Conquering the Weather Bureau

More than anyone, it was Carl-Gustaf Rossby who finally dragged the U.S. Weather Bureau into the twentieth century. It was he who created the first American university programs in meteorology and set the nation on a course of scientific excellence. It was Rossby, more than anyone, who organized the emergency training of thousands of military meteorologists in time to contribute to the Allied victory of World War II. And it was Rossby whose own celebrated research opened the way to extended forecasting and helped achieve the century's great dream of numerically calculating the weather. Arriving in Washington, D.C., early in 1926, unheralded and all but unwelcome, the father of modern American meteorology was not an American but a Swede.

Sponsorship came privately from the American-Scandinavian Foundation, which granted the young meteorologist a fellowship to travel to the United States and to work at the Weather Bureau to study the application of the polar front theory to American weather. He was 27 years old and physically unimposing—he was short and had a round face— although he was vigorous and all of his life an uncommonly hard worker. In personality and intellect, Carl Rossby was everything that chief Charles F. Marvin and the other old men administering the Weather Bureau were not. He was trained in mathematics and physics and scientifically astute. He was brilliant, charming, persuasive, and relentlessly enthusiastic about spreading the new science of the Bergen school of meteorology across the United States. At the central office of the Weather Bureau, where these characteristics were not in great demand, the new visitor from Scandinavia was assigned a desk that was located in a far corner of the agency's library. Even this remote station would be withdrawn before long, and he would become persona non grata—an official posture, no doubt, which inspired false hopes by the U.S. weather bureaucrats that they had seen the last of Carl Rossby.

Born in 1898 in Stockholm, Carl was the first of five children of Arvid and Alma Charlotta Rossby. His father, a quiet and jovial man, was a construction engineer of modest means. His mother was the daughter of a wealthy pharmacist in Visby, which is located on Gotland, a Baltic Sea island famous for its orchids. Visits to Gotland, shared later with American friends, inspired an early interest in botany and a lifelong interest in orchids. To spend time with Rossby was to live in the wake of an electrifying personality. He was bursting with a delighted, infectious interest in many things, and he liked nothing better than sharing. But there was a private side to this thoroughly social creature. Even close friends did not know of his interest in music or his early talent at the piano. And some secrets were darker. Rossby did not share with friends the experience of his affliction with rheumatic fever as a boy or the medical knowledge that the disease had seriously damaged his heart.

Rossby obtained a bachelor's degree at the University of Stockholm in 1918, specializing in mathematics, astronomy, and mechanics, accomplishing in less than a year a course of studies that was supposed to require three. Professors noticed this young, precocious, inquisitive, restless student. In the winter of 1918-1919, when Vilhelm Bjerknes revisited the university while scouting Sweden for young talent to fill his needs at his new Geophysics Institute and weather forecasting service in western Norway, Rossby's name was high on the list. Eager for adventure, but without a stitch of education in meteorology, Carl Rossby arrived in Bergen during the exciting summer of 1919, just as the polar front theory was taking shape.

"This boy of 20 had an amazing persuasive and organizing faculty," Tor Bergeron would recall of Rossby's first days in Bergen. In a Rossby memorial volume, The Atmosphere and the Sea in Motion, Bergeron wrote "His far-reaching ideas and high-flying plans often took our breath away. Soon he was also able to make practical suggestions of value for the experimental weather service that was connected with the Geophysical Institute at Bergen." Still, for all the intellectual ferment of those days, Rossby may have felt somewhat out of place in Bergen. The engaging informality of those days, so different from the strict formalism of Swedish academia, was a style that Rossby would emulate everywhere he went, but this may have been the one occasion in his life when he did not feel intellectually in command of his subject. He was not especially well equipped for, or interested in, the routine technical mapping of data that was central to practical daily forecasting. At the same time, while he naturally gravitated toward theory, he lacked the knowledge of higherlevel mathematics and physics that might have allowed him to contribute some dynamical understanding to the work that was under way that summer. As Bergeron observed, "Rossby had not yet, at Bergen, found the time and place, and the branch of meteorology, where his special capacity as a scientist and organizer could prosper." Certainly he had fallen in love with the science of meteorology, and he was thoroughly indoctrinated in the new ways of air-mass analysis. After a year, however, he was ready to leave Bergen, to begin to find his own way, but first he had to secure more advanced scientific skills.

