A Terminal Area PBL Prediction System at Dallas–Fort Worth and Its Application in Simulating Diurnal PBL Jets

Abstract

A state-of-the-science meso-b-scale numerical weather prediction model is being employed in a prototype forecast system for potential operational use at the Dallas-Fort Worth International Airport (DFW). The numerical model is part of a unique operational forecasting system being developed to support the National Aeronautics and Space Administration's (NASA) Terminal Area Productivity Program. This operational forecasting system will focus on mesob-scale aviation weather problems involving planetary boundary layer (PBL) turbulence, and is named the Terminal Area PBL Prediction System (TAPPS). TAPPS (version 1) is being tested and developed for NASA in an effort to improve 1-6-h terminal area forecasts of wind, vertical wind shear, temperature, and turbulence within both stable and convective PBLs at major airport terminal areas. This is being done to enhance terminal area productivity, that is, aircraft arrival and departure throughput, by using the weather forecasts as part of the Aircraft Vortex Spacing System (AVOSS). AVOSS is dependent upon nowcasts or short-period forecasts of wind, temperature, and eddy dissipation rate so that the drift and dissipation of wake vortices can be anticipated for safe airport operation. This AVOSS system will be demonstrated during calendar year 2000 at DFW. This paper describes the numerical modeling system, which has three basic components: the numerical model, the initial data stream, and the postprocessing system. Also included are the results of several case study simulations with the numerical model from a field program that occurred in September 1997 at DFW. During this field program, detailed local measurements throughout the troposphere, with special emphasis on the PBL, were taken at and surrounding DFW in an effort to verify the numerical model simulations. Comparisons indicate that the numerical model is capable of an accurate simulation of the vertical wind shear structure during the diurnal evolution of the PBL when compared directly to specific local observations. The case studies represent unambiguous examples of the dynamics of the Great Plains diurnal low-level jet stream. This diurnal jet stream represents the dominant low-level wind shear-production mechanism during quiescent synoptic-scale flow regimes. Five consecutive daily case studies, during which this phenomenon was observed over and in proximity to DFW, are compared to the products derived from TAPPS.

Climatology of the Low-Level Jet at the Southern Great Plains Atmospheric Boundary Layer Experiments Site

“…Kaplan et al (2000) presented both observations and numerical model results indicating the structure of the LLJ in Dallas-Fort Worth, Texas. Berbery and Rasmusson (1999) further suggested that understanding how jet behavior is influenced by largescale flow patterns should help to reveal the role of large-scale climate variations in regulating regionaland continental-scale water budgets.…”

The diurnal cycle of lower boundary‐layer wind in the West African monsoon

“…This example also corresponds to a mean wind shear of around 5-6 m s −1 (100 m) −1 , assuming low surface wind speed. Similarly, in five casestudies from Dallas-Fort Worth International Airport, Kaplan et al (2000) showed that the average peak wind shear below the nocturnal jet was 2.9 m s −1 (100 m) −1 .…”

Characterizing the severe turbulence environments associated with commercial aviation accidents. A real-time turbulence model (RTTM) designed for the operational prediction of hazardous aviation turbulence environments

“…The numerical model is MASS version 5.13 (Kaplan et al 2000). The MASS model is a hydrostatic terrain-following sigma coordinate system with comprehensive boundary layer and convective parameterizations (note table 1).…”