A Numerical Model-derived Boundary Layer Turbulence Product

Abstract

A suite of numerical model-derived turbulence assessment products has recently been developed by NESDIS/STAR and implemented on the World Wide Web. The existing product suite is intended to provide turbulence information to aircraft flying in the vicinity of the jet stream. Turbulence is also a frequently occurring phenomenon in the boundary layer and may pose a threat to low-flying aircraft and aircraft during the take-off and landing phases of flight. Therefore, a numerical model-derived boundary layer turbulence product is under development. The boundary layer turbulence index (TIBL) product is designed to assess the potential for turbulence in the lower troposphere, generated using National Center for Environmental Prediction (NCEP) Rapid Update Cycle (RUC)-2 model data. The index algorithm approximates boundary layer turbulent kinetic energy (TKE) by parameterizing vertical wind shear, responsible for mechanical production, and kinematic heat flux, responsible for buoyant production. The TIBL product is expected to be most effective during the afternoon hours in a regime characterized by a quasi-steady state convective mixed layer. Preliminary case studies and validation have revealed a strong correlation between the presence of TKE maxima and peak wind gust magnitude observed at the surface in evolving morning or mature afternoon mixed layers.