TTUKa radar update: Fronts, Virga, and outflow

The TTUKa radar team was able to collect coordinated dual-Doppler measurements over the BAO site yesterday evening. We targeted a weak cold front and subsequent light precipitation / virga that passed through the area just after 00 UTC on the 13^th.  There was just enough convergence of Ka scatterers to observe the near-surface structure of the frontal boundary (TTUKa2 reflectivity on the left and radial velocity on the right):

A few wind profiles of the frontal passage from virtual tower scanning may also be available (analysis pending). Persistent second trip echoes contaminated much of the pre- and post- environment until some light precip began falling behind the front. Virga was also observed and likely contributed to the higher wind speeds observed in the TTUKa radial velocity fields and dual-Doppler wind profiles. Below is an animation of 15 minutes of good radial velocity data (m/s) from the perspective of Ka2:

The location of the RHI intersection location is denoted by the vertical black line. The solid red line is the 30 m NED elevation.  These data have only been edited slightly, thus second trip echoes are still visible in some places. The wind profile (revist time of ~ 8.9 seconds on average) demonstrates substantial evolution through the time period, including several jet profiles that are reminiscent of outflow. The latter is not surprising given observed virga.  Based on a quick peak at the tower data from the BAO website, there was decent agreement between the tower wind speeds and the dual-Doppler speeds.  Interaction of the outflow winds with terrain features was also observed and perhaps some terrain speed up effects as well.

It should also be noted that only very light precip was noted at both the location of TTUKa1 and TTUKa2, so hopefully data from the lidars (and other instruments) will be able to be compared to the radar data. Also, the dual-Doppler intersection point was ~105 m from the lidar supersite and ~206 m to the southeast of the BAO tower. I do want to emphasize that these data are very preliminary and reflect only slight editing / quality control.

In all we collected approximately 2.5 hours of coordinated data yesterday evening.

The air mass in the wake of last night’s activity was not conducive to coordinated data collection despite performing multiple test scans to make sure. While data quality was not terrible, the low cu field did create second trip echo issues that could not be overcome in the low reflectivity environment. We used 39 minutes for test scans today which, combined with the data collection efforts yesterday brings us to 1324 minutes of 7200 total minutes.