50TH ANNIVERSARY OF OPERATIONAL NUMERICAL WEATHER PREDICTION BY KRISTINE HARPER, LOUIS W. UCCELLINI, EUGENIA KALNAY, KENNETH CAREY, AND LAUREN MORONE Editorial Note: A Meeting to Remember. The past examined the state of the art, and discussed the future few years have marked several important anniversaries of numerical weather prediction. For more details, the of landmark events in the history of numerical weather symposium agenda, a compilation of many of the most prediction (NWP). This past August was the 60th anni- important historic NWP papers (available as a CD-ROM), versary of the founding of the Meteorology Project at the and PowerPoint presentations are available online at www. Institute for Advanced Study in Princeton, New Jersey, the ncep.noaa.gov/nwp50. This essay was inspired by the major progenitor of modern weather prediction modeling. Simi- themes of that meeting. larly, 2004 was the 50th anniversary year of operational numerical weather prediction. To celebrate that anniver- he Joint Numerical Weather Prediction Unit (JN- sary and the vast changes NWP has spawned in weather WPU), a financial, administrative, and personnel forecasting, the National Centers for Environmental Pre- Tcollaboration of the U.S. Weather Bureau, Navy, diction (NCEP), the Air Force Weather Agency (AFWA), and Air Force, opened its doors on 1 July 1954. The the Fleet Numerical Meteorology and Oceanography operational unit was the culmination of research by Center (FNMOC), the National Weather Association, and the Meteorology Project at the Institute for Advanced the American Meteorological Society (AMS) cosponsored Study in Princeton, New Jersey; the Numerical Pre- the "Symposium on the 50th Anniversary of Operational diction Project at the Air Force Cambridge Research Numerical Weather Prediction," held on 14-17 June 2004 Laboratory's Geophysical Research Directorate; and at the University of Maryland in College Park, Maryland. the International Meteorological Institute in Stock- For three full days, participants shared their recollections, holm, Sweden. Directed by George Cressman, the JNWPU issued its first operational forecast on 6 May 1955—the day of its dedication. Operational numeri- AFFILIATIONS: HARPER—Department of Humanities, New cal weather prediction had stirred to life only a few Mexico Institute of Mining and Technology, Socorro, New Mexico; months earlier, in late September 1954, when Carl- UCCELLINI AND MORONE—National Centers for Environmental Pre- Gustav Rossby's Stockholm-based team produced diction, Washington, D.C.; KALNAY—Department of Atmospheric the first real-time barotropic forecasts on the Binary and Oceanic Sciences, University of Maryland, College Park, Electronic Sequence Calculator (BESK). Maryland; CAREY—Noblis, Inc., Falls Church, Virginia The JNWPU's first operational forecast maps were CORRESPONDING AUTHOR: Lauren Morone, National Cen- 36-h 400-, 700-, and 900-mb prognoses. The forecast ters for Environmental Prediction, 5200 Auth Road, Room 101, Camp Springs, MD 20746 charts were meteorological in nature and surpassed E-mail: [email protected] expectations, but did not include sensible weather elements and were far from good enough to replace DO!: 10.1175/BAMS-88-5-639 subjective human-based forecasts. However, the opera- In final form 5 December 2006 tional efforts on both sides of the Atlantic provided the ©2007 American Meteorological Society means for operational forecasters, theoreticians, and AMERICAN METEOROLOGICAL SOCIETY MAY 2007 BAFLS- | 639 Unauthenticated | Downloaded 10/09/21 06:55 AM UTC greatest intellectual achievement and scientific advancement in twentieth- century atmospheric science. Like most advances in the atmospheric sciences, NWP was an international achievement dependent upon close cooperation among all facets of the meteorology community—academic and governmental, theoretical and applied, research and operational, and military and civilian. Meteorology's successful research and operational attack on NWP depended on exploit- ing conditions produced by the spoils of World War II: the availability of vast amounts of surface and upper-air data, a 20-fold increase in meteorolo- Fred Shuman (left) and Otha Fuller circa 1955 at the IBM 701. The 701 gists, and the introduction of the new was the first computer used by the JNWPU to produce operational electronic digital computer. numerical weather prediction. Atmospheric scientists continued to exploit advances in all of these atmospheric modelers to combine forces to push NWP areas throughout the remainder of the century. from the fringes of theoretical and applied meteorology Data sources increased with the development of to mainstream atmospheric science within a decade. remote sensing. High-speed communication links