TWP/DL/C3 - No signal

Laser and/or detection system failed resulting in no signal. The radial velocity and 
backscatter measurements are nothing but pure noise, i.e. no atmospheric signal.

• intensity
• Radial velocity(radial_velocity)
• Attenuated backscatter(attenuated_backscatter)

TWP/DL/C3 - Fault in RF attenuator

The instrument was shipped to the vendor (Halo Photonics) for repair. The root cause of 
the problem was traced to an intermittent fault in an RF attenuator in the transmitter. The 
RF attenuator was replaced. 

In addition to the repair, several upgrades were performed. These included the 
installation of a new PC with Win7, new control software, and the installation of a tip-tilt sensor.

• intensity
• Radial velocity(radial_velocity)
• Attenuated backscatter(attenuated_backscatter)

TWP/DL/DLPROF/C3 - Instrumental artifact in vertical velocity variance profiles

Long-term averages of vertical velocity variance profiles developed from vertical staring 
data show a height-dependent sinusoidal modulation superimposed on the atmospheric 
variance profile. This modulation causes a wiggle in the variance profile. The period of the 
wiggle is about 350 m, and the effect is most obvious during hot afternoon periods in the 
summer months. The exact cause of this problem is not known, but we suspect that it may be 
caused by temperature sensitivity in beam alignment.

• Radial velocity(radial_velocity)