SGP/VCEIL/B5 - REPROCESS: CBH reported in feet but labeled meters

The cloud base heights reported in the file are in feet despite being labelled meters.  
Reprocessing of this data is highly recommended.

The first affected file is from 2001-05-27 when the ceilometer was exchanged with a 
repaired one.  The last affected file is on 2001-12-13 when the new vceil_ingest version 7.2 
was released which applies the proper units conversion from feet to meters.

• lowest_cloud_base_ht
• Second lowest cloud base height(second_cbh)
• alt
• Vertical visibility(vertical_visibility)
• alt_highest_signal
• Lowest cloud base height detected.(first_cbh)
• Third cloud base height(third_cbh)

• Third cloud base height(third_cbh)
• Vertical visibility(vertical_visibility)
• Second lowest cloud base height(second_cbh)
• Lowest cloud base height detected.(first_cbh)
• alt_highest_signal
• alt

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.

• Backscatter(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)
• alt_highest_signal
• Lowest cloud base height detected.(first_cbh)
• Vertical visibility(vertical_visibility)
• Backscatter(backscatter)

SGP/VCEIL/B5 - Degraded hardware

Following repair at Vaisala and re-installation on 10/23/2007, the ceilometer experiencing 
intermittent receiver alarms and discontinuities in the backscatter plot. Vaisala 
recommended the old firmware card be replaced but that did not resolve the problems. The 
instrument was replaced with a spare and returned to the vendor for repair.

• detection_status
• laser_temperature
• Third cloud base height(third_cbh)
• status_flag
• background_light
• Vertical visibility(vertical_visibility)
• Backscatter(backscatter)
• range
• Second lowest cloud base height(second_cbh)
• sum_backscatter
• receiver_sensitivity
• status_string
• measurement_parameters
• laser_pulse_energy
• Lowest cloud base height detected.(first_cbh)
• alt_highest_signal
• window_contamination
• tilt_angle

SGP/VCEIL/B5 - Missing data

Data are missing and unrecoverable.

• detection_status
• laser_temperature
• Third cloud base height(third_cbh)
• base_time
• status_flag
• lat
• background_light
• Vertical visibility(vertical_visibility)
• Backscatter(backscatter)
• range
• sum_backscatter
• Second lowest cloud base height(second_cbh)
• lon
• receiver_sensitivity
• status_string
• measurement_parameters
• laser_pulse_energy
• alt_highest_signal
• Lowest cloud base height detected.(first_cbh)
• window_contamination
• alt
• tilt_angle
• time_offset

SGP/VCEIL/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

• sum_backscatter

• sum_backscatter

• sum_backscatter