Walter Munk
Walter Heinrich Munk 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, 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 at the University of California in La Jolla. 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.
Early life and education
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, 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 in Pasadena. While at Caltech, he took a summer job in 1939 at the Scripps Institution of Oceanography in La Jolla, California. Munk earned a B.S. in applied physics in 1939 and an M.S. in geophysics 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.
Wartime activities
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:
Oceanographic measurements during atomic weapons tests in the Pacific
In 1946, the United States tested two fission nuclear weapons 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 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
After receiving his doctorate in 1947, Munk was hired by Scripps as an assistant professor of geophysics. He became a full professor there in 1954, but his appointment was at the Institute of Geophysics at the University of California, Los Angeles. In 1955, Munk took a sabbatical at Cambridge, England. His experience at Cambridge led to the idea of starting a new IGP branch at Scripps.At the time of Munk's return to Scripps, it was still under the administration of UCLA, as it had been since 1938. It became part of the University of California, San Diego when that campus was founded in 1958. Revelle, its director at the time, was a primary advocate for establishing the La Jolla campus. At this time Munk was considering offers for new positions at the Massachusetts Institute of Technology and Harvard University, but Revelle encouraged Munk to remain in La Jolla. Munk's founding of IGP at La Jolla was concurrent with the creation of the UCSD campus.
The IGPP laboratory was built between 1959 and 1963 with funding from the University of California, the U.S. Air Force Office of Scientific Research, the National Science Foundation, and private foundations. The redwood building was designed by architect Lloyd Ruocco, in close consultation with Judith and Walter Munk. The IGPP buildings have become the center of the Scripps campus. Among the early faculty appointments were Carl Eckart, George Backus, Freeman Gilbert and John Miles. The eminent geophysicist Sir Edward "Teddy" Bullard was a regular visitor to IGPP. In 1971 an endowment of $600,000 was established by Cecil Green to support visiting scholars, now known as Green Scholars. Munk served as director of IGPP/LJ from 1962 to 1982.
In the late 1980s, plans for an expansion of IGPP were developed by Judith and Walter Munk, and Sharyn and John Orcutt, in consultation with a local architect, Fred Liebhardt. The Revelle Laboratory was completed in 1993. At this time the original IGPP building was renamed the Walter and Judith Munk Laboratory for Geophysics. In 1994 the Scripps branch of IGPP was renamed the Cecil H. and Ida M. Green Institute of Geophysics and Planetary Physics.
Research
Munk's career in oceanography and geophysics touched on disparate and innovative topics. A pattern of Munk's work was that he would initiate a completely new topic; ask challenging, fundamental questions about the subject and its larger meaning; and then, having created an entirely new sub-field of science, move on to another new topic. As Carl Wunsch, one of Munk's frequent collaborators, commented:Wind-driven gyres
In 1948, Munk took a year's sabbatical to visit Sverdrup in Oslo, Norway on his first Guggenheim Fellowship. He worked on the problem of wind-driven ocean circulation, obtaining the first comprehensive solution for currents based on observed wind patterns. This included two types of friction: horizontal friction between water masses moving at different velocities or between water and the edges of the oceanic basin, and friction from a vertical velocity gradient in the top layer of the ocean.The model predicted the five main ocean gyres, with rapid, narrow currents in the west flowing towards the poles and broader, slower currents in the east flowing away from the poles. Munk coined the term "ocean gyres," a term now widely used. The currents predicted for the western boundaries were about half of the accepted values at the time, but those only considered the most intense flow and neglected a large return flow. Later estimates agreed well with Munk's predictions.