Boundary Layer Structure and Evolution During Terrain-induced Rotor EXperiment (T-REX)

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The Principal Investigator (PI) will study the evolution of the first few km of the lower atmosphere during the Terrain-Induced Rotor Experiment (T-REX). The T-REX is a multi-investigator focused on the study of mountain rotors and other lee wave phenomena. In his research, the PI will use state-of-the-art high-resolution Doppler lidar and high-resolution profiles of velocity, temperature, turbulence, ozone, and aerosol particle concentration. The PI also will deploy a Tethered Lifting System (TLS). The focus of this effort is the evolution of small-scale turbulence, wave-turbulence interactions, and variations of the boundary layer height and dynamics during the rotor events. In addition, new lidar algorithms will be modified to provide real-time profiles of turbulence and wind information to guide the deployment of field instruments, particularly aircraft and tethered systems, when conditions of high turbulence are present and pose a possible hazard. The Doppler lidar analyses will focus on extracting reliable small-scale turbulence information by correcting the effects of the spatial averaging by the lidar pulse volume. This development will permit more accurate comparisons between the lidar results and the in situ turbulence measurements provided by the TLS profiles. Comparable developments in the TLS technique will enable concurrent, high-resolution profiling of winds, temperatures, and turbulent properties from the surface to heights of a few km. A newly developed temperature sensor chain flown from the TLS will also be deployed to provide more accurate temperature gradients for measurements of thermal stability in the boundary layer. The primary focus of the in situ measurements will be the stable boundary layer (SBL) and the nighttime remnants of the daytime convective processes that define the residual layer (RL). Daytime conditions will also be considered depending on the logistical constraints of the field program and the importance of the daytime measurements for the various stages of the rotor evolution. The intellectual merit of the research includes an improved understanding of boundary layer processes from the unprecedented high-resolution in situ data and the three dimensional measurements of wind fields and turbulence with Doppler lidar. The simultaneous measurements will also provide the first validation of accurate turbulence estimates with an operational Doppler lidar as well as verification of new model derived estimates of small scale turbulence which are critical for next generation optimal data assimilation and numerical weather prediction models. The broader impacts include improved methods for model parameterization especially correct calculations of the boundary layer height, improved forecasts of terrain induced turbulence for aviation safety, and new input to optimal data assimilation for the challenging conditions of complex terrain and stable boundary layers. The value of real-time wind speed and turbulence profiles will be demonstrated to guide future field campaigns.