SGP/VCEIL/B5 - Noisy Backscatter

Since October of 2004, the noise in the backscatter plots occasionally become high in 
amplitude for periods of time lasting anywhere from an hour or so to as much as a day. This 
problem appears similar to a dirty window (such as the problem at B6 last week), but the 
fact that the plots show high amplitude for short durations of time imply that this 
problem is different.

Cloud base height detection appears to be unaffected.

• Aerosol backscatter coefficient at 355 nm(backscatter)

SGP/VCEIL/B4 - Detection optics degrading

Backscatter plots exhibited horizontal striping due to electronic ringing of either the 
detector or the associated amplification electronics.  The instrument was changed out on 
May 10.

The ceilometer continued to correctly detected clouds during this period, though users 
should be aware of the degraded performance.

• Aerosol backscatter coefficient at 355 nm(backscatter)

SGP/VCEIL/C1 - low amplitude

When the instrument was replaced with a spare, the backscatter plots began displaying a 
suspiciously low amount of amplitude (noise) but the cloud base heights were not affected. 

Discovered that when the vendor repaired this unit in August 2004, noise compensation was 
set to "OFF". Changed the parameters to "ON".

Also noted that the measurement units was set to "FEET".  This was changed to "METERS.  
The heights are not affected because the ingest recognizes the raw data units and 
automatically converts to meters.

• Aerosol backscatter coefficient at 355 nm(backscatter)