Studies of the Atmospheric Boundary Layer Using Numerical Simulations Coupled With Radar/Sodar-Based Field Observations

University Of Oklahoma Norman Campus, Norman OK

Investigators

Abstract

This project will provide a more comprehensive description of the structure, characteristics, and development of the stable boundary layer (SBL) and transitional atmospheric boundary layer (ABL). Both conceptual and computational challenges inherent in the proper representation of SBL conditions will be confronted. Researchers will use a combination of large-eddy simulation (LES) computer models, virtual and real wind profilers, and virtual and real sodars. Specific foci will include the transition from nighttime to daytime boundary layer conditions, generation of turbulence near the surface, and formation/development of low-level jets. The modeling and observational tasks will encompass (1) modifying an existing LES code to include the appropriate subgrid closure schemes to simulate stably stratified SBL conditions and transitional (morning and evening) regimes in the ABL; (2) developing a virtual sodar capable of probing the output fields of the LES and generating realistic data streams suitable for algorithm development and testing relevant to actual sodar operations; (3) integrating data from LES and targeted radar/sodar observations in order to systematically study and characterize stable boundary layer flows and the transition to other ABL regimes; and (4) using data from in-situ sensors, a radar wind profiler, and a sodar to further adapt the LES code for SBL and transitional ABL cases and validate performance of the virtual sodar. The intellectual merit of this effort lies in the improvement of simulations of the stably stratified boundary layer and transitional flow regimes, which are not as mature as simulations of the convective boundary layer (CBL). Complementary wind profiler and sodar measurements make it possible to comprehensively capture the development of the boundary layer, and when combined with LES modeling will provide a unique opportunity to investigate the effectiveness and applicability of both LES and other means of characterizing the CBL, SBL and transitions between the two. The broader impacts of this work include the education and training of graduate and undergraduate students, including a connection to an existing Research Experience for Undergraduates (REU-Site) program at the University of Oklahoma, with emphasis on student exposure to modern instrumentation. Improved techniques for observing and simulating atmospheric conditions in the lowest layers of the atmosphere will potentially benefit user communities in agriculture, civil and commercial aviation, and renewable energy generation. Enhanced exchange between scientific (e.g., meteorological) and engineering (e.g., instrument design) disciplines will be promoted.