Walter Heinrich Munk (October 19, 1917 – February 8, 2019) was an American physical oceanographer. He was one of the first scientists to bring statistical methods to the analysis of oceanographic data. Munk worked on a wide range of topics, including surface waves, geophysical implications of variations in the Earth's rotation, tides, internal waves, deep-ocean drilling into the sea floor, acoustical measurements of ocean properties, sea level rise, and climate change. His work won awards including the National Medal of Science, the Kyoto Prize, and induction to the French Legion of Honour.
Munk's career began before the outbreak of World War II and ended nearly 80 years later with his death in 2019. The war interrupted his doctoral studies at the Scripps Institution of Oceanography (Scripps), and led to his participation in U.S. military research efforts. Munk and his doctoral advisor Harald Sverdrup developed methods for forecasting wave conditions which were used in support of beach landings in all theaters of the war. He was involved with oceanographic programs during the atomic bomb tests in Bikini Atoll.
Beginning in 1975, Munk and Carl Wunsch developed ocean acoustic tomography to exploit the ease with which sound travels in the ocean and use acoustical signals for measurement of broad-scale temperature and current. In a 1991 experiment, Munk and his collaborators investigated the ability of underwater sound to propagate from the Southern Indian Ocean across all ocean basins, with the aim of measuring global ocean temperature. The experiment was criticized by environmental groups, who expected that the loud acoustic signals would adversely affect marine life. Munk continued to develop and advocate for acoustical measurements of the ocean throughout his career.
For most of his career, he was a professor of geophysics at Scripps. Additionally, Munk and his wife Judy were active in developing the Scripps campus and integrating it with the new University of California, San Diego. Munk's career included being a member of the JASON think tank, and holding the Secretary of the Navy/Chief of Naval Operations Oceanography Chair.
In 1917, Munk was born to a Jewish family in Vienna, Austria-Hungary. His father, Dr. Hans Munk, and his mother, Rega Brunner, divorced when he was ten years old. His maternal grandfather was Lucian Brunner (1850–1914), a prominent banker and Austrian politician. His stepfather, Dr. Rudolf Engelsberg, was head of the salt mine monopoly of the Austrian government and a member of the Austrian governments of Chancellor Engelbert Dollfuss and Chancellor Kurt Schuschnigg.
In 1932, Munk was performing poorly in school because he was spending too much time skiing, so his family sent him from Austria to a boys' preparatory school in upper New York state. His family envisioned a career for him in finance with a New York bank connected to the family business. He worked at the family's banking firm for three years and studied at Columbia University.
Munk hated banking. In 1937, he left the firm to attend the California Institute of Technology (Caltech) in Pasadena. While at Caltech, he took a summer job in 1939 at the Scripps Institution of Oceanography (Scripps) in La Jolla, California. Munk earned a B.S. in applied physics in 1939 and an M.S. in geophysics (under Beno Gutenberg) in 1940 at Caltech. The master's degree work was based on oceanographic data collected in the Gulf of California by the Norwegian oceanographer Harald Sverdrup, then director of Scripps.
In 1939, Munk asked Sverdrup to take him on as a doctoral student. Sverdrup agreed, although Munk recalled him saying "I can't think of a single job that's going to become available in the next ten years in oceanography". Munk's studies were interrupted by the outbreak of World War II. He completed his doctoral degree in oceanography at Scripps under the University of California, Los Angeles in 1947. He wrote it in three weeks and it is the "shortest Scripps dissertation on record." He later realized that its principal conclusion is wrong.
In 1940, Munk enlisted the U.S. Army. This was unusual for a student at Scripps: all the others joined the U.S. Naval Reserve. After serving 18 months in Field Artillery and the Ski Troops, he was discharged at the request of Sverdrup and Roger Revelle so he could undertake defense-related research at Scripps. In December 1941, a week before the Japanese Attack on Pearl Harbor, he joined several of his colleagues from Scripps at the U.S. Navy Radio and Sound Laboratory. For six years they developed methods related to antisubmarine and amphibious warfare. This research involved marine acoustics, and eventually led to his work on ocean acoustic tomography.
Predicting surf conditions for Allied landings
In 1943, Munk and Sverdrup began looking for a way to predict the heights of ocean surface waves. The Allies were preparing for a landing in North Africa, where two out of every three days the waves are above six feet. Practice beach landings in the Carolinas were suspended when waves reached this height because they were dangerous to people and landing craft. Munk and Sverdrup found an empirical law that related wave height and period to the speed and duration of the wind and the distance over which it blows. The Allies applied this method in the Pacific theater of war and the Normandy invasion on D-Day.
Officials at the time estimated that many lives were saved by these predictions. Munk commented in 2009:
The Normandy landing is famous because weather conditions were very poor and you may not realize it was postponed by General Eisenhower for 24 hours because of the prevailing wave conditions. And then he did decide, in spite of the fact that conditions were not favorable, it would be better to go in than lose the surprise element, which would have been lost if they waited for the next tidal cycle [in] two weeks.
Oceanographic measurements during atomic weapons tests in the Pacific
In 1946, the United States tested two fission nuclear weapons (20 kilotons) at Bikini Atoll in the equatorial Pacific in Operation Crossroads. Munk helped to determine the currents, diffusion, and water exchanges affecting the radiation contamination from the second test, code-named Baker. Six years later he returned to the equatorial Pacific for the 1952 test of the first fusion nuclear weapon (10 megatons) at Eniwetok Atoll, code-named Ivy Mike. Roger Revelle, John Isaacs, and Munk had initiated a program for monitoring for the possibility of a large tsunami generated from the test.
Later association with the military
Munk continued to have a close association with the military in later decades. He was one of the first academics to be funded by the Office of Naval Research, and had his last grant from them when he was 97. In 1968, he became a member of JASON, a panel of scientists who advise the Pentagon, and he continued in that role until the end of his life. He held a Secretary of the Navy/Chief of Naval Operations Oceanography Chair from 1985 until his death in 2019.
Institute of Geophysics and Planetary Physics