Following in Vilhelm Bjerknes's footsteps, Rossby went to the University of Leipzig, where the young Swede first encountered valuable data from direct soundings of the upper air. He spent part of 1921 near Berlin at the aeronautical observatory in Lindenberg, a center for kite and balloon observations. Later in 1921, he returned to the University of Stockholm to study more mathematical physics. To earn money for his education, he took a year off to work as a meteorologist with the Swedish weather service. During the summers, he served as the meteorologist aboard oceanographic expeditions. In 1923, he was on board the small Norwegian vessel SS Conrad Holmboe when it was caught in pack ice off the shores of eastern Greenland. For two months, the vessel was helpless and in danger of sinking. The cruise almost ended in disaster before help arrived. In 1925, Rossby obtained the equivalent of a master's degree in mathematical physics from the University of Stockholm, and his formal education came to an end. Rossby's intellectual restlessness got the better of him. The scientist who for 25 years would be the single most influential figure in meteorology in the United States never did obtain a doctorate.

After arriving in Washington, D.C., in 1926, Rossby soon found in meteorologist Richard H. Weightman one of the few people at the U.S. Weather Bureau interested in the new ideas from the Bergen school. The two collaborated on a paper that appeared in the December issue of the bureau's Monthly Weather Review: "Application of the Polar-Front Theory to a Series of American Weather Maps." A classic of its kind, the article concluded that their research "has furnished conclusive evidence that the polar front theory can be applied with great advantage to even rather complicated weather maps in the United States and that it enables us to explain phenomena which without a knowledge of the dynamics of the situation would hardly be understood."

This paper had no more impact on the Weather Bureau than any of the science appearing in its monthly publication. With missionary zeal, Rossby was preaching to men who were 40 years his senior, forecasters that meteorologist Horace R. Byers later would describe as "half-educated practitioners who had risen through the ranks because of some practical knowledge and ability to outguess the weather." In charge was Charles Marvin, an old bureaucrat who trained as an instrumentation engineer, and whose career in the agency dated back to the 1880s, when the weather service was part of the U.S. Army Signal Corps. In this deeply entrenched bureaucracy, neither Chief Marvin nor anyone else in authority saw reason to change the way the Weather Bureau had been doing things for decades. These men, observed Byers, "had no interest in Rossby's scientific brilliance but rather found the young Swede, with his schemes for revitalizing meteorology in the United States, a great nuisance."

Outside of the Weather Bureau, however, the burgeoning field of aviation was generating urgent new practical interest in the state of the science of meteorology in the late 1920s, and the advantages of the new forecasting methods of the polar front theory seemed obvious. Among the first to discover Rossby hidden away in the library was a young U.S. Navy lieutenant, Francis W. Reichelderfer, who was in charge of Naval Aerology and made daily data-gathering visits to the Weather Bureau to help prepare his own forecasts. Reichelderfer was delighted to find someone so familiar with Bergen school methods. The two young men, close in age, spent hours together after work in critiques of the day's weather maps. And Reichelderfer introduced Rossby to his friend Harry F. Guggenheim, president of the Daniel Guggenheim Fund for the Promotion of Aeronautics. Just as Rossby's American-Scandinavian Foundation grant was running out at the Weather Bureau, Harry Guggenheim, himself a World War I pilot, arranged to extend his financial support. It was Reichelderfer and Guggenheim who recognized Rossby's promise and set the stage for remaking meteorology in the United States.

Early in 1927, with Guggenheim's support, Rossby helped prepare weather forecasts when Richard E. Byrd crossed the Atlantic in the three-motored America with a crew of three a few weeks after Charles A. Lindbergh's famous solo flight to Paris in the Spirit of St. Louis. In July 1927, while still at the Weather Bureau, Rossby was named the full-time, paid chairman of the new Guggenheim-funded Interdepartmental Committee on Aeronautical Meteorology. From this position, he arranged to send a young and promising Weather Bureau employee, Hurd C. Willett, to a year of study in Bergen.

