Jule Gregory Charney (1917–1981)

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Jule Gregory Charney was born in San Francisco, California, on January 1, 1917, the son of Ely Charney and Stella Littman. Both parents were Yiddish-speaking Russian Jews, and both worked in the garment industry. The family moved to the Los Angeles area in 1922. All of Charney’s earned degrees were from the University of California at Los Angeles (UCLA): an A.B. in mathematics in 1938, an M.A. in mathematics in 1940, and a Ph.D. in meteorology in 1946. From 1942 to 1946, Charney was an instructor in physics and meteorology at UCLA. His dissertation, titled “Dynamics of long waves in a baroclinic westerly current,” comprised the entire October 1947 issue of the Journal of Meteorology. This paper was influential in two important ways: (1) it emphasized the influence of “long waves” in the upper atmosphere on the behavior of the entire atmosphere rather than the more traditional emphasis on the polar front and (2) it provided a simplified way of analyzing perturbations along these waves that proved both physically insightful and mathematically rigorous.

After graduation, Charney served for a year as a research associate at the University of Chicago. During the academic year 1947–1948 he held a National Research Council postgraduate fellowship at the University of Oslo, Norway. During this year he developed a set of equations for calculating the large-scale motions of planetary-scale waves known as the “quasi-geostrophic approximation.” Charney’s technique consisted of replacing the horizontal wind by the geostrophic wind in the term representing the vorticity but not in the term representing the divergence. The result was a manageable set of filtered equations governing large-scale atmospheric and oceanic flows.

From 1948 to 1956, Charney was a member of the Institute for Advanced Study in Princeton, New Jersey. His supervisor, the noted mathematician John von Neumann, was in charge of a project to develop an electronic computer. Charney served as director of the theoretical meteorology. His group constructed a successful mathematical model of the atmosphere and demonstrated that numerical weather prediction was both feasible (using the ENIAC computer, which took 24 hours to generate a forecast) and practicable (using von Neumann’s stored-program computer to generate a forecast in 5 minutes). In 1954, Charney helped establish a numerical weather prediction unit within the U.S. Weather Bureau.

Charney was professor of meteorology at the Massachusetts Institute of Technology (MIT) from 1956 to 1981 and was Alfred P. Sloan Professor there from 1966. His research focused on the dynamics of atmospheres and oceans. From 1963 to 1966 he was chair of the National Research Council’s Panel on International Meteorological Cooperation and from 1968 to 1971 he was chair of the U.S. Committee for the Global Atmospheric Research Program (GARP), a decade-long international experiment to measure the global circulation of the atmosphere, to model its behavior, and to improve predictions of its future state. Charney was instrumental in articulating the global goals and vision of GARP and consistently argued that scientists needed to view the atmosphere as a single, global system.

Charney was elected to Phi Beta Kappa in 1937. He was a Fellow of the American Academy of Arts and Sciences, the American Geophysical Union, and the American Meteorological Society. He was a member of the U.S. National Academy of Sciences and a foreign member of the Norwegian and Royal Swedish Academies of Science. Among his many awards were the Meisinger Award (1949) and the Rossby Medal (1964) of the American Meteorological Society, the Losey Award of the Institute of Aeronautical Sciences (1957), the Symons Medal of the Royal Meteorological Society (1961), the Hodgkins Medal of the Smithsonian Institution (1968), and the International Meteorological Organization prize (1971). He was much in demand as a visiting professor and guest lecturer. The University of Chicago awarded him an honorary D.Sc. in 1970.

Charney was married to Elinor Kesting Frye in 1946. Elinor had a son who took the Charney name; the couple had two other children. Following a battle with cancer, Charney died in Boston on June 16, 1981.

In 1990, the American Meteorological Society published a memorial volume containing reprints of Charney’s most important papers and articles by scientists who knew him. Jule Charney’s personal papers are located in the MIT archives.

