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Biographical Memoirs: Volume 68 (1995)

Chapter: Jacob Aall Bonnevie Bjerknes

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Suggested Citation:"Jacob Aall Bonnevie Bjerknes." National Academy of Sciences. 1995. Biographical Memoirs: Volume 68. Washington, DC: The National Academies Press. doi: 10.17226/4990.
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Suggested Citation:"Jacob Aall Bonnevie Bjerknes." National Academy of Sciences. 1995. Biographical Memoirs: Volume 68. Washington, DC: The National Academies Press. doi: 10.17226/4990.
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Suggested Citation:"Jacob Aall Bonnevie Bjerknes." National Academy of Sciences. 1995. Biographical Memoirs: Volume 68. Washington, DC: The National Academies Press. doi: 10.17226/4990.
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Suggested Citation:"Jacob Aall Bonnevie Bjerknes." National Academy of Sciences. 1995. Biographical Memoirs: Volume 68. Washington, DC: The National Academies Press. doi: 10.17226/4990.
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Suggested Citation:"Jacob Aall Bonnevie Bjerknes." National Academy of Sciences. 1995. Biographical Memoirs: Volume 68. Washington, DC: The National Academies Press. doi: 10.17226/4990.
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Suggested Citation:"Jacob Aall Bonnevie Bjerknes." National Academy of Sciences. 1995. Biographical Memoirs: Volume 68. Washington, DC: The National Academies Press. doi: 10.17226/4990.
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Suggested Citation:"Jacob Aall Bonnevie Bjerknes." National Academy of Sciences. 1995. Biographical Memoirs: Volume 68. Washington, DC: The National Academies Press. doi: 10.17226/4990.
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Suggested Citation:"Jacob Aall Bonnevie Bjerknes." National Academy of Sciences. 1995. Biographical Memoirs: Volume 68. Washington, DC: The National Academies Press. doi: 10.17226/4990.
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Suggested Citation:"Jacob Aall Bonnevie Bjerknes." National Academy of Sciences. 1995. Biographical Memoirs: Volume 68. Washington, DC: The National Academies Press. doi: 10.17226/4990.
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Suggested Citation:"Jacob Aall Bonnevie Bjerknes." National Academy of Sciences. 1995. Biographical Memoirs: Volume 68. Washington, DC: The National Academies Press. doi: 10.17226/4990.
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Suggested Citation:"Jacob Aall Bonnevie Bjerknes." National Academy of Sciences. 1995. Biographical Memoirs: Volume 68. Washington, DC: The National Academies Press. doi: 10.17226/4990.
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Suggested Citation:"Jacob Aall Bonnevie Bjerknes." National Academy of Sciences. 1995. Biographical Memoirs: Volume 68. Washington, DC: The National Academies Press. doi: 10.17226/4990.
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Suggested Citation:"Jacob Aall Bonnevie Bjerknes." National Academy of Sciences. 1995. Biographical Memoirs: Volume 68. Washington, DC: The National Academies Press. doi: 10.17226/4990.
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Suggested Citation:"Jacob Aall Bonnevie Bjerknes." National Academy of Sciences. 1995. Biographical Memoirs: Volume 68. Washington, DC: The National Academies Press. doi: 10.17226/4990.
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Suggested Citation:"Jacob Aall Bonnevie Bjerknes." National Academy of Sciences. 1995. Biographical Memoirs: Volume 68. Washington, DC: The National Academies Press. doi: 10.17226/4990.
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Suggested Citation:"Jacob Aall Bonnevie Bjerknes." National Academy of Sciences. 1995. Biographical Memoirs: Volume 68. Washington, DC: The National Academies Press. doi: 10.17226/4990.
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Suggested Citation:"Jacob Aall Bonnevie Bjerknes." National Academy of Sciences. 1995. Biographical Memoirs: Volume 68. Washington, DC: The National Academies Press. doi: 10.17226/4990.
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Suggested Citation:"Jacob Aall Bonnevie Bjerknes." National Academy of Sciences. 1995. Biographical Memoirs: Volume 68. Washington, DC: The National Academies Press. doi: 10.17226/4990.
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Suggested Citation:"Jacob Aall Bonnevie Bjerknes." National Academy of Sciences. 1995. Biographical Memoirs: Volume 68. Washington, DC: The National Academies Press. doi: 10.17226/4990.
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Suggested Citation:"Jacob Aall Bonnevie Bjerknes." National Academy of Sciences. 1995. Biographical Memoirs: Volume 68. Washington, DC: The National Academies Press. doi: 10.17226/4990.
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JACOB AALL BONNEVIE BJERKNES November 2, 1897-July 7, 1975 BY ARNT ELIASSEN JACOB AALE BONNEVIE BJERKNES, or Jack Bjerknes as he was usually called, was one of the founders of modern me- teorology. He entered the scientific scene at the age of twenty with the discovery of the structure of extratropical cyclones, which became of the greatest importance and formed the starting point of a fruitful development for theo- retical meteorology as well as practical weather forecasting. It was Jack's father, the famous physicist and geophysicist Vilhelm Bjerknes, who set the stage for the research lead- ing up to this discovery, but Jack was the principal per- former. FAMILY BACKGROUND The name Bjerknes comes from a family farm in south- eastern Norway where some of Jack's ancestors livecI. Jack represented the thirct generation in a dynasty of scientists. His grandfather, Carl Anton Bjerknes, was professor of math- ematics at the University of Christiania, as the Norwegian capital OsIo was called at the time. He showed both theo- retically and by experiment that an icleal fluid wouIc! trans- fer Coulomb-type forces between pulsating spheres and thought that he was on the track of a hyciroclynamical ether theory of electromagnetism. 3

