Numerical Modeling Studies of Multiple Aviation Turbulence Forecasting Problems in the Troposphere and Stratosphere

RINGLEY, CHAD J. Numerical Modeling Studies of Multiple Aviation Turbulence Forecasting Problems in the Troposphere and Stratosphere. (Under the direction of Profs. Yuh-Lang Lin and Michael Kaplan). This thesis is composed of papers derived from two separate projects designed to investigate important aspects and problems in turbulence evolution and forecasting in aviation meteorology. The first paper explores the validation of an updated numerical model configuration performed for the design of a comprehensive low-level wind climatology for boundary layer turbulence in conjunction with the National Aeronautics and Space Administration (NASA) Terminal Area Productivity Program (TAP). The second paper investigates turbulence generation and evolution with explicit turbulence diagnostics with both convective and orographic forcing in the upper troposphere and lower stratosphere in conjunction with the United States Air Force Research Laboratory. In the first paper, a new version of the Terminal Area PBL Prediction System (TAPPS-2) model is tested to simulate low-level winds, turbulent kinetic energy (TKE) and eddy dissipation rate (EDR) profiles in order to develop a statisticallybased wake vortex forecasting tool for air-traffic controllers. A series of TAPPS-2 simulations are validated against tower observations from the Aircraft Vortex Observing and Sampling System (AVOSS) at the Dallas-Fort Worth International Airport from the 17-20 September 1997 intense observing periods (IOPs). The TAPPS-2 system simulated the evolution of turbulence with respect to diurnal forcing and the ubiquitous diurnally-forced low-level jet during the validation period. The TAPPS-2 system also showed significant sensitivity to vertical resolution, model initialization time, and the formulation of the characteristic length scale of large eddies, and recommendations for the design of the low-level wind climatology are presented. In the second paper, the stratospheric version of the Non-Hydrostatic Mesoscale Atmospheric Simulation System (NHMASS) model is used to simulate and evaluate the development, maintenance, and evolution of turbulence in the upper troposphere and lower stratosphere where convective and terrain-induced aviation turbulence pose a significant threat to high-altitude flying aircraft operated by the United States Air Force. Using both a convective case (12 December 2002) and mountain wave case (9 December 1992), the NHMASS model’s 1.5 order PBLbased TKE scheme is compared against an explicit spatial and temporal Reynolds’ averaging technique used to derived explicit turbulence diagnostics. The Reynolds’averaging based TKE calculations, derived from explicit momentum and heat fluxes, reveals a much more detailed potential turbulence evolution as compared with the PBL-based TKE flux parameterizations. Explicit grid turbulence diagnostics are able to resolve small-amplitude gravity waves in the lower and middle stratosphere in the convective case when the mean wind shear and model TKE is low in the convective case and a shift in hydraulic jump within the PBL which is coincident with wave breaking in the lower stratosphere. The explicit grid based diagnostics are to be used in future automatic grid nesting algorithms at very fine horizontal grid spacing. Numerical Modeling Studies of Multiple Aviation Turbulence Forecasting Problems in the Troposphere and Stratosphere