Aviation Meteorology

by

John Knox, Nicholas J. Morgan, Emily M. Sullivan, Emily N. Wilson, David S. Nevius

• LAST REVIEWED: 29 November 2018
• LAST MODIFIED: 29 November 2018
• DOI: 10.1093/obo/9780199874002-0196

Introduction

Aviation meteorology is the study of weather from the unique perspective of the aviation industry. This subject began during the era of hot-air balloons and gliders. Notable early “aerologists” Léon Teisserenc de Bort of France and Robert Assmann of Germany are co-credited with the discovery of the stratosphere in 1902 via independent, multiple high-altitude balloon ascents. Across the Atlantic, aerologist Clarence LeRoy Meisinger received one of the early doctorates in the United States in meteorology in 1922, but he perished in a balloon accident during a thunderstorm just two years later. The surge in heavier-than-air powered flight during the two world wars led to the professionalization of aviation meteorology. Subjects such as high-level or “clear-air” turbulence materialized as aircraft regularly penetrated largely unexplored regions of the atmosphere. The rise of commercial aviation after World War II led to the development of private-sector aviation meteorology groups within individual airlines. Much of the development of modern aviation meteorology took place within these groups and in conjunction with government agencies, rather than in academic settings. Despite the later consolidation or elimination of many airline meteorology groups, aviation meteorology remains an unusually practical and applied specialty. As a result, a newcomer to aviation meteorology from an academic background may be surprised at the relative lack of scholarly material compared to other subjects. Another surprise may be the distinctively empirical approach to forecast problems that still remains—although the latter has lessened in recent decades via contributions from research scientists. One enduring challenge for aviation forecasting has been that advances in prediction are often reliant on aircraft encounters with aviation hazards such as turbulence, wind shear, icing, and volcanic ash. A more desirable outcome for pilots, passengers, and airlines would be the avoidance of these hazards. As aviation forecasting has improved such encounters have decreased, which can have an ironic diminishing returns effect on forecast improvements. This limitation can be overcome to some extent by theoretical and modeling advances. The relatively new field of space weather also intersects with aviation meteorology because of the impact that an active Sun can have on aviation communication and navigation, as well as human health. Beyond the focus on forecasting for commercial aviation, environmental impacts due to contrails and climate change have been a part of aviation meteorology for several decades as well. Despite its empirical roots, aviation meteorology should not be viewed as a less worthy subject for academic study. The practical demands of aviation safety intersect with some of the most complicated phenomena and most vexing forecast problems in the entire field of meteorology, on scales that are still not resolvable by the world’s best weather forecasting models. Study of aviation meteorology is rewarding: in terms both of saving lives and of reducing injuries and as a scientific pursuit in its own right.

Aviation Meteorological Observations

Aviation meteorology is critically dependent on observations for both avoidance and forecasting. Surface-based observing systems, such as weather radar, provide information on the location and severity of convection, as explained in Serafin and Wilson 2000, with a more recent update in Baldini, et al. 2018. Airborne weather radar has limitations that can be relevant for aircraft safety, as presented in Allen, et al. 1981. Evans and Turnbull 1989 describes the Terminal Doppler Weather Radar and its effectiveness in identifying low-altitude wind shear events associated with microbursts that caused many deadly aviation accidents in the 1970s and 1980s. Automated airborne weather observations are surveyed in Moninger, et al. 2003, including ACARS/AMDAR data that have become an important component of observational data for today’s numerical weather prediction models. One derived quantity of automated airborne weather data that is particularly relevant for aviation turbulence, eddy dissipation rate, is explained in Cornman, et al. 2004, a highly cited conference preprint. Non-automated airborne weather observations, in the form of pilot reports, continue to provide important information. Schwartz 1996 points out the flaws in using this data for research purposes, and Casner 2010 examines why these reports are not made more often.

• Allen, R. H., D. W. Burgess, and R. J. Donaldson Jr. “Attenuation Problems Associated with a 5 cm Radar.” Bulletin of the American Meteorological Society 62.6 (1981): 807–810.