4 BIOGRAPHICAL MEMOIRS Jack's father, Vilhelm Bjerknes, began his career as a physi- cist working with Heinrich Hertz in Bonn on electromag- netic resonance. In ~ 893 he married Honoria Sophia Bonnevie, a Norwegian science student in Christiania. They settled in Stockholm, where Vilhelm Bjerknes was appointee! lecturer ant! later professor of mechanics and mathemati- cal physics. Jack Bjerknes was born in Stockholm ant! spent his chilcI- hooc3 years there. He was namer! after his mother's father, Jacob Aall Bonnevie a prominent civil servant and minister ~ . . - --, ~ r--------- ot ectucat~on in Norway. Jack's aunt, Kristine Bonnevie, was Norway's first woman professor; her field was zoology. Young Jack thus grew up in an academic family. In ~ 897, the year Jack was born, his father, Vilhelm Bjerknes, discovered the circulation theorem that bears his name. It generalizes Helmholtz's and Kelvin's theorem on vortex conservation in ideal fluids into a theorem on vor- tex formation in nonhomogeneous fluids. With this theo- rem, Vilhelm Bjerknes realized that he now was in posses- sion of the complete set of hyciroclynamic/thermoclynamic equations that govern the motion of nonhomogeneous flu- ids. Encouraged by his Swedish colleagues, among them the famous chemist Svante Arrhenius en c! the oceanogra- pher Otto Petterson, he set out to apply the theory to the motions in the atmosphere and the sea. He put forward the view that weather forecasting should be clealt with as an initial valise problem of m~them~tic~1 nEvcirc and r~rrier1 out by numerical or graphical integration of the governing equations. This is nothing more than treating the atmo- `_ V sphere as a physical system; but at the time it was a revolu- tionary iclea. Vilhelm Bjerknes visited! the United States in 1905. At the initiative of the renowned American meteorologist Cleve- land Abbe, he gave a lecture in Washington, D.C., where he

