A Study of High Temporal and Spatial Resolution RHIs Through Outflow Boundaries and Squall Lines Using the Atmospheric Imaging Radar

In this study, RHIs through quasi-linear structures are examined using the Atmospheric Imaging Radar (AIR), an X-band radar designed by the University of Oklahoma's Advanced Radar Research Center (ARRC). The AIR transmits a vertical 20-degree fan beam, allowing for digital beamforming on receive to capture a nearly instantaneous vertical snapshot of the atmosphere. With a PRT of 714 microseconds, this allows for Range-Height Indicator (RHI) updates with acceptable data quality as quickly as every 350 milliseconds. Pulse compression techniques allow for 30-meter range resolution, and digital beamforming results in 1 degree vertical resolution, oversampled to 0.5 degrees. In contrast to traditional ‘pencil-beam' radars, the AIR allows for simultaneous RHIs, such that any changes from one RHI to another are not a side effect of differential vertical advection. This allows for AIR data to be analyzed on shorter time scales than what would be possible with NEXRAD and TDWR data. This study evaluates these quasi-linear structures at a significantly higher temporal and spatial resolution than what has previously been achieved, and identifies quickly evolving structures within the system. RHIs from outflow boundary and squall line cases, along with a thorough analysis of the RHI content, are discussed in this study.