Characterizing The Severe Turbulence Environments Associated With Commercial Aviation Accidents Part 2 Hydrostatic Mesobeta Scale Numerical Simulations Of Supergradient Wind Flow And Streamwise Ageostrophic Frontogenesis

Simulation experiments reveal key processes that organize a hydrostatic environment conducive to severe turbulence. The paradigm requires juxtaposition of the entrance region of a curved jet stream, which is highly subgeostrophic, with the entrance region of a straight jet stream, which is highly supergeostrophic. The wind and mass fields become misphased as the entrance regions converge resulting in the significant spatial variation of inertial forcing, centripetal forcing, and along- and cross-stream pressure gradient forcing over a mesobeta scale region. This results in frontogenesis and the along-stream divergence of cyclonic and convergence of cyclonic ageostrophic vertical vorticity. The centripetally forced mesoscale front becomes the locus of large gradients of ageostrophic vertical vorticity along an overturning isentrope. This region becomes favorable for streamwise vorticity gradient formation enhancing the environment for organization of horizontal vortex tubes in the presence of buoyant forcing.Kaplan, Michael L. and Huffman, Allan W. and Lux, Kevin M. and Cetola, Jeffrey D. and Charney, Joseph J. and Riordan, Allen J. and Lin, Yuh-Lang and Waight, Kenneth T., III and Proctor, Fred (Technical Monitor)Langley Research CenterSIMULATION; HYDROSTATICS; TURBULENCE; GEOSTROPHIC WIND; CIVIL AVIATION; COMMERCIAL AIRCRAFT; AIRCRAFT ACCIDENTS; JET STREAMS (METEOROLOGY); CENTRIPETAL FORCE; PRESSURE GRADIENTS; VORTICITY; FRONTS (METEOROLOGY)

A 44 case study analysis of the large-scale atmospheric structure associated with development of accident-producing aircraft turbulence is described. Categorization is a function of the accident location, altitude, time of year, time of day, and the turbulence category, which classifies disturbances. National Centers for Environmental Prediction Reanalyses data sets and satellite imagery are employed to dang- nose synoptic scale predictor fields associated with the large-scale environment preceding severe turbulence. These analyses indicate a predominance of severe accident-producing turbulence within the entrance region of ajet stream at the synoptic scale. Typically, a flow curvature region is just upstream within the jet entrance region, convection is within 100 krn of the accident, vertical motion is upward, absolute vorticity is low, vertical wind shear is increasing, and horizontal cold advection is substantial.

Anyone who has experienced turbulence in flight knows that it is usually not pleasant, and may wonder why this is so difficult to avoid. The book includes papers by various aviation turbulence researchers and provides background into the nature and causes of atmospheric turbulence that affect aircraft motion, and contains surveys of the latest techniques for remote and in situ sensing and forecasting of the turbulence phenomenon. It provides updates on the state-of-the-art research since earlier studies in the 1960s on clear-air turbulence, explains recent new understanding into turbulence generation by thunderstorms, and summarizes future challenges in turbulence prediction and avoidance.

This Topical Volume focuses on aviation meteorology for operations and research, covering important topics related to wind and turbulence, visibility, fog and precipitation, convection and lightning, icing, blowing snow, and ice cloud microphysics and dynamics. In addition to forecasting issues, the impact of climate on aviation operations is also highlighted, as temperature and moisture changes can affect aircraft aerodynamic conditions, such as lift and drag forces. This work uses measurements from state of art in-situ instruments and simulation results from numerical weather prediction (NWP) and climate models. New technologies related to satellites, radars, lidars, and UAVs (Unmanned Aerial Vehicles) are described, as well as new analysis methods related to artificial intelligence (AI) and neural network systems. Use of remote sensing platforms, including satellites, radars, radiometers, ceilometers, sodars, and lidars, as well as knowledge of the in-situ observations for the monitoring and short-term forecasting of wind, turbulence, gust, clear air turbulence (CAT), low visibility due to fog and clouds, and precipitation types are required for aviation operations at the airports and high level flying conditions. This book provides extensive knowledge for aviation-related meteorological processes and events that include short and long term prediction of high impact weather systems. Aviation experts, weather offices, pilots, university students, postgraduates, and researchers interested in aviation and meteorology, including new instruments for measurements applicable to forecasting and nowcasting, can benefit from consulting and reading this book. This book provides a comprehensive overview of our existing knowledge and the numerous remaining difficulties in predicting and measuring issues related to wind and turbulence, convection, fog and visibility, various cloud types, icing, and ice clouds at various time and space scales. Previously published in Pure and Applied Geophysics, Volume 176, Issue 5, 2019

Mesoscale weather systems are responsible for numerous natural disasters, such as damaging winds, blizzards and flash flooding. A fundamental understanding of the underlying dynamics involved in these weather systems is essential in forecasting their occurrence. This 2007 book provides a systematic approach to this subject. The opening chapters introduce the basic equations governing mesoscale weather systems and their approximations. The subsequent chapters cover four major areas of mesoscale dynamics: wave dynamics, moist convection, front dynamics and mesoscale modelling. This is an ideal book on the subject for researchers in meteorology and atmospheric science. With over 100 problems, and password-protected solutions available to instructors at www.cambridge.org/9780521808750, this book could also serve as a textbook for graduate students. Modelling projects, providing hands-on practice for building simple models of stratified fluid flow from a one-dimensional advection equation, are also described.

Proceedings of the NATO Advanced Study Institute "Decadal Climate Variability: Dynamics and Predictability", held at Les Houches, France, February 13-24, 199

A 44 case study analysis of the large-scale atmospheric structure associated with development of accident-producing aircraft turbulence is described. Categorization is a function of the accident location, altitude, time of year, time of day, and the turbulence category, which classifies disturbances. National Centers for Environmental Prediction Reanalyses data sets and satellite imagery are employed to dang- nose synoptic scale predictor fields associated with the large-scale environment preceding severe turbulence. These analyses indicate a predominance of severe accident-producing turbulence within the entrance region of ajet stream at the synoptic scale. Typically, a flow curvature region is just upstream within the jet entrance region, convection is within 100 krn of the accident, vertical motion is upward, absolute vorticity is low, vertical wind shear is increasing, and horizontal cold advection is substantial.