JACOB AALL BONNEVIE BJERKNES 5 described his vision of scientific weather prediction. The lecture was enthusiastically received and resulted in a yearly grant from the Carnegie Institution of Washington, which he retainer! until the Second World War. The money could hardly have fount! a better use; it enabled ViThelm to em- ploy and educate a consiclerable number of research assis- tants, all of whom became well-known geophysicists. In ~ 907, when Jack was nine, the family moved to Christiania, where Vilhelm was called to a chair at the uni- versity. In cooperation with his Carnegie assistants, the Swecle Johan Sancistrom, ant! the Norwegians Olaf Devik and Theoclor Hesselberg, he published a substantial work, Dy- namic Meteorology and Hydrography. In Germany they were impressed and offered him a position as director of a new geophysics institute at the University of Leipzig. He accepted and with his family moved to Leipzig in 1913. Jack, how- ever, stayer! in Christiania to finish junior college and begin science studies at the Norwegian university. IN LEIPZIG DURING WORLD WAR I The Geophysics Institute in Leipzig started out success- fully. ViThelm Bjerknes brought with him his two Carnegie assistants, T. Hesselberg (later director of the Norwegian Meteorological Institute) and H. U. Svercirup (later clirec- tor of the Scripps Oceanographic Institution). In adclition, there were several German doctoral students ant! research assistants, among them Robert Wenger, who followed Bjerknes as director of the Leipzig institute. Then WorIct War ~ broke out, and many of the German students and staff were called to war service. Sverdrup en cl Hesselberg also left, and ViThelm Bjerknes was in great need of help for his research. In 1916 lack Bjerknes, not yet nineteen, interrupted his studies in Norway and went to Leipzig to join his family

6 BIOGRAPHICAL MEMOIRS and assist his father. With him went another Norwegian student, Halvor Solberg. In Leipzig a German cloctoral student, Herbert PetzoIcI, had been studying convergence lines in the wine! f~elct. But PetzoIcT was sent to the front and was killed at Verdun in 1916. Jack Bjerknes took over his research. He found that convergence lines may be thousands of kilometers long, tent} to drift eastward, and are connecter! with clouds anc! precipitation. He reported these results in his first scien- tif~c paper, which appeared in print before he was twenty. As the war went on, the situation for the Leipzig Geo- physics Institute worsened, with lack of labor and food short- ages. Through the intervention of the Norwegian oceanog- raphers Fridtjof Nansen anct Bj0rn HelIand-Hansen, a professorship was established for Vilhelm Bjerknes in Bergen in western Norway. THE BERGEN SCHOOL There was no university in Bergen at the time; but plans for a science faculty existed, ant} Bergen Museum served as a nucleus for such a clevelopment. HelIancI-Hansen held a position as professor of oceanography at Bergen Museum; he had for many years given international courses in ocean research. The establishment in 1917 of a new geophysics institute at Bergen Museum with a professorship for Vilhelm Bjerknes was an important step toward strengthening the academic milieu in Bergen. ViThelm Bjerknes left wartime Germany and arriver! in Bergen in the summer of 1917 with two young assistants, Jack Bjerknes and Halvor Solberg. He reaTizecl that he wouic! not have in Bergen the resources for a theoretical attack on the problem of weather prognosis and planned instead a push toward practical weather forecasting by offering a spe- cial summer forecasting service for agriculture. With sup-

JACOB AALL BONNEVIE BJERKNES 7 port from the Norwegian government, he arranged for a nearly tenfold increase in the number of observing stations in southern Norway. With these preparations, the forecasting started in the summer of 1918. Vilhelm Bjerknes clict not himself take part in the map work but arranger! to have Jack as fore- caster in Bergen and Solberg in Christiania. The war was still on, and no weather data were received from France, England, or the Atlantic. From the improved data network in Norway, however, Jack could again identify convergence lines of the type he tract studied in Leipzig, as they mover! along the Norwegian coast. Moreover, he cliscovere(1 that these convergence lines, which were later termed fronts, were connected with cyclones in characteristic manner. In a paper ("On the Structure of Moving Cyclones") written in the fall of 1918 before he was twenty-one, he presented his famous frontal cyclone model (see Figure I). The fronts in the mocle} were assumed to represent boundary surfaces separating cold air to the north and west of the cyclone center from warm air in the warm sector to the south anct southeast. These frontal boundary surfaces were assumed to be sloping with the coin air on the unclersicle, in accor- clance with a formula derives! in 1903 by the Austrian me- teorologist Max MarguTes. Furthermore, Jack stated in his paper that warm air ascends along the sloping frontal sur- · faces, causing bancis of clouds and precipitation to form along the fronts, whereas the coicI air sinks en cl spreads out along the ground. He notecl that these vertical motions represent a reduction of the potential energy, which couIcI account for the formation of the cyclone's kinetic energy, in agreement with MarguTes's theory publishecl fifteen years earlier. Jack also mentioned in his paper the notion of cy- clone series following the same path, with the trailing coin front after one cyclone serving as a warm front of a new