As Rossby's reputation began rising outside of the agency, what Byers described as "a series of minor incidents" in connection with his Guggenheim work led to increasing conflict with Marvin and other Weather Bureau administrators. The final incident came after Rossby received a call from Charles Lindbergh. Sponsored by Guggenheim, the new American hero had just completed a 48-state tour in the Spirit of St. Louis, landing in 100 towns across the country and preaching his vision of the future of aviation to millions of Americans. Now Lindbergh had been persuaded to attempt a 27-hour nonstop flight from Washington, D.C., to Mexico City. The famous pilot, whose low opinion of Weather Bureau forecasts had been widely publicized, asked Rossby to forecast the weather between Washington and Mexico City for December 13-14. After successfully completing the flight, Lindbergh called Rossby's the best weather forecast he had ever received. So incensed was Marvin by this unauthorized forecast that Rossby was told he was no longer welcome at the Weather Bureau.

But Lindbergh's flights and his unprecedented Guggenheim tour had awakened public interest in traveling by airplane, and now Harry Guggenheim had bigger plans for Rossby. To show the public that flying in airplanes was not just for daredevils anymore, the Guggenheim fund was financing the operation of a model airway service in California, to run between San Francisco and Los Angeles. Run by Western Air Express along its existing airmail routes, the model San Francisco-Los Angeles passenger service needed to prove to an uncertain American public that air travel was safe and reliable. This would require the best weather forecasting service possible. Rossby was asked to develop a model weather service to support this first regular airline passenger service in the United States, which would open for business in the spring of 1928.

It was Rossby's first major organizing effort, and he plunged in with characteristic zeal and flair for leadership. He walked into the San Francisco Weather Bureau office soon after the local official in charge, Major Edward H. Bowie, had received a letter from Marvin warning that Rossby was not to be accorded any special services or access to the offices of the agency. A wiser and more forward-thinking man, Bowie disregarded the letter and welcomed Rossby to California. With Western Air Express pilots, Rossby flew up and down the Central Valley, landing outside small towns with much fanfare, dining with mayors and local businessmen, and gaining their help in securing the most reliable local observers, who would report to the weather collection center at the Oakland Airport. Unlike the

Weather Bureau's simple arrangement, Rossby created a dense and broadly arrayed observation network, recognizing that bad flying weather was likely to sidle in from surrounding mountains rather than along the north-south axis of the route. Joining the 29-year-old Rossby in this project was Horace Byers, a young University of California student, who would become a protégé and a valuable managerial assistant. The weather service proved successful beyond all expectations, and the model airway marked the beginning of the age of passenger air travel in the United States. Not a single airplane accident was caused by weather during the experimental year. The model weather forecasting service won rave reviews from military as well as civilian pilots in California. Recognizing the inevitable, the U.S. Weather Bureau agreed to officially take over the service on July 1, 1929, and eventually extended it across the nation.

Carl Rossby, meanwhile, had already moved on to an enterprise that would establish his credentials, at the age of 30, as a leading figure in American meteorology. Guggenheim had funded the creation of a department of aeronautical engineering at the Massachusetts Institute of Technology. In 1928, Rossby was named associate professor of meteorology at MIT, with responsibility for organizing and implementing the first complete academic program in weather science at an American university. Over Marvin's objections at the Weather Bureau, Rossby enlisted for his faculty young Hurd Willett, who was freshly returned from a year's study in Bergen. The first year of instruction drew Reichelderfer's naval officers, and the second year began attracting civilian students, including Horace Byers from California, who was the first civilian to receive a doctorate in the program. Here Rossby met Harriet Alexander, of Boston, and the couple were married at the beginning of his second year at MIT.

"At MIT Rossby exhibited that leadership for which he was famous," Byers would later write. "Those who studied under him practically worshipped him. They were participating in his great crusade—to bring modern meteorology to America where the science had been existing in a stifling atmosphere for many years." Byers described the experience as exhilarating: "His lectures were carefully prepared and given with enthusiasm and his informal discussions . . . were nothing less than an inspiration."

Rossby would remain at MIT for 11 years, longer than anywhere else, and during that time he would singularly transform American meteorology from a wasteland into a leading international center of the science. Like Vilhelm Bjerknes's "living scientific milieu" in Bergen, Rossby's department of meteorology was noted for its informality, the freewheeling intensity of its scientific discussions, the stellar international talent it attracted as visiting faculty, and the close link it maintained between meteorological theory and the practice of weather forecasting. With a changing of the guard at the Weather Bureau, MIT's meteorology department would educate key new personnel. Like Bergen, the daily map discussion was a centerpiece of Rossby's academic program at MIT. Always the discussion led from the theoretical to the practical. "The proof of the pudding," he would say, "lies in eating it."

