SGP/CEIL/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
• Backscatter, ceilometer, range and sensitivity corrected(backscatter)

SGP/CEIL/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.

• Backscatter, ceilometer, range and sensitivity corrected(backscatter)

SGP/CEIL/C1/B4/B5/B6 - Reprocess: Incorrect serial_number and sum_backscatter fields

Attribute serial_number: In most cases, this field is not representative of the actual 
serial number of the instrument because the value did not change when an instrument changed 
locations or was replaced with a spare.

Variable sum_backscatter: An out-of-range condition for the "sum of detected and 
normalized backscatter" was reported as 0 instead of missing (-9999). The valid range is 0 - 
0.0999 /srad.

This DQR also applies to a1 level data collected prior to b1 level.

• sum_backscatter

SGP/CEIL/C1 - Range normalization

The range gate data were not normalized during this period because, when the CL31 was 
first deployed, I was uncertain about this parameter and returned it to its default setting 
of "off". Range gate normalization was enabled after receiving the following from Vaisala:

''We do recommend to keep this 'profile noise_h2' setting on. If 'profile noise_h2' is 
off, then range correction of the signal would freeze at 2400 m, unless the algorithm has 
detected a cloud region. This had been designed to make profiles in CL-VIEW look less noisy 
and to emphasize the presence of clouds.''

• Cloud, base height, lowest base sensed(first_cbh)
• Third cloud base height(third_cbh)
• alt_highest_signal
• Cloud, base height, second lowest base sensed(second_cbh)
• vertical_visibility
• Backscatter, ceilometer, range and sensitivity corrected(backscatter)

SGP/CEIL/C1 - Contaminated window

Alarm shown: Light Path Obstruction and Window Contamination. Window condition was 2%. 
Observed massive amounts of bird droppings on window. Cleaned window and shortly after 
window condition had risen to 94% and alarm was cleared.

• Cloud, base height, lowest base sensed(first_cbh)
• Third cloud base height(third_cbh)
• alt_highest_signal
• sum_backscatter
• Cloud, base height, second lowest base sensed(second_cbh)
• detection_status
• vertical_visibility
• background_light
• Backscatter, ceilometer, range and sensitivity corrected(backscatter)

SGP - Data System Upgrades: Data Missing

The data system was undergoing upgrades.  Data were lost during this period.

• qc_second_cbh
• Altitude above mean sea level(alt)
• alt_highest_signal
• North latitude(lat)
• time_offset
• Cloud, base height, second lowest base sensed(second_cbh)
• qc_background_light
• measurement_parameters
• qc_first_cbh
• tilt_angle
• range_bounds
• base_time
• status_flag
• qc_window_contamination
• sum_backscatter
• detection_status
• range
• qc_laser_pulse_energy
• vertical_visibility
• background_light
• qc_third_cbh
• East longitude(lon)
• time_bounds
• qc_sum_backscatter
• qc_alt_highest_signal
• laser_temperature
• qc_receiver_sensitivity
• laser_pulse_energy
• Cloud, base height, lowest base sensed(first_cbh)
• qc_tilt_angle
• qc_laser_temperature
• Third cloud base height(third_cbh)
• time
• window_contamination
• qc_window_transmission
• status_string
• qc_vertical_visibility
• window_transmission
• Backscatter, ceilometer, range and sensitivity corrected(backscatter)
• receiver_sensitivity