8 BIOGRAPHICAL MEMOIRS ~orikOr~ Sutton ~ ~ ~ r ~ - ~ ~ H~ ^ ~ `~` ~ =? ~ ;~ ~ ~~ ~ ~ _ ~ ~ ^ / /` -7-~--~ / ~ /~. 31 ~ .. \ : ~ `_ . \ ~ ;, . ~ . ~.;# ~ SoJ1~# steno , ~ an, ~,,~,,5~, ' ~ ~ ~ ~ . ce.~L .._ Cat ~ I-... ^ _ ~~" IS _~_ #__ _ ~` ~ ., ~ ,. an ~:~.~,~...~ ~11 ~ _I ~ -~ ~~ < >> A'' ~ ~ / ~ .\ { i. ~ . ~ , , ~ ~ / ~ ~ ado ~ ~ ~ Cold: TFo~~ ~ Cold ~> u~ ale eri\, line FICLRE 1 jack Weakness cyclone model ~reamUnes, clouds, and precipF tadon and verOca1 cros~secdons north and south of the center. (From ~erknes, 191~) cyclone briber west He even discussed the role of cyclones in the general circulation of the atmospbere and ascribed to them ~ role as ~ link in the interchange of a~ be~een the polar regions and the equatorial zone. On the wbole,]~ck~ short paper of eight pages contained

JACOB AALL BONNEVIE BJERKNES 9 an abundance of very interesting thoughts and suggestions. It was a fantastic achievement for a twenty year old after a few months of work with weather maps from a limited part of Europe. In the following years, Jack Bjerknes's frontal cyclone mode! was subject to intense study by the team consisting of Jack, Solberg, and Tor Bergeron, a Swedish student who joined the Bergen team in ~ 9 ~ 9. Solberg reanalyzed old weather maps from the AtIantic with many observations from ships. He found evidence that a polar front exists as an undulat- ina line across most of the ocean, with new cyclones form- ing as growing waves on the front. Bergeron found that in a later stage of the cyclone's life, the cold front will overtake the warm front, lifting the warm sector air to higher levels, whereas the cold air spreads out along the ground. This process he called occlusion. The Bergen team could now formulate a four-dimensional cyclone model, with a typical structure and a typical life cycle. As Theodor Hesselberg put it: "EThe cyclone] is born as Solberg's initial wave on the polar front, develops into Jack Bjerknes's ideal cyclone, and finally suffers the Rer~eroni~n orcl,,sion death." It is noteworthy, however, that many of the features of the life cycle of cyclones were already contained in Jack's original paper, which he wrote in the fall of 1918. In 1920 Jack Bjerknes was appointed head of the Weather Forecasting Office for western Norway. Here weather map analysis and forecasting were based on the frontal cyclone model. The frontal positions give information about winds, temperature, clouds, and precipitation; moreover, the shape of a frontal cyclone is indicative of its stage of development and can thus give information about its future behavior. The frontal cyclone model thus turned out to be an ex- tremely useful too! in weather forecasting.

0 BIOGRAPHICAL MEMOIRS So far, the cyclone moclel was mainly based on observa- tions from the ground; its vertical structure was mostly in- ferrect from theory. In 1922 Jack Bjerknes went to Zurich in SwitzerIanct as an invites! consultant to the Swiss Meteoro- logical Institute. By means of ciata from mountain peak ob- servatories in the Alps, he conic! verify the existence of sloping frontal surfaces up to an altitude of 3,000 meters. For the paper he wrote about this investigation, he was awarder! the degree of cloctor of philosophy by the Univer- sity of OsIo in 1924. In 1928 Jack married Hecivig Borthen, daughter of a well- known ophthalmologist in Bergen. After some years, Jack and He~vig settled into a house in Hop, south of Bergen, built on a lot bought from Hecivig's father. . ~ . · . . THE UPPER WAVE In the 1920s further exploration of air flow at higher elevations was hampered by lack of observations from these levels. However, cluring three consecutive clays in Decem- ber 1928 when two cyclones passed over Europe, P. Jaumotte, director of the Royal Belgian Meteorological Institute, launched thirty-one instrumented balloons at Uccle, Bel- gium. Of these, twenty-f~ve were recovered. The recordings were analyzed by Jack Bjerknes, and the results were given in a naner that was one of his most brilliant. It contains the upper- tropospheric westerlies, which are connected with the cy- clones at Tow levels. The wave trough was found to be lo- 1 ~ ~ probably the first clescrintion of the waves in cased above the coIc! front at the ground, and the vorticity connected with this trough was correctly ascribed to verti- cal stretching as the warm air descends cold front surface. clown the sloping This is the first attempt toward a dy- namic treatment of the upper wave. In 1931 Jack left the leadership of the Weather Forecast-

