Harald Ulrik Sverdrup (1888–1957)

Harald Ulrik Sverdrup was born in Norway in November 1888. His geophysical career began with V. F. K. Bjerknes in Oslo in 1911, then in Leipzig from 1913 to 1917. During that period he published more than 20 papers on atmospheric and oceanic physics, including his Oslo doctoral thesis on the North Atlantic trade winds. As scientific director of Roald Amundsen’s polar expedition on Maud (1918-1925), Sverdrup worked extensively on meteorology, magnetics, atmospheric electricity, physical oceanography, and tidal dynamics on the Siberian shelf, and even on the anthropology of Chukchi natives. After his return, he was appointed in 1926 to the chair of meteorology vacated by Bjerknes in Bergen, and in 1931 he was appointed research professor in the Christian Michelsen Institute to work on the Maud results. At the Carnegie Institution of Washington in 1930, he began to analyze new hydrographic information on the Pacific, suggesting that its deep waters formed in the Indian Ocean sector of the Southern Ocean. He was a member of the unsuccessful Wilkins-Ellsworth North Polar Expedition in the submarine Nautilus in 1931. Always interested in boundary layer processes, Sverdrup joined H. W. Ahlmann in a 2-month expedition to the snow fields of Spitsbergen in 1934.

Upon the recommendation of Björn Helland-Hanson, Sverdrup was appointed director of the Scripps Institution of Oceanography (SIO) in 1936, ostensibly for 3 years. World War II and his sense of responsibility for the expanding SIO kept him there for 12 years. Under Sverdrup, SIO was transformed into a modern oceanographic institution, initially concentrating on study of the California Current and the Gulf of California. During this time he directed work at sea, wrote large parts of The Oceans; collaborated with Walter Munk on sea, surf, and swell forecasting for Allied landings in North Africa, Europe, and the Pacific; and coordinated the processing of oceanographic data from the Pacific. In 1947 his paper “Wind-driven currents in a baroclinic ocean” showed the link between meridional currents and the curl of the wind stress, initiating the large-scale modeling of ocean circulation elaborated soon after by Walter Munk and Henry Stommel. Inspired during his SIO years to unite oceanic physics and biology, Sverdrup quantified the concept of “critical depth” (formulated earlier by the Norwegian H. H. Gran and the American G. A. Riley) in 1953, explaining the onset of the spring phytoplankton bloom in newly stratified water columns.

In 1948, Sverdrup returned to Norway to direct the Norwegian Polar Institute. Shortly after, he became professor of geophysics in Oslo (followed by other senior university positions), director of the Norwegian-British-Swedish Scientific Expedition to Antarctica (1949–1952), and chairman of a Norwegian program to improve fishing technology in India. He died suddenly in August 1957.

Harald Sverdrup’s many appointments and honors included membership in the U.S. National Academy of Sciences and the Norwegian Academy of Sciences. He became a member of the Swedish Order of the North Star and was awarded the Agassiz Medal of the National Academy of Sciences, the Medal of the Royal Geographical Society, and the Bruce Medal (among many). He was President of the International Association of Physical Oceanography and of the International Council for the Exploration of the Sea, Vice President of the American Geophysical Union (and chairman of its Division of Oceanography), and received an LL.D. from the University of California.

An honest, unassuming, pious, hard-working, humorous, and humane investigator of the atmosphere and the oceans, Sverdrup believed it was his duty to advance the prospects of the two nations he served, Norway and the United States, through research, teaching, and public service. His lasting reputation and the continued influence of his publications attest to his success.

—Eric L. Mills

Dalhousie University
Halifax, Nova Scotia, Canada