BAO 28 Apr 2015
~1730-1800 UTC the T/RH was replaced at 300m. S boom was in (bad directions) and N boom may be off by 5- 15 degrees too.
NCAR reported all looks good now.
~,4" of precip with last system.

Data and quicklooks from the Halo Photonics Streamline lidar are available at


https://engineering.arm.gov/~newsom/Doppler/offsite/xpia/Halo/


This includes the "raw" radial velocity data, as well as processed VAD winds, and vertical velocity statistics (variance, skewness, kurtosis, cloud base height, cloud fraction, cloud base vertical velocity, and velocity precision estimates).


The Halo maintained a consistent scan schedule throughout its deployment period (from March 6th to April 16th). The scan schedule was as follows:

• 8 beam PPI scan at 60 deg elevation once every 12 minutes.
• narrow sector scan toward light posts near the EHS stadium once per day.
• ~10 minute slant-path stare near 50-m level on the BAO tower once per hour.
• Vertical stares the rest of the time.

The Halo was operated using a 30-m gate size, and with a 1-second pulse integrate time. The maximum number of gates was set to 200. With the exception of a fairly minor software glitch on the April 9, the Halo functioned quite well. The glitch resulted in downtime during the latter half of April 9th, all of the 10th, and the first half of April 11th.

Motion Table April 24, 2015
Looks very cool, especially when moving.
What you see is the motion table mounted on the trailer with the Vindicator "Egg" sitting on the platform. The trailer sits inside a wind screen/break.

The air compressor that provides power to the motion arms is covered by the blue tarp off to the left.

BAO 300m T/RH
Now the fan on this sensor has gone bad.  We measure the fan current and our software removes data when the fan is not operating.  We could use the data, but they would be contaminated by a radiative heating error.

Replacement being prepared by NCAR and will be replaced some time next week.

All other sensors working.

3D Volume Scans

Over the last three days, the four 200S lidars and HRDL were engaged in testing various configurations of volume scans to measure and visualize flow behind a wind turbine.  With this goal, the following two configurations were tested.

1. Small box pattern:

This pattern has a high update rate of once every 15 sec.  It envelops a small volume of 100mX100m and from 30m above ground to 130m above ground.  This pattern is focused on producing retrievals just behind or ahead of a wind turbine.

2. Medium box pattern:

This pattern covers a slightly larger volume of approx 400mX400m and from surface to 200m above the ground with ~15m vertical resolution at each of the scan intersections.  Due to the larger area coverage the update rate is reduced to once every 1 min.

Sonde Schedule

Weather warning - hard hats recommended near the guy wires due to chance for falling ice

Posting for Dan Wolfe:

The situation at the BAO is extremely wet, slushy, and messy. Over 1.5" of precip have fallen, which is a lot of this site, so even the roads are likely to be complicated. There could be slush or possible ice on the tower and guys, so activity near the guys should include using hard hats (available in the Visitor Center and in the trailer at the tower base) in case of ice falling from the guy wires.

UTD 200S: Assessment of LiDAR measurements against sonic anemometry

The UTD team is working on the intercomparison between the radial velocity measured by the UTD WindCube 200S and the 3D velocity measurements carried out with the CSAT3 sonic anemometers installed over the met-tower. In this post measurements performed in proximity of the sonic anemometer installed on the South-East boom at height of 50 m are shown. For this test the UTD 200S measured with an elevation angle of 11.49 deg, and the azimuthal angle between the laser beam and the SE boom was 98 deg. The three wind velocity components measured by the CSAT3 are retrieved in order to obtain the equivalent radial velocity seen by the UTD 200S. In Fig. 1 the comparison between the radial velocity retrieved from the sonic data and the one measured by the UTD 200S clearly shows a very good agreement between the two measurement techniques. These data were acquired from 2015-03-22 16:00:08.806244 UTC till 2015-03-22 16:14:38.285902 UTC. For this analysis no temporal correction was performed, assessing the time synchronization of the LiDAR carried out with the embedded GPS. 