JACOB AALL BONNEVIE BJERKNES 11 ing Office in Bergen to Sverre Petterssen ant] took over a professorship of meteorology that was established for him at the Bergen Museum. As racliosoncle ciata in the ~ 930s became sufficiently nu- merous to make possible a.systematic diagnosis of the mo- tions in the upper troposphere, Jack was quick to exploit these new possibilities. In a number of papers, partly in cooperation with the Finnish geophysicist Erik Palmen, he constructed cross-sections through fronts en c! tropopause en c! showed how the coIcI front surface of one cyclone turns into the warm front of the next. In a paper from 1937 he pointed to the meridional gradient of the Coriolis param- eter as an important quantity in the dynamics of upper waves. This work inspired CarI-Gustaf Rossby to derive his celebratecl wave formula. A close collaborator of iack's in the 1930s was Car! Lu~vig Gociske, Vilhelm Bjerknes's Carnegie assistant who later suc- ceeclecl Jack in the chair in Bergen. Godske ant! Jack wrote an interesting paper together on instability of fronts; and Godske wrote the greater part of an extensive volume titled Dynamic Meteorology and Weather Forecasting, coauthored by Gociske, Bergeron, Jack Bjerknes, and R. C. Bunc3gaarcI. The book was planned by Vilhelm Bjerknes in the 1930s but was delayed by WorIcl War TI and cti(1 not appear in print until 1959. lack Bjerknes's work in Bergen aroused the attention of his colleagues. He received visitors from many countries and went himself on trips to SwitzerIanct, England, the Neth- erIands, Germany, Canada, and the United States as an in- vited guest lecturer. . WAR YEARS In July 1939 Jack Bjerknes, with his family, went on what was supposed to be an eight-month lecture tour to the United

2 BIOGRAPHICAL MEMOIRS States. But on September ~ of that year, WorIct War II be- gan, and later came the German invasion of Norway. For lack Bjerknes and his family, this had the consequence that they stayed in America and became U.S. citizens. The threatening international situation macle it impera- tive for the Uniter] States to educate a consiclerable num- ber of meteorologists for military operations. Jack was asked to organize a training school for Air Force weather officers at the University of California. His wife recalls that he chose the Los Angeles campus for this undertaking in orcler to be near the Scripps Oceanographic Institution in LaJolIa; he was of the opinion that cooperation with oceanographers was important. In 1940 he joined the faculty of the Univer- sity of California at Los Angeles as professor of meteorol- ogy en cl head of the Section of Meteorology in the Depart- ment of Physics. He brought with him J0rgen Holmboe, a Norwegian meteorologist from the Bergen Weather Service who hacI spent three years in Rossby's department at MTT. During the war, Jack visited England, Italy, Hawaii, and Guam as a consultant to the U.S. Army Air Corps. A NEW METEOROLOGY DEPARTMENT In 1945 a new Department of Meteorology was establisher! at the University of California at Los Angeles, with Jack Bjerknes as chairman. The new department grew fast and soon became one of the worId's reacting centers of teaching and research in the atmospheric sciences. During the war, Jack, in collaboration with Holmboe, at- tempted to treat theoretically the problem of the growing cyclone with its associated upper wave. One cannot say they solved the problem, but they threw new light on it, and their work inspirer! their first cloctoral stuclent, Jule Charney, to come out with the first mathematical solution describing growing waves on a baroclinic current.