Meteorological history of another kind was made at MIT. In the midst of far-flung organizing work, which engaged him now everywhere he went, Carl Rossby presented results from his own research that established his reputation internationally as a theorist of atmospheric sciences second to none. In 1937, Jacob Bjerknes had published a paper that identified the formation of cyclones with hemisphere-scale upper-level waves. Extending this thought in 1939 and 1940, Rossby went much further, reaching what meteorologist George P. Cressman would describe as "a stunning conclusion." The upper-air waves extend vertically through the lower atmosphere, Rossby said, and the movement of the waves—which cause the movement of warm and cold air masses that produce local weather—is powered by the distribution of the forces derived from Earth's rotation. Rossby's famous equation accounts for this rotational energy, known as vorticity, because air currents as well as ocean currents flow from one latitude to another. In August 1939, in a paper presented in Toronto titled "Planetary Flow Patterns in the Atmosphere," Rossby concluded that "the factors determining the stationary or progressive character of the motion are to be found in the vorticity distribution and that the displacement of the pressure field is a secondary effect." In a 1996 interview, in the World Meteorological Organization Bulletin, Cressman called this contribution by Rossby "the key to the coming revolution in dynamic meteorology and in forecasting. The question that was to occupy us in the future was at hand; namely, to understand the full significance of Rossby's conclusion."

The effect of this rotational force creates a pattern of four to six large-scale "planetary waves" around the hemisphere that define the pattern of high-level westerly winds that encircle the pole and mark the boundary between polar air and warmer tropical air. These semipermanent waves, as well as their ridges and troughs, which would become such familiar features of modern weather maps, came to be known as Rossby waves, and are found in ocean basins as well as the atmosphere. Employing his famous talent for ruthlessly simplifying complex problems, Rossby went on to devise a mathematical formula that allows theorists and forecasters to calculate the movement of these waves—and the weather they carry—around the hemisphere. Extended five-day forecasts were first made possible by the use of this Rossby equation, which, according to science historian Gisela Kutzbach, "became perhaps the most celebrated analytic solution of a dynamic equation in meteorological literature."

In 1939, Rossby was naturalized as a U.S. citizen. Also that year, Reichelderfer was appointed chief of the U.S. Weather Bureau, with a mission and a mandate to modernize the nation's weather service. Five years earlier, a special scientific panel appointed by President Franklin D. Roosevelt had urged the agency to adopt the Norwegian air-mass analysis, but even this high-profile admonishment had not changed daily forecasting practices. Chief Marvin finally had resigned, and since 1935 Horace Byers and a few other MIT graduates had been at the agency, trying to initiate Bergen school forecasting methods. Meteorologist Jerome Namais recalled the continuing resistance to Byers's efforts. "His group was placed in a corner of the Weather Bureau—a safe distance from the forecasters," Namais wrote. "The forecasters were doing 'the real thing' and could not be contaminated by the young upstarts analyzing strangely in the other room." Real change did not come until Reichelderfer, the first outsider to head the agency in nearly 50 years, was put in charge. At Reichelderfer's urging in 1939, Rossby reluctantly agreed to leave MIT and temporarily accept the position of assistant chief for research and development of the U.S. Weather Bureau. Twenty years after Jacob Bjerknes's seminal paper on the subject, the irresistible forces of Reichelderfer's determination and Rossby's persuasive skills finally overcame the institutional resistance of the U.S. Weather Bureau to new scientific methods. In Washington, Rossby helped put a major reeducation program in place while Byers went off to Chicago to lead one of the regional training centers. But Rossby was not interested in government work, and in 1941 he left to become chairman of a new meteorology program at the University of Chicago, where Byers became an associate professor and Rossby's strong administrative hand—an arrangement which lasted for years.

