Jacob Bjerknes with his father Vilhelm Bjerknes, 1897Jacob and his wife Hedvig Bjerknes, née Borthen, Tivoli, Denmark, 1929
Jacob Aall Bonnevie Bjerknes (/ˈjɑːkəbˈbjɜːrknɪs/YAH-kəb BYURK-niss, Norwegian:[ˈjɑ̀ːkɔbˈbjæ̂rkneːs]; 2 November 1897 – 7 July 1975) was a meteorologist.[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 the Norwegian meteorologist Vilhelm 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 airship Norge. 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 phenomenon El Niño.
Background
Jacob Aall Bonnevie Bjerknes was born in Stockholm, Sweden. His father was the Norwegian meteorologist Vilhelm Bjerknes, one of the pioneers of modern weather forecasting.[4] His paternal grandfather was Norwegian mathematician and physicist Carl Anton Bjerknes. His maternal grandfather was Norwegian politician Jacob Aall Bonnevie, after whom he was named.[5][6]
Professional career
Bjerknes was part of a group of meteorologists led by his father, Vilhelm Bjerknes, at the University 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 of fronts, that is, sharply defined boundaries between air masses. This concept is known as the Norwegian cyclone model.[7]
Bjerknes returned to Norway in 1917, where his father founded the Geophysical Institute, University of Bergen in Bergen. 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 meteorologists Carl-Gustaf Rossby and Tor 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 the University of Oslo in 1924.[3]
In 1926, Jacob Bjerknes was a support meteorologist when Roald Amundsen made the first crossing of the Arctic in the airship Norge. 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 the Massachusetts Institute of Technology during the 1933-1934 school year.
Bjerknes founded the UCLA Department of Meteorology (now the Department 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 accompany low-index conditions[clarification needed]. At UCLA, Bjerknes and fellow Norwegian-American meteorologist, Jorgen Holmboe, further developed the pressure tendency and the extratropical cyclone theories.
In 1969, Jacob Bjerknes helped toward an understanding of El 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]
Personal life
In 1928, he married Hedvig Borthen (1904–1998). They were the parents of two children. He died on 7 July 1975 in Los Angeles, California.[4]