JACOB AALL BONNEVIE BJERKNES 13 It had been known for many years that the atmospheric westerlies in middle latitucles increased with height en c! usu- ally reached a maximum near the tropopause. For instance, a calculated distribution of the mean west wine! in the meridional plane is given in Physikailische Hydrodynamik, the volume publishecl by V. Bjerknes, J. Bjerknes, H. Solberg, ant! T. Bergeron in 1933. The improved winct measurements after the war revealer! that the upper westerlies the jet stream are often much stronger than previously assumed. How was this strong current circumventing the earth, one in each hemisphere, maintained against frictional clissipa- tion? The English mathematician ant! geophysicist HaroIcI J Jeffreys had aIreacly, in 1933, proposed an answer to this pressing question by suggesting that angular momentum could be transferred! from Tow to micicIle latitudes by atmo- spheric waves and ecldies. Basecl on Jeffreys's theory, Jack Bjerknes started a major research project on the general circulation of the atmosphere. His principal co-worker was Yale Mintz; but invites! scientists from many countries par- ticipated. They collected! ciata from the entire northern hemi- sphere ant! calculates! meridional fluxes of angular momen- tum and energy en cl many other statistics. The results verifier! TeffreYs's thesis and were in reasonable agreement with re- sults from Victor Starr and his group at MIT, who ran a similar project at the same time. Our quantitative knowI- etlge of the general circulation was greatly advanced by these two research projects. AIR-SEA INTERACTION ON A GLOBAL SCALE Toward the enc! of the 1950s, when Jack Bjerknes was around sixty, he turned his mind to a new f~elc! of research that engaged him for the rest of his life—the interaction of atmosphere and sea. Jack credits C. G. Rossby, H. U. Sverdrup, and Bj0rn

4 BIOGRAPHICAL MEMOIRS HelIancI-Hansen for giving him inspiration and encourage- ment to take up this new field. These three scientists all died in 1957, when lack was starting his oceanographic stud- ies. HelIand-Hansen belonged to an oicler generation; he had made pioneering studies of the Atlantic Ocean in co- operation with Fridtjof Nansen before and cluring WorIcl War T. Jack was his colleague in Bergen for twenty years and was familiar with his and Nansen's work. Jack first took up the study of the warming of the North Atian tic Ocean at the beginning of the century and found that it could be explained by an increased wind drag that speecled up the Gulf Stream. The interannual variations of the sea surface temperature in the North Atlantic were his next study subject. He cliscoverec! that these temperature variations are connected with the strength of the westerlies. Years with particularly strong westerly wincis in micicIle lati- tudes wouicl clisplay a typical pattern of sea surface tem- perature anomalies, with unusually cold water south of Tce- lancl ant! GreenIan(1 and warmer water in the Gulf Stream outside the Grand Banks. In a series of papers he discussed the physical processes involved and gave qualitative expla- nations of the observed anomalies of the sea surface tem- peratures. Jack's studies of the Pacific Ocean are even more remark- able. He began with an investigation of the El Nino phe- nomenon. Once every two to five years the coo! nutrition- rich waters off the coast of Peru are replaced in the Southern Hemisphere summer by warmer sterile water, with a cata- strophic result for Peruvian fishing and production of guano fertilizer from sea birds. These episodes are known as E} Nino (the Holy Child, since they usually set in at Christmas time) . Jack found that El Nino is not a local phenomenon con- fined to the Peruvian coast but the manifestation of an

JACOB AALL BONNEVIE BJERKNES 15 oscillatory process that affects the atmosphere and the ocean over the entire tropical Pacific. During the E! Nino years, a huge area of the eastern ant! middle equatorial Pacific may be as much as 2 K warmer than normal. To the atmosphere, such a disturbed Pacific Ocean must represent a very strong aciclitional source of heat and moisture. The immediate ef- fect is increaser! rainfall locally in the region of warm sea surface. But lack also looked for manifestations of a strength- ened HacIley circulation, and he found an increased west winc3 in the northern Pacific, with distant effects on the weather in North America en cl possibly also in Europe. These teleconnections over large distances recurred! when new El Nino episodes occurred. Jack also established a connection between the El Nino phenomenon en c! the southern oscillation, an irregular pul- sation of atmospheric pressure between the Pacific and the Indian Oceans cTiscoverecl by Sir Gilbert Walker in the 1920s. To account for variations in rainfall, Jack envisaged a verti- cal air circulation along the equator in the Pacific area, which he called the Walker circulation, since its strength would vary with Walker's southern oscillation. As a result of his investigations, we now have a coherent picture of these large-scare processes in the equatorial Pacific. Jack Bjerknes's research on air-sea interactions is particu- larly important because these processes play an essential role in the theory of climate. Today, when the earth's cTi- mate is being threatened by human activities, research aim- ing at predicting possible climate changes is carried on vig- orously in many countries. Such research, which is so vitally important to humankind, can build on Jack's results and the wealth of icleas contained in his papers. CONCLUSION Jack Bjerknes was active as a scientist for more than fifty-

