Boundary Layer Structure and Low-Level Jets during PECAN

The Plains Elevated Convection at Night (PECAN) campaign was a large multi-agency project in the Great Plains region of the United States from June 1 to July 15, 2015. The project’s intensive observations focused on gaining a better understanding of nocturnal convection in the region and associated events such as low-level jets (LLJs). The research presented here will focus on boundary layer (BL) morning and evening transition periods, the interaction of these periods with LLJ development, and the impact of LLJs on the nocturnal stable layer. A comparison of BL heights during transition periods will be made between the Weather Research and Forecasting Model (WRF) and observations from surface and profiling instruments, including a novel Doppler lidar fuzzy logic algorithm for continuous mixed layer height monitoring. The timing of these transitions and the vertical structure of boundary layer turbulence will be considered for their influence on LLJ evolution. Between the transition periods we explore LLJ impacts on inversion strength and mixing within the stable layer. Improving understanding of BL transitions and LLJ interactions with the BL is important for weather forecasting and air quality, and contributes to the overarching PECAN research goals.