More urgent matters would intervene, however. War had begun in Europe. The Nazis had invaded Norway in April 1940, stranding Jacob Bjerknes in the United States, and the likelihood of U.S. involvement in a second world war was growing each day. Carl Rossby was among the first to realize that this war would involve enormous airpower as well as weapons of mass destruction that would require battlefield weather forecasting. In 1940, even as public political dialogue focused on staying out of war, the U.S. government organized a massive training program for military meteorologists. It was Rossby's powers of persuasion that led military leaders, against their inclination, to employ civilian universities in the training of wartime weather forecasters. More than 7,000 servicemen underwent emergency training in meteorology at MIT, New York University, the University of Chicago, UCLA (where Bjerknes had established a department), and Caltech, as well as key military centers. The war years found Rossby traveling to every part of the world, helping local British and American military forecasters deal with special problems they encountered in unfamiliar skies. When military meteorologists realized that they knew too little about the Tropics to be effective in that theater, Rossby helped organize the University of Chicago's Institute of Tropical Meteorology in Puerto Rico.

The postwar years brought a flowering of scientific advances under Rossby at the University of Chicago, representing a leap of progress that probably was equal in importance to the Bergen school breakthroughs of the 1920s. Rossby's long-wave formula had crossed the divide from synoptic analysis of regional features to the kind of planetary dynamics that Vilhelm Bjerknes described when he dreamed of making meteorology an exact science in 1904. In the late 1940s in Chicago, one protégé after another plowed the ground that would lead to Numerical Weather Prediction by electronic computer, the triumph of weather science in the twentieth century. Byers was at his side, tending to administration, a role that cost him a certain amount of scientific recognition in his own right. The meteorologist H. Robert Simpson, an alumnus of that time, later would describe Byers as "the balance wheel in the administration of one of the great test meteorology programs the world has ever known; a spirited, if at times unruly, department energized in its early days by the creative genius of Carl Rossby." At the University of Chicago, Rossby was at his theoretical and inspirational best, building another remarkable academic research program around dynamic concepts. In an echo of Bergen, the program became known as the Chicago school, or the Rossby school, of meteorology.

What meteorologists think of as the famous "dishpan" experiments began in Chicago when Rossby encouraged graduate student Dave Fultz to "explore turbulent mixing using the hemispheric shell." Large round pans set on turntables were filled with water, chilled at their centers, and heated at their edges; their carefully controlled rotation proved remarkably effective at simulating the general circulation of the atmosphere. In Chicago after the war, the visiting Finnish meteorologist Erik Palmen, Rossby, and others defined the jetstream, a meandering current of highspeed winds embedded in the high-level westerly winds that had surprised

American bomber pilots crossing the Pacific during the war. Rossby and his collaborators—students and faculty, Americans and numerous international visitors—laid the theoretical framework for the numerical simulation of a simplified atmosphere that proved to be critical to the success of Numerical Weather Prediction by electronic computer in the 1950s. It was Rossby and friends who encouraged the great mathematician John von Neumann to take on the problem of Numerical Weather Prediction as one of the first major tasks for his new electronic computer. In 1947, however, just as that project was beginning to come to fruition at the Institute for Advanced Study in Princeton, New Jersey, Rossby surprised and disappointed many of his American colleagues and protégés by accepting the urgings of his native nation and returning to Sweden.

It was time to go. Nobody ever understood quite why. Carl Rossby was at the top of his powers scientifically and intellectually at the time. Perhaps he thought the return to Sweden would allow him to slow his hectic pace. He always felt that moving on to new domains and fresh challenges was vital to his personal development. Again during this time he surprised colleagues by taking up an entirely new set of scientific questions involving atmospheric chemistry and its effects on climate and weather. In this regard, Rossby was among the first meteorologists to recognize the potential harm of the continued industrial pollution of the atmosphere. Appearing on the cover of Time magazine in 1956, Rossby expressed misgivings about the buildup of various airborne substances, and noted that the atmosphere is "man's milieu" and that his well-being is linked so intimately to it. "Tampering can be dangerous," he warned. "Nature can be vengeful."

On August 19, 1957, Carl-Gustaf Rossby died suddenly in his office of a heart attack. He was 58 years old and at the top of his international fame and influence. The loss was personally staggering to the hundreds of meteorologists he had inspired around the world—none more so than to young Jule Charney, the brilliant theorist who was implementing Numerical Weather Prediction at the Institute for Advanced Study. Returning from Stockholm, he met a fellow meteorologist at a Paris airport and told him the awful news. "Without Rossby," Charney said, "my world has become dim."

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