SGP/VCEIL/B1 - Ice storm

Data missing due to severe ice storm.

• Vertical visibility(vertical_visibility)
• lat(lat)
• Aerosol backscatter coefficient at 355 nm(backscatter)
• Warning and alarm status bits(status_string)
• Detection status. See details(detection_status)
• Second lowest cloud base height(second_cbh)
• Flag indicating aeri retrieval status(status_flag)
• Degrees from vertical (0 to +90)(tilt_angle)
• Backscatter sum(sum_backscatter)
• Third cloud base height(third_cbh)
• 6 character string describing instrument measurement parameters(measurement_parameters)
• Altitude of highest signal(alt_highest_signal)
• Percentage of nominal factory setting (0 to 999%)(receiver_sensitivity)
• Time offset of tweaks from base_time(time_offset)
• Lowest cloud base height detected.(first_cbh)
• lon(lon)
• Dummy altitude for Zeb(alt)
• base time(base_time)
• Laser temperature(laser_temperature)
• Millivolts at internal ADC input (0 to 2500)(background_light)
• Millivolts at internal ADC input(window_contamination)
• Percentage of nominal factory setting (0 to 999%)(laser_pulse_energy)
• range(range)

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/C1 - poor signal

When parameters were changed (set noise_h2_compensation to "ON" and units to "METERS") to 
correct a low amplitude problem, the backscatter plots began displaying horizontal 
stripes indicating detector "ringing". However, the cloud base heights are not affected. The 
problem was corrected when the instrument was replaced.

• Detection status. See details(detection_status)
• Aerosol backscatter coefficient at 355 nm(backscatter)

SGP/VCEIL/B5 - Backscatter noise affects cloud detection

Performance of the instrument degraded resulting in very noisy backscatter data to the 
extent that cloud detection was severely impacted beyond approximately 3 km (day and night).

• Second lowest cloud base height(second_cbh)
• Third cloud base height(third_cbh)
• Vertical visibility(vertical_visibility)
• Aerosol backscatter coefficient at 355 nm(backscatter)
• Altitude of highest signal(alt_highest_signal)
• Lowest cloud base height detected.(first_cbh)

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)