Jacob Bjerknes | |
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| Born | (1897-11-02)2 November 1897 Stockholm, Sweden |
| Died | 7 July 1975(1975-07-07) (aged 77) Los Angeles, United States |
| Citizenship | Norwegian / American |
| Known for | ENSO Norwegian cyclone model Weather forecasting |
| Awards | National Medal of Science (1966) Carl-Gustaf Rossby Research Medal (1960) International Meteorological Organization Prize (1959) Guggenheim Fellowship (1957) William Bowie Medal (1945) Symons Gold Medal (1940) Vega Medal (1939) |
| Scientific career | |
| Fields | Meteorologist |
| Institutions | University of California, Los Angeles |
Jacob Aall Bonnevie Bjerknes (/ˈjɑːkəbˈbjɜːrknɪs/YAH-kəbBYURK-niss,Norwegian:[ˈjɑ̀ːkɔbˈbjæ̂rkneːs]; 2 November 1897 – 7 July 1975) was ameteorologist.[1][2] He is known for his key paper in which he pointed the dynamics of the polar front, mechanism for north-south heat transport and for which he was also awarded a doctorate from the University of Oslo.[3]
Born in Stockholm, Sweden, he was the son of theNorwegian meteorologistVilhelm Bjerknes, one of the pioneers of modern weather forecasting.[4] He helped develop the Norwegian cyclone model. He earned a Ph.D. from the University of Oslo in 1924. Bjerknes was part of the team that made the first crossing of the Arctic in the airshipNorge. During WWII, he helped the US with the planning of the Hiroshima and Nagasaki atomic bombings. He also helped gain an understanding of the weather phenomenonEl Niño.
Jacob Aall Bonnevie Bjerknes was born inStockholm, Sweden. His father was theNorwegian meteorologistVilhelm Bjerknes, one of the pioneers of modern weather forecasting.[4] His paternal grandfather was Norwegian mathematician and physicistCarl Anton Bjerknes. His maternal grandfather was Norwegian politicianJacob Aall Bonnevie, after whom he was named.[5][6]
Bjerknes was part of a group of meteorologists led by his father, Vilhelm Bjerknes, at theUniversity of Leipzig. Together they developed the model that explains the generation, intensification and ultimate decay (the life cycle) of mid-latitude cyclones, introducing the idea offronts, that is, sharply defined boundaries between air masses. This concept is known as theNorwegian cyclone model.[7]
Bjerknes returned to Norway in 1917, where his father founded theGeophysical Institute, University of Bergen inBergen. They organized an analysis and forecasting branch which would evolve into a weather bureau by 1919. The scientific team at Bergen also included the Swedish meteorologistsCarl-Gustaf Rossby andTor Bergeron. As pointed out in a key paper by Jacob Bjerknes and Halvor Solberg (1895-1974) in 1922, 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 Bjerknes was awarded the Ph.D. from theUniversity of Oslo in 1924.[3]
In 1926, Jacob Bjerknes was a support meteorologist whenRoald Amundsen made the first crossing of the Arctic in the airshipNorge. In 1931, he left his position as head of the National weather service at Bergen to become professor of meteorology at the Geophysical Institute at the University of Bergen. Jacob Bjerknes lectured at theMassachusetts Institute of Technology during the 1933-1934 school year.
In 1940, he emigrated to theUnited States, where he headed a government-sponsored meteorology annex for weather forecasting, at the department of physics of theUniversity of California, Los Angeles. During theSecond World War Bjerknes was in theUS armed forces, and serving as a colonel in the US Air Force he helped determine the best dates for theatomic bombings of Hiroshima and Nagasaki.[8]
Bjerknes founded theUCLA Department of Meteorology (now theDepartment of Atmospheric and Oceanic Sciences). As a professor at the University of California, he was the first to see a connection between unusually warm sea-surface temperatures and the weak easterlies and heavy rainfall that accompanylow-index conditions[clarification needed]. At UCLA, Bjerknes and fellow Norwegian-American meteorologist,Jorgen Holmboe, further developed the pressure tendency and theextratropical cyclone theories.
In 1969, Jacob Bjerknes helped toward an understanding ofEl Niño Southern Oscillation, by suggesting that an anomalously warm spot in the eastern Pacific can weaken the east-west temperature difference, disrupting trade winds, which push warm water to the west. The result is increasingly warm water toward the east.[9]
In 1928, he married Hedvig Borthen (1904–1998). They were the parents of two children. He died on 7 July 1975 inLos Angeles, California.[4]
He was made an Honorary Member of theRoyal Meteorological Society in 1932 and a member of both theNorwegian Academy of Science and Letters and theRoyal Swedish Academy of Science in 1933.
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