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Sverre Petterssen (1898–1974)

Basic Facts

  • Born: 19 February 1898, Hadsel Municipality, Lofoten Islands, Norway
  • Died: 31 December 1974, London, England (sudden heart attack)
  • Nationality: Norwegian; US citizen from March 1955; relinquished US citizenship 1973
  • Fields: Synoptic and dynamic meteorology, weather forecasting, wartime meteorology

Family and Early Life

Born into a humble fishing community family in the Lofoten Islands of northern Norway. His mathematical aptitude earned him a scholarship for secondary studies in physical sciences. He financed his higher education by working at a telegraph office and in a nursery operated by the armed forces, where he served as a recruit.

Marriages:

  • First marriage: dissolved 1939; produced two children (son in Boston, daughter in Norway)
  • Second marriage: September 1941–October 1942 (divorce finalized April 1947)
  • Third marriage: June 1946, to Grace; they lived together in London during his final years

Health: Suffered a heart attack in 1957.

Citizenship drama: Relinquished US citizenship in 1973, reportedly disillusioned with the White House administration during the Vietnam War and Watergate, without reactivating Norwegian citizenship.

Education

  • 1915–1918: Army school; achieved rank of sergeant
  • BSc, University of Oslo (1924)
  • MSc, University of Oslo (1926)
  • PhD, University of Oslo (1933) – thesis on pressure field kinematics

Career Timeline

  • Summer 1923: Attended a four-week international meteorological seminar in Bergen organized by Vilhelm Bjerknes. The pivotal moment: instructor Tor Bergeron presented maps of a dramatic October 1921 storm that Bjerknes’s methods had successfully predicted. This experience inspired Petterssen to pursue meteorology.
  • 1923: Joined the Bergen School of Meteorology.
  • Late 1920s: Worked at the Geophysical Institute in Tromso, northern Norway.
  • 1928: Provided weather advice for the Nobile polar expedition. Explorer Umberto Nobile ignored Petterssen’s warning about adverse conditions. The resulting disaster led to deaths, including Roald Amundsen’s (who died in a rescue attempt).
  • 1931: Regional director for western Norway (Bergen); prominent foreign meteorologists visited.
  • 1935: Spent nearly a year lecturing across North America (US Navy, Caltech).
  • 1939: Hired by MIT as head of the meteorology department, replacing Carl-Gustaf Rossby.
  • 1940: Published Weather Analysis and Forecasting.
  • 1941: Published Introduction to Meteorology.

World War II (1941–1945)

  • August 1941: Exiled Norwegian government requested his assistance at the Central Forecasting Office in Dunstable, England. Held rank of officer in the Norwegian Air Force while functioning as a civilian.
  • 1942: Issued the forecast enabling the successful air attack against the German battleship Tirpitz, using childhood knowledge of Norwegian geography and reconnaissance photographs.
  • November 1942: Warned Norwegian commandos about adverse weather for the Vemork heavy-water facility raid. The group ignored his advice, resulting in failure (the gliders crashed in bad weather).
  • April 1944: Forecasted conditions for the Anzio invasion.
  • June 1944 – D-Day: Critical member of the British-American meteorological team advising General Eisenhower.

The D-Day Forecast

Petterssen’s analysis showed a storm on 5 June with a 36-hour gap between two storms on the morning of 6 June – just enough to make the massive attack with over 100000 soldiers, paratroopers, planes, and boats. He disagreed sharply with the American USAAF team of Irving P. Krick and Ben Holtzman, who believed weather patterns repeated cyclically. Petterssen considered their approach “nonsense and quasi-science,” though he communicated this view relatively diplomatically at the time. The invasion was postponed one day from 5 to 6 June based on the British team’s analysis.

Only in 1974, shortly before death, did Petterssen publicly document his version of D-Day events, including “a violent quarrel” with the American team. He also taught pilots about upper-level westerly winds, warning of winds potentially exceeding 100 m/s over Japan during winter 1945 operations.

