TTUKa Radar update, deployment locations, and virtual tower issues

First things first, the coordinates (lat/lon/el) for the radars are also included below:

Ka1:  40.062100  / -105.037130 / 1548 m

Ka2:  40.080462 / -104.984199 / 1539 m

To recap the discussion on the conference call yesterday, initial analysis of the clear air dataset collected on 9 March 2015 revealed significant contamination of the bins above the lidar supersite by the guy wires. While we expect this effect to be substantially reduced during precipitation, it obviously presents a problem for clear air data collection (particularly virtual towers over the lidar supersite). To address this issue, the TTUKa radar team spent the better part of yesterday looking for a new deployment site for Ka1 such that RHI would not broad-side the guy wires. Despite multiple attempts, we were unsuccessful in finding a site that avoided the guy wires yet still satisfied dual-Doppler geometry with limited ground clutter. We did however, get a nice tour of Erie and the surrounding countryside….

We then decided not to alter the deployment of Ka1, but instead turn our attention to varying the RHI from Ka2 (the northern radar) so as to move the RHI intersection point away from the guy wires. This shift also unfortunately moves the virtual tower away from the lidar supersite. The dilemma now is how far to offset the virtual tower. With an offset of 56 m though ~ 102 m, there is still guy wire contamination in the profile. At 102 m onward, there is very little contamination. The profiles appear to be completely clean at ~150 m offset. In the first (second) image below, the shaded field is TTUKa1 calibrated reflectivity (thresholded radial velocity). The solid vertical black line is the current intersection point (of the RHI from TTUKa2) over the supersite. The three dashed vertical lines are the TTUKa2 intersection points for 50, 102, and 150 m offsets respectively. 

I understand the preference is to maintain the intersection point over (or as close to) the lidar supersite as possible. However it appears that for decently clutter-free, clear-air, profiles this will require and offset of ~102 m. Unless there is strong objection, we will use the 102 m offset for clear air profiles and 0 offset when conditions are appropriate (precip / high reflectivity). Feedback on this plan is welcome and appreciated. We will obviously take detailed notes as to when the offset is applied. 

The forecast calls for some light precip this evening into the overnight. The TTUKa radar team will plan to target an precip that many move through in addition to a test scan / possible clear air data collection this afternoon. After a test scan on Tuesday and substantial testing yesterday, we have currently used 980 of the available 7200 minutes.