16 BIOGRAPHICAL MEMOIRS five years. He was a modest en cl kincI man, always generous with his time to listen to the problems of students and col- leagues ant! always comforting them with his wise course! ant! guidance. But he never wasted his time. His waking hours were clevotect to work ant! studies of his problems, never in a great hurry but never stopping. He was very persistent; when he took up a problem, he would not let go of it until he hac! clone his utmost to have it clarified. Through the years many friends and colleagues enjoyed Jack and Hecivig's hospitality in their Santa Monica home. They also kept a house outside Bergen and often spent their holidays in Norway. Jack hell! contact with Norwegian colleagues, many of whom were invites! to UCLA as visiting · ~ scientists. More than any other atmospheric scientist, Jack Bjerknes managed to create order and system in a seemingly disor- clerly atmosphere. It is most remarkable that after seventy- five years his frontal cyclone mode! is still used as a princi- pal too! in the worIcl's weather services. Nobocly knows how many lives have been saved through the years as a result of the improved methods of weather forecasting that Jack Bjerknes instituted. IN PREPARING THIS MEMOIR I received very useful information and advice from Mrs. Hedvig Bjerknes and from Professors Morton G. Wurtele and Akio Arakawa. I also used information extracted from Robert Marc Friedman's book, Appropriating the Weather (Cornell University Press, Ithaca, N.Y., 1989~. A very useful selection of lack Bjerknes's papers, with a complete bibliography, was published by M. G. Wurtele (Selected Papers of Jacob Call Bonnevie Bjerknes, Western Periodicals Co., North Hollywood, Calif., 1975~.

JACOB AALL BONNEVIE BJERKNES HONORS AND DISTINCTIONS Honorary Fellow, Royal Meteorological Society, 1932 Symons Medal, Royal Meteorological Society, 1940 Bowie Medal, American Geophysical Union, 1945 Meritorious Civilian Service Medal, U.S. Air Force, 1946 Royal Norwegian Order of St. Olav, 1947 Vega Medal, Swedish Society of Geography, 1958 International Meteorological Organization Prize, World Meteorological Organization, 1959 Carl-Gustaf Rossby Award, American Meteorological Society, 1960 Robert M. Losey Award, Institute of Aerospace Sciences, 1963 President, Meteorological Association, International Union of Geodesy and Geophysics, 1948-51 National Medal of Science, 1966 Honorary Member and Fellow, American Meteorological Society, 1966 Honorary Doctor of Laws, University of California, 1967 Member, Royal Norwegian Academy of Sciences, Royal Swedish 17 Academy of Sciences, Danish Academy of Technical Sciences, Academy of Sciences (India), American Academy of Arts and Sciences, and National Academy of Sciences

8 BIOGRAPHICAL MEMOIRS SELECTED BIBLIOGRAPHY 1917 Uber die Fortbewegung der Konvergenz und Divergenzlinien. Meteorol. Z. pp. 345-49. 1919 On the structure of moving cyclones. Geofys. Publ. I(2~. 1921 With H. Solberg. Meteorological conditions for the formation of rain. Geofys. Publ. II(3~. 1923 With H. Solberg. Life cycle of cyclones and the polar front theory of atmospheric circulation. Geofys. Publ. III(1~. 1924 Diagnostic and prognostic application of mountain observations. Geofys. Publ. III (6~. 1930 Practical examples of polar front analysis over the British Isles in 1925-26. Geophysi ca I Memoirs N o . 50. 1932 Exploration de quelques perturbations atmospheriques a l' aide de sondages rapproches dans le temps. Geofys. Publ. IX(91. 1935 La circulation atmospherique dans les latitudes soustropicales. Scienta LVII(225~:114-23. 1936 With C. L. Godske. On the theory of cyclone formation at extra- tropical fronts. Astrophys. Norv. I(6~:199-235.