Although far from obvious at the time, real-time delivered observational information quickly. Com- numerical weather prediction is now seen as the puter designers created and produced machines with more memory and faster processing capabilities. Moreover, some of the brightest minds in the world, fascinated with atmospheric processes, pursued REFLECTIONS ON THE EARLY DAYS advanced degrees in newly established academic OF OPERATIONAL NUMERICAL programs. The interplay between technological advancement, intradisciplinary cooperation, and WEATHER PREDICTION educational opportunities, coupled with a determi- nation to understand the Earth-atmosphere system he 50th Anniversary Symposium was a special occasion for and apply that knowledge for the benefit of both sci- T a number of reasons, not least because it gathered a num- ence and society, has been the driving force behind ber of the pioneers of numerical weather prediction. Several numerical weather prediction. We see this same of them shared their thoughts about the leading personali- force at work as the twenty-first century unfolds, ties and principal concerns of the early days of computers in creating great promise for the future of numerical forecasting. We quote from their presentations: weather prediction. ON RICHARDSON THE CONVERGENCE OF POLITICAL, SO- Bo Doos: It was a remarkable piece of work. Neverthe- CIAL, AND SCIENTIFIC DEVELOPMENTS. less, I do not think his contribution had very much of an The wide range of weather and climate models— impact on operational NWP. He was too far ahead of both research and operational—available today are his contemporaries in his vision of what might be pos- a direct result of efforts made by a dedicated group sible. There was no Lorenz in these days to inform him of meteorologists, mathematicians, programmers, that it is not always true that the more equations you and forecasters who entertained the notion that add to describe a system, the more accurate will be the objective techniques held the key to advancing the eventual forecast. atmospheric sciences. The NWP pioneers of the 1950s and those who followed in their wake during GEORGE PLATZMANN: At the time operational NWP the second half of the twentieth century did not just was being developed, in the mid-1950s, I believe » miraculously appear. They were the outgrowth of 640 I BAI15- MAY 2007 Unauthenticated | Downloaded 10/09/21 06:55 AM UTC A 1000-mb prog from grid- point "contouring" program written by Air Force Lt. Col. Art Bedient. Early model reso- lution was determined by the characters that could be print- ed per inch by the JNWPU's computer printers. A "bedi- ent" was set as the geographic distance between NWP grid points of one-half-inch separa- tion on a polar stereographic map projection true at 60° with a 1/30,000,000 scale. The resolution of the first NWP models were set at one bedient (381 km). Future models had resolutions set at lA bedient and VA bedient. political and social events, scientific and academic ef- forts within government laboratories and university departments, and technological developments in support than in past conflicts. Pilots needed weather computer and communication systems. Despite support, and they greatly increased the amount of the theoretical work of the nineteenth century, upper-air data available to forecasters. Observational early twentieth-century weather prediction was still more art than science. Its practitioners were often looked down upon by their mathematically rigorous scientific brethren. One scientist who de- Richardson's contributions were viewed mainly in cided to provide a mathematical and physical basis terms of his failed multilevel primitive-equation for meteorology was Norwegian physicist Vilhelm model. Paradoxically, his approach may have been Bjerknes. His participation in this endeavor was a more influential than at first sight appears, because product of broader trends. As historian of science it provided both a goal to strive toward and a lesson Robert Marc Friedman argued in his book on the in how not to begin. I should add that although Rich- Bergen School, Appropriating the Weather, Bjerknes ardson came to understand the underlying reason applied his circulation theorem to the atmosphere for his failure, it took about 25 years for a simple and oceans because there was no funding for his remedy to appear, the barotropic vorticity equation, theoretical physics field in Norway. Having com- which if I'm not mistaken, was the starting point for mitted himself to a new career path, Bjerknes fo- operational prediction. cused on applying physical principles that could be solved with mathematical techniques and argued ON ROSSBY that meteorologists needed to calculate the weather. Bo Doos: Rossby had