 

—James Rodger Fleming

Colby College
Waterville, Maine

Jacob Bjerknes (1897–1975)

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Jacob Aall Bonnevie Bjerknes was born in Stockholm, Sweden, in 1897. He continued a legacy of hydrodynamic application theory that began with his physics professor grandfather Carl and was extended by Jacob’s father, the theoretical physicist Vilhelm Bjerknes. From 1914 to 1916, Bjerknes attended the University of Kristiania (Oslo), where he became interested in his father’s work relating hydrodynamic theory to atmospheric motion and weather prediction. Jacob followed his father and his group of young Norwegian meteorologists to the University of Leipzig, where their research focused on the formation of heavy precipitation along ordered cloud boundaries then called “squall lines.” Through surface map analysis, Jacob discovered that these boundaries coincided with the convergence of wind fields, making the latter a potential detector and predictor of weather patterns.

Vilhelm Bjerknes returned to Norway in 1918 and founded a geophysical institute at the University of Bergen, where he organized an analysis and forecasting branch which would evolve into a weather bureau by 1919. During this period, Jacob’s research resulted in the identification of two boundary lines of convergence (one leading, one following) as an integral part of atmospheric wave development (cyclogenesis) which could progress to the formation of a low-pressure center and the southward transfer of polar air. In his classic paper “On the structure of moving cyclones” in 1919, Bjerknes introduced the concept of the “extratropical cyclone,” which became a foundation for the long-range weather forecasting envisioned by his father. The group at Bergen, now including the Swedish meteorologists Carl Gustav Rossby and Tor Bergeron, used balloon data to investigate the “squall line” boundary in three dimensions and realized that it was a thermal discontinuity of hemispheric proportions. Defining it as the “polar front” (borrowed from World War I terminology), they named the two active convergence lines of the cyclone model the “warm front” and the “cold front.” As pointed out in a key paper by Jacob and Halvor Solberg in 1922 (“The life cycle of cyclones and the polar front theory of atmospheric circulation”), the dynamics of the polar front, integrated with the cyclone model, provided the major mechanism for north-south heat transport in the atmosphere. For this and other research, Jacob was awarded the Ph.D. from the University of Kristiania in 1924.

In 1926, Jacob served as a support meteorologist for Roald Amundsen’s polar dirigible flight. In 1928 he married Hedvig Borthen. In 1931, he left his position as head of the weather service at Bergen to become professor of meteorology at the geophysical institute his father had founded. By 1933 he discovered yet another aspect of the cyclone phenomenon, the upper atmospheric wave. His preliminary formulation of the use of pressure tendency as a surface indication of cyclone development appeared in 1937.

Jacob lectured at the Massachusetts Institute of Technology during the 1933–1934 school year and emigrated to the United States in 1940 where he headed a government-sponsored meteorology annex, for weather forecasting, to the department of physics at the University of California, Los Angeles (UCLA). That same year of 1940 saw the invasion of Norway by Germany and Bjerknes’ receipt of the Symons Medal from the Royal Meteorological Society. At UCLA, Bjerknes and fellow Norwegian Jorgen Holmboe further developed the pressure tendency and the extratropical cyclone theories.

The science of meteorology entered the computer and space ages during the 1950s. Bjerknes, then head of the department of meteorology at UCLA, was an early advocate of using photography from rockets to image atmospheric weather patterns, and he would later help usher in the use of satellites for the same purpose. Bjerknes’ cyclone model was a key element in the Princeton atmospheric program used to obtain the first accurate computer-aided weather forecast in 1952. Bjerknes’ later research focused on the energy exchange of the atmosphere and oceans and, specifically, the El Niño effect.

To his friends, Bjerknes was just “Jack.” With his students, he was always conscientious in sharing his gift for simplifying the complexity of atmospheric motion. The American Geophysical Union honored Bjerknes’ pathbreaking work in meteorology in 1945 with the William Bowie Medal, its highest award, recognizing fundamental contributions to geophysics and the AGU principle of unselfish cooperation in research. Additional honors included the American Meteorological Society’s Rossby Medal (1960) and the National Medal of Science (1966). Bjerknes died in 1975.

—William J. McPeak

Lake Forest, California