TTUKa XPIA Results: Data Validation and Boundary Layer Structure

As part of the DOE Atmospheres to electrons (A2e) initiative focused on providing a better understanding of wind farm complex flows, the eXperimental measurement campaign for Planetary boundary layer Instrument Assessment (XPIA) was carried out at the Boulder Atmospheric Observatory (BAO) in Spring 2015. The Texas Tech University Ka mobile Doppler radars (TTUKa) participated in XPIA from 4 March 2015 through 4 April 2015, collecting 17 dual-Doppler datasets in both precipitation and clear air environments. These datasets included wind profiles generated from long durations of "virtual tower" scanning as well as high-resolution 3-D volumes of dual-Doppler wind speed and direction centered over the BAO field site. Several of these datasets have been analyzed and compared with other platforms, including the six levels of sonic anemometers mounted on northwest and southeast corners of the BAO tower, profiling lidars located approximately 149 m south of the BAO, and scanning lidars collecting triple Doppler data at 100 m over a small portion of the domain. The TTUKa dual-Doppler data demonstrated excellent agreement (high correlation; low bias) with most platforms. In addition to the instrument comparison, analysis of the high and spatial resolution of the TTUKa dual-Doppler volumes revealed many different meso- and micro-scale boundary layer features including frontal passages, coherent linear wind speed streaks, large clear-air vortices, and a persistent wake from the BAO tower that propagated up to 1500 m downstream in some environments. The analysis of these features as well as their impact on the instrument comparison will be discussed.