  DOI: 10.1175/1520-0477-62.6.807

  This short article illustrates the weakening of return signal from radars with wavelength less than the 10 cm standard for ground-based radars. This research followed on the heels of the April 1977 Southern Airways crash in which the pilot attempted to penetrate a squall line at a weak point, which turned out instead to be the strongest part of the line. Available online.

• Baldini, L., N. Roberto, M. Montopoli, and E. Adirosi. “Ground-Based Weather Radar to Investigate Thunderstorms.” In Remote Sensing of Clouds and Precipitation. Springer Remote Sensing/Photogrammetry. Edited by C. Andronache, 113–136. Cham, Switzerland: Springer, 2018..

  DOI: 10.1007/978-3-319-72583-3_4

  This article provides an up-to-date summary of weather radar, including dual-polarization and dual Doppler methods, with specific reference to their use in the detection of signatures of convection. Available online for purchase.

• Casner, S. M. “Why Don’t Pilots Submit More Pilot Weather Reports (PIREPs)?” International Journal of Aviation Psychology 20.4 (2010): 347–372.

  DOI: 10.1080/10508414.2010.487015

  One problem with the use of pilot reports (PIREPs) for research purposes is the lack of coverage, especially “null” reports. In this article, Casner surveys 189 general aviation pilots to learn more about what barriers prevent more frequent reporting—a key barrier being a sense that reports should be made only during adverse weather. The article also includes a “climatology” of PIREPs for 2003–2008 by aircraft type and weather phenomenon reported. Available online for purchase.

• Cornman, L. B., G. Meymaris, and M. Limber. “An Up[d]ate on the FAA Aviation Weather Research Program’s In Situ Turbulence Measurement and Reporting System.” Preprints, 11th Conference on Aviation, Range, and Aerospace Meteorology, Hyannis, MA, 4–8 October 2004. Boston: American Meteorological Society, 2004.

  This is a widely cited conference preprint summarizing the details of calculating the eddy dissipation rate, or EDR, from accelerometers on large-body commercial aircraft. EDR is becoming the standard measure of “truth” for turbulence observations, supplanting the more error-prone pilot reports.

• Evans, J., and D. Turnbull. “Development of an Automated Windshear Detection System Using Doppler Weather Radar.” Proceedings of the IEEE 77.11 (1989): 1661–1673.

  DOI: 10.1109/5.47729

  This article provides the context and early history of Terminal Doppler Weather Radar (TWDR), including explanations of the meteorology behind the microbursts that led to its creation and the design specifications for the radar itself. The algorithms for detection of low-level wind shear events are summarized, as is the performance of the detection system. Available online for purchase or subscription.

• Moninger, W. M., R. D. Mamrosh, and P. M. Pauley. “Automated Meteorological Reports from Commercial Aircraft.” Bulletin of the American Meteorological Society 84.2 (2003): 203–216.

  DOI: 10.1175/BAMS-84-2-203

  This article provides a turn-of-the-21st-century overview of the history and advances in automated airborne reports, focusing on ACARS/AMDAR data across the United States and worldwide. While the embedded Internet links no longer work, this article provides a good introduction to the more general subject of automated weather observations from aircraft. Available online.

• Schwartz, B. “The Quantitative Use of PIREPs in Developing Aviation Weather Guidance Products.” Weather and Forecasting 11.3 (1996): 372–384.

  DOI: 10.1175/1520-0434(1996)011<0372:tquopi>2.0.co;2

  In this paper, an analysis of pilot reports of turbulence (PIREPs) over the continental United States and Alaska is employed to show that the reports contained within the PIREPs database are inadequate for defining the actual phenomenology of aviation weather hazards. The magnitude of the errors in space, time, and intensity make PIREPs undesirable for use in research and even operations. Available online.

• Serafin, R. J., and J. W. Wilson. “Operational Weather Radar in the United States: Progress and Opportunity.” Bulletin of the American Meteorological Society 81.3 (2000): 501–518.

  DOI: 10.1175/1520-0477(2000)081<0501:OWRITU>2.3.CO;2

  This review of the NEXRAD weather radar system provides an overview of the advances of Doppler radar as well as some of its weaknesses. Section 3 gives a good summary of Terminal Doppler Weather Radar (TDWR) implementation and its successes in averting microburst-related aviation accidents. Available online.