JACOB AALL BONNEVIE BJERKNES 1937 19 With E. Palmen. Investigation of selected European cyclones by means of serial ascents. Geofys. Publ. XII(2~. Theorie derAussertropischen Zyklonenbildung. Meteorol. Z. 54~12~:462- 66. 1938 Saturated-adiabatic ascent of air through dry-adiabatically descend- ing environment. Q. [. R. Meteorol. Soc. 64:325-30. 1944 WithJ. Holmboe. On the theory of cyclones.J. Meteorol. I(1~:1-22. 1948 Practical application of H. Jeffreys' theory of the general circula- tion. In Resume des Memoires Reunion d 'Oslo, pp. 13-14. 1951 The maintenance of the zonal circulation of the atmosphere. In Proces-Verbaux des Seances de ['Association de MeterologZe. Bruxelles. 1954 The difluent upper trough. Arch. Meteorol. Geophys. Bioklimatol. A 7:41-46. 1955 The transfer of angular momentum in the atmosphere. In Scientific Proceedings of the International Association of Meteorology, pp. 407-8. 1957 Detailed Analysis of Synoptic Weather as Observed from Photographs Taken on Two Rocket Flights over White Sands. Paper P-887. Santa Monica, Calif.: Rand Corporation. With S. V. Venkateswaran. A Model of the General Circulation of the Tropics in Winter. Final report, General Circulation Project, Contract No. AF 19~604~-1286, U.S. Air Force Cambridge Re- search Center.

20 BIOGRAPHICAL MEMOIRS 1959 The recent warming of the North Atlantic. In Rossby Memorial Vol- ume, ed. B. Bolin, pp. 65-73. New York: Rockefeller Institute Press in association with Oxford University Press. 1960 Ocean temperatures and atmospheric circulation. WMOBull.IX(3~:151- 57. 1961 E1 Nino, Study based on analysis of ocean surface temperatures 1935-57. Bull. Inter-am. Tropic. Tuna Comm. 3:219-303. Climatic change as an ocean-atmosphere problem. In Proceedings of the Rome Symposium, organized by UNESCO and the World Me- teorological Organization, pp. 297-321. UNESCO. 1962 Synoptic survey of the interaction of sea and atmosphere in the North Atlantic. Geofys. Publ. XXIV(3~:115-45. 1964 Atlantic air-sea interaction. In Advances in Geophysics 10:1-82. New York: Academic Press. 1966 A possible response of the atmospheric Hadley circulation to equa- torial anomalies of ocean temperature. Tellus XVIII (4) :820-29. Atmospheric teleconnections responding to equatorial anomalies of ocean temperature. In Proceedings of the Symposium on the Arctic Heat Budget and Atmospheric Circulation, Lake Arrowhead, Calif., Jan. 31-Feb. 4. Rand Memorandum No. RM-5233-NSF, pp. 473- 96. 1969 Atmospheric teleconnections from the Equatorial Pacific. Mon. Weather Rev. 97~3~:163-72. 1972 Global ocean-atmosphere interaction. In Rapports et Proces-Verbaux,

lACOB AALL BONNEVIE BJERKNES vol. 162, pp. the Sea. 108-99. International Coun 21 .cil for the Exploration of Large-scale atmospheric response to the 1964-65 Pacific equatorial warm i ng. I. Phys. Oceanogr. 2 ( 3 ): 2 1 2- 1 7 . 1974 Atmospheric Teleconnections from the Equatorial Pacific During 1963-67. Final report to the National Science Foundation under NSF Grant No. GA 27754, pp. 1-66.

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Biographic Memoirs: Volume 68 contains the biographies of deceased members of the National Academy of Sciences and bibliographies of their published works. Each biographical essay was written by a member of the Academy familiar with the professional career of the deceased. For historical and bibliographical purposes, these volumes are worth returning to time and again.

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