CAREER: Towards Better Representations of the Nocturnal Low-Level Jets in New Generation Large-Eddy and Mesoscale Models

Texas Tech University, Lubbock TX

Investigators

Abstract

This work will focus on a closely coordinated observational and numerical study of wind structure in the lowest layers of the atmosphere, with particular attention to mechanisms leading to development of a recurring wind pattern known as the "low level jet" (as in jetstream, aka LLJ, which frequently develops during nighttime hours over the U.S. central plains during spring/summer months). Particular attention will be directed toward identifying environmental controls on the degree to which this elevated source of momentum (and hence energy) is mixed down toward the earth's surface and its subsequent impacts on renewable energy production via wind turbines. The investigator's approach will embody a combination of: (1) development of an expanded observational database describing LLJ structure via an array of existing facilities operated by Texas Tech (including a 200 m tower mounted with sonic anemometers at 10 discrete levels) in conjunction with a newly acquired scintillometer--all of which are key to better understanding near-surface wind profile evolution under LLJ conditions; (2) numerical simulations to quantify turbulent controls on the intermittent vertical mixing of momentum from the level of the LLJ down to that of wind turbines during stably-stratified conditions typical of nighttime; (3) development of a new graduate-level course at Texas Tech University entitled "Wind Power Meteorology"; and (4) a broad K-12 outreach effort exposing teachers and students at local schools to a variety of classroom and field activities that will significantly enhance both primary and secondary science education. A particularly novel aspect of this project is inclusion of the "Large Eddy Simulation" (LES) approach in tandem with more traditional mesoscale simulations conducted via the Weather Forecasting Model (WRF). This effort, in tandem with above-mentioned special observations, will better describe the occurrence (and ultimately serve to achieve more accurate prediction) of episodes of turbulence in which stronger winds rooted aloft in the core of the LLJ mix downward toward the surface. The Broader Impacts of this work are substantial, and will include more accurate forecasts of changes in urban air quality and power generation capacity across large networks of turbine-powered electric generators ("wind farms") whose implementation is expanding rapidly in this era of mounting petroleum prices. Considerable enhancements to education at primary, secondary and university level will also occur as students are exposed to various aspects of the observation and numerical forecast of near-surface winds through suitable data visualization techniques (in the classroom) and field trips to become more familiar with renewable energy generation systems.