Fig. 1: Comparison between the 3D velocity data obtained from the CSAT3 sonic anemometer and the radial velocity measured by the UTD 200S.

  In the following some numbers to quantify the LiDAR accuracy:

Mean value for the lidar radial velocity: -3.07 m/s

Mean value for the sonic radial velocity : -2.91 m/s

Standard deviation for the lidar radial velocity: 0.32 m/s

Standard deviation for the sonic radial velocity: 0.42 m/s 

The higher standard deviation of the sonic data is connected to the higher sampling rate (20 Hz for the sonic and 2 Hz for the LiDAR) and smaller sampling volume (30 cm for the sonic, 50 m for the LiDAR).

In Fig. 2 a zoom in of the comparison between the sonic and LiDAR data is reported.

Fig. 2: Comparison between the radial velocity measured by the UTD 200S and the one retrieved by the sonic anemometer CSAT3 installed on the SE boom at 50 m height.

Finally, accuracy of the LiDAR measurements can be better appreciated when LiDAR data are compared with the wind shear measured by the sonic anemometers deployed at different heights.

Fig. 3: Intercomparison between the UTD 200S measurements performed in proximity of the sonic anemometer at 50 m height and the wind data acquired by the sonic anemometers deployed at different heights.

The regression analysis of the LiDAR data vs the sonic anemometer data shows a slope of  1.072 and an R-squared value of 0.6682 (Fig. 4).

Fig. 4: Linear regression between LiDAR data and sonic anemometer data.

Motion Table
For those of you who can't make it out to the site, here are a couple of pictures of the motion table.

Temperature Profiles at Watertank

Last Friday a Kipp & Zonen Microwave Temperature Profiler (MTP-5) was installed at the LeftHand Water District site (a.k.a. Watertank). Below the timeseries for Saturday and Sunday (top and bottom images, respectively). This instrument is generating a temperature profile every 5 minutes with a vertical resolution of 50 m from the surface up to 1 km. 

Figure 1. Microwave temperature profiler timeseries for April 11 (top) and 12 (bottom), 2014.

Updated tower files

A very small error in boom orientation (3 degrees) has been identified, and Gordon Maclean from NCAR has corrected the datafiles as of 13 Apr. Gordon says:

The netcdf files have been reprocessed with updated boom azimuths of 154 and 334.

This includes the 5 minute files at ftp://ftp.eol.ucar.edu/pub/archive/isff/projects/cabl/netcdf_qc_geo_notiltcor

and the high rate files at ftp://ftp.eol.ucar.edu/pub/archive/isff/projects/cabl/netcdf_hr_qc_geo_notiltcor

The high rate files have also been re-formatted. They now contain 12 hours of data instead of 4, and so for each day the files are named cabl_ntc_YYYYMMDD_HH.nc, where HH is 00 and 12.   If you've downloaded high-rate files before, you should replace the 00 and 12 files with the new ones and delete files with HH fields of  04,08,16 and 20.

BAO 2015-04-13
All tower sensors working. Strong winds over weekend...all booms secure.

NOAA radiometer pressure way off and not tracking.

UTD 200s: RHIs and Virtual tower experiment

The UTD 200S and the two NOAA 200S have been performing simultaneous Range-height indicator (RHI) scans, which are performed by keeping fixed the azimuthal angle of the scanning head and sweeping the elevation angle within a certain range. The three LiDARs performed scans by intersecting the three measurements plans in correspondence of the lidar supersite location, in proximity of the SE sonic anemometers of the met-tower, and over another location where the TTU ka-band radar was also performing virtual tower measurements. Preliminary data analysis shows the characterization of wind shear and low level jet through the RHI measurements.

  Fig. 1: RHI scans during the occurrence of a Low-Level Jet.

Fig. 2: Wind shear characterized through RHI scans.

Fig. 3: Wind shear characterized through RHI scans.

Rotated radimeters for low-level scans @ 0deg elevation angle

The radiometers were rotated by 90 degrees on Tuesday (7 April) scanning now east-west instead of north south. This allows for low-level scans at 0deg elevation angle. Attached is a figure showing the new configuration looking towards SW.