swell data, aerial photographs, and intelligence gathered by spending time with amphibious operations units to learn first-hand the capabilities of the crafts being used.

Munk learned of the events that took place during Operation Overlord from declassified information and from speaking with Bates and Crowell.

“On June 5, 1944, when the operation was supposed to take place, there were very high winds, and Eisenhower made the decision to wait 24 hours,” Munk explains. “However, 24 hours later, the Americans predicted there would be a break in the storm and that conditions would be difficult, but not impossible.”

Eisenhower decided to proceed with the operation. In hindsight, Munk learned later that the Nazis’ wave prediction was more accurate.

“They thought it would be too dangerous for Allied forces to attempt a landing,” said Munk. “The German’s assumption, and the chance Eisenhower took, helped preserve the element of surprise that the Allies needed for a successful landing on the beach,” Munk says, smiling again.

Eventually, Munk’s work with the Navy and the United States would extend far beyond Operation Overlord.

“After the war, I tried to focus on other things besides wave predictions, but the waves kept calling to me,” Munk says.

Munk would form a deep bond with Roger Revelle, the oceanographer and former director of Scripps who led the institution during the “golden age of oceanography” and was the driving force in the founding of UC San Diego in 1960.

“Walter Munk’s contributions to D-Day are a significant part of World War II history, as well as a proud reminder of the legacy of science built here in La Jolla over the past 111 years,” said UC San Diego Chancellor Pradeep K. Khosla. “Today UC San Diego continues on this path with new insights in the frontiers of understanding and protecting the planet.”

In 1946, Munk helped with testing nuclear weapons in the Pacific Ocean. In 1968 he became a member of JASON, an independent group of scientists that advises the American government on issues related to science and technology. Among his many awards, Munk was awarded the Maurice Ewing Medal, sponsored by the American Geophysical Union and the Navy, in 1976.

“With his early critical successes in the science of wave forecasting, Walter Munk continued to push and expand ocean and earth research in the decades that followed and throughout his career,” said Margaret Leinen, director of Scripps Oceanography. “Walter has earned every bit of his worldwide distinction in oceanography and geophysics.”

Munk has worked with the Office of Naval Research (ONR) for 50 years analyzing long-range acoustics, acoustic propagation, and wave studies. ONR appreciated Munk’s work so much that in 1993 they founded the Walter Munk Award, which is given annually to a scientist or researcher in the oceanography field. The first recipient was Walter Munk himself.

“ONR takes great pleasure in being able to date our association to Professor Munk and his many oceanographic contributions to the beginnings of our command,” said Dr. Frank Herr, head of the Office of Naval Research’s Ocean Battlespace Sensing Department. “The wave forecasting technique, updated, is still an important contribution today.”

At 96, Munk shows no sign of letting up, saying that he will continue to work as long as he can to help the Navy achieve its goals at sea.

“To my knowledge, we hadn’t used wave predictions for amphibious operations before World War II, but I’m glad to see how far we have come since,” says Munk.

— Mass Communication Specialist 3rd Class James Vazquez, U.S. Navy Public Affairs Support Element West, and Mario C. Aguilera, Scripps Institution of Oceanography Communications

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