Post-War Career

  • 1945–1948: Returned to Norway to reorganize and expand the Norwegian Weather Service, adapting the German telecommunications and radiosonde network established during occupation.
  • 1946–1951: President of the International Aerological Commission.
  • 1948–1952: Director of science services for the US Air Force Weather Service.
  • 1953–1963: Professor at the University of Chicago.
    • Founded the Weather Forecasting Research Center
    • Chaired the Department of Meteorology (1959–1961)
    • Chaired the Department of Geophysical Sciences (until retirement in 1963)
    • Developed research on storm dynamics, energetics, and jet-stream wave propagation
    • Collaborated with R.C. Sutcliffe on cyclone development theory
    • Published revised, two-volume edition of Weather Analysis and Forecasting (1956) – “unique in its combination of basic science and technical application”
  • 1955: Presented a development equation expressing four dynamical-physical processes crucial for cyclone development.
  • 1958–1959: President, American Meteorological Society.
  • 1962: Panelist on President Kennedy’s Scientific Advisory Committee for atmospheric sciences.
  • 1963–1965: Scientific attache to Scandinavian countries at the US Embassy in Stockholm.
  • 1965–1974: Lived in London, maintaining American university connections as invited lecturer through 1971.
  • 1971: With S.J. Smebye, identified two distinct extratropical cyclone development types (Type A: local influences; Type B: upstream forcing) – the “Petterssen-Smebye classification.”

Major Scientific Contributions

Frontogenesis Function

Petterssen developed a series of simple mathematical expressions for the velocity, acceleration, and rate of development of weather fronts and pressure centers at both surface and upper levels. The Petterssen frontogenesis function – defined as the Lagrangian rate of change of the magnitude of the horizontal potential temperature gradient – became the standard mathematical measure of frontal intensification and weakening. Introduced in 1936, it quantifies the kinematic processes influencing the strength of the potential temperature gradient over time. This supplied forecasters with workable computational tools.

Development Equation (1955)

Expressed four dynamical-physical processes crucial for cyclone development, later refined with Smebye (1971) into the classification of extratropical cyclone development types.

Textbooks

His Weather Analysis and Forecasting (1940, expanded 1956) was the standard reference bridging theoretical science and operational forecasting. It was “unique in its combination of basic science and technical application.”

Personal Characteristics

  • “A man of vitality, a lively philosopher, a bon vivant and a friendly humorous companion with an intriguing air of deep understanding and a neat turn of irony.”
  • Known for classroom wit and incisive commentary.
  • Said he “certainly had not got where he was by being methodical,” preferring knowledge with practical application and purpose.
  • Harbored “a sort of subliminal fear that the fun was over” as computerized forecasting replaced the meteorological maestro era.

Awards and Honors

  • 1948: Buys Ballot Gold Medal (Royal Netherlands Academy of Arts and Sciences)
  • 1951: USAF Distinguished Service Award
  • 1958–1959: President, American Meteorological Society
  • 1965: International Meteorological Organization Prize (World Meteorological Organization)
  • 1969: Symons Gold Medal (Royal Meteorological Society) – for “his outstanding contributions to the science of meteorology and weather forecasting”

Key Publications

  • Weather Analysis and Forecasting (1940; expanded 2-vol. edition 1956)
  • Introduction to Meteorology (1941; 2nd ed. 1958; 3rd ed. 1969)
  • “A General Survey of Factors Influencing Development at Sea Level” (1955)
  • “The Norwegian Cyclone Models in Relation to Heat and Cold Sources” with D.L. Bradbury and K. Pedersen (1962)
  • “On the Development of Extratropical Cyclones” with S.J. Smebye (1971)
  • Kuling fra nord (“Gale from the North: A Weather Forecaster’s Reminiscences”) (1974, Norwegian autobiography)
  • Weathering the Storm: Sverre Petterssen, the D-Day Forecast, and the Rise of Modern Meteorology (2001 English edition, edited by James Rodger Fleming)

Connections to Other People

  • Vilhelm Bjerknes: Mentor; organized the Bergen seminar that drew Petterssen into meteorology.
  • Tor Bergeron: Teacher whose 1922 storm analysis inspired Petterssen’s career; Petterssen joined Bergen School after attending Bergeron’s lecture.
  • Jacob Bjerknes: Predecessor in the Bergen regional director role; later colleague at various international meetings.
  • Carl-Gustaf Rossby: Petterssen replaced Rossby at MIT in 1939 when Rossby moved to the Weather Bureau and then Chicago. Petterssen later joined Chicago as well.
  • R.C. Sutcliffe: Wartime British colleague; later collaborated on cyclone development theory.
  • Irving P. Krick: Adversary during D-Day forecast – Petterssen viewed Krick’s analog method as “nonsense and quasi-science.”
  • James Murdoch Austin: Doctoral student.
  • James Rodger Fleming: Historian who edited and annotated Petterssen’s autobiography for English publication.

Sources