NSA/CEIL/C1 - Occasional Data Transmission problems

During this period, there were occasional data transmission problems that lead to cut-off 
data packets at times. These disappeared after ceilometer computer were replaced.

• laser_pulse_energy
• measurement_parameters
• window_contamination
• East longitude(lon)
• filename
• North latitude(lat)
• laser_temperature
• range
• detection_status
• alt_highest_signal
• base_time
• Lowest cloud base height detected.(first_cbh)
• background_light
• Third cloud base height(third_cbh)
• status_string
• Backscatter, ceilometer, range and sensitivity corrected(backscatter)
• sum_backscatter
• time_offset
• receiver_sensitivity
• tilt_angle
• status_flag
• Altitude above mean sea level(alt)
• vertical_visibility
• Cloud, base height, second lowest base sensed(second_cbh)

NSA/CEIL/C1 - vceil25K Instrument maintenance

The instrument was calibrated during this period. To achieve this, it was pointed in the 
horizontal direction.

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

NSA/C1 - Site-wide power failure

The Barrow facility experienced a site-wide power failure on 12/13.  Power was restored to 
most instruments between 2250 and 2330 GMT.

• laser_pulse_energy
• measurement_parameters
• window_contamination
• East longitude(lon)
• filename
• North latitude(lat)
• laser_temperature
• range
• detection_status
• alt_highest_signal
• base_time
• Lowest cloud base height detected.(first_cbh)
• background_light
• Third cloud base height(third_cbh)
• status_string
• Backscatter, ceilometer, range and sensitivity corrected(backscatter)
• sum_backscatter
• time_offset
• receiver_sensitivity
• tilt_angle
• status_flag
• Altitude above mean sea level(alt)
• vertical_visibility
• Cloud, base height, second lowest base sensed(second_cbh)

NSA/CEIL/C1 - Reprocess: Intermittent data and clock drift

The available processed data for the NSA.C1 VCEIL for the time period indicated are 
incomplete.  The raw data is largely complete but pre-processing is required before these data 
can be reprocessed to produce a complete netcdf data set.

While awaiting the reprocessed data set, the intermittent data are available from the ARM 
Archive.  Users should be aware that the data are additionally compromised by a clock 
drift of at least 10 minutes, though this likely has little affect on cloud detection 
results.  The clock drift will not be addressed by the reprocessing.

Note also, that the clock drift was corrected at the end of the DQR period, but it may 
have existed before the beginning of the DQR period.

The data for this period should be used with caution.

• laser_pulse_energy
• measurement_parameters
• window_contamination
• East longitude(lon)
• filename
• North latitude(lat)
• laser_temperature
• range
• detection_status
• alt_highest_signal
• base_time
• Lowest cloud base height detected.(first_cbh)
• background_light
• Third cloud base height(third_cbh)
• status_string
• Backscatter, ceilometer, range and sensitivity corrected(backscatter)
• sum_backscatter
• time_offset
• receiver_sensitivity
• tilt_angle
• status_flag
• Altitude above mean sea level(alt)
• vertical_visibility
• Cloud, base height, second lowest base sensed(second_cbh)

NSA/CEIL/C1 - poor sensitivity at low altitude

The ceilometer has an internal amplifier that it sets to low or high depending on 
prevalant conditions. Normally, the gain is automatically set high during clear skies. It appears 
that during these times, a slight degradation in either the transmitter or receiver is 
being amplified and produces a "ripple" at low altitudes in the backscatter plot. Cloud 
base height detection is not affected.

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

NSA/CEIL/C1 - Degraded window

The ceilometer continuously gave warnings for window contamination because the window had 
deteriorated. Cloud base height detection did not appear to be significantly affected. 
The window conditioner was replaced on 8/11/09 but this did not clear the warning. The 
instrument was replaced.

• Third cloud base height(third_cbh)
• window_contamination
• status_string
• Backscatter, ceilometer, range and sensitivity corrected(backscatter)
• sum_backscatter
• alt_highest_signal
• status_flag
• Lowest cloud base height detected.(first_cbh)
• background_light
• vertical_visibility
• Cloud, base height, second lowest base sensed(second_cbh)

NSA/CEIL/C1 - Missing data

Data are missing and unrecoverable.

• laser_pulse_energy
• measurement_parameters
• window_contamination
• East longitude(lon)
• filename
• North latitude(lat)
• laser_temperature
• range
• detection_status
• alt_highest_signal
• base_time
• Lowest cloud base height detected.(first_cbh)
• background_light
• Third cloud base height(third_cbh)
• status_string
• Backscatter, ceilometer, range and sensitivity corrected(backscatter)
• sum_backscatter
• time_offset
• receiver_sensitivity
• tilt_angle
• status_flag
• Altitude above mean sea level(alt)
• vertical_visibility
• Cloud, base height, second lowest base sensed(second_cbh)

NSA/CEIL/C1/C2 - 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 and b1 level data collected prior to the begin date.

• sum_backscatter

NSA/CEIL/C1 - Small gaps in data

When the ceilometer was replaced, small gaps in the netCDF files occurred due to the 
presence of '?' characters in the backscatter and header records of the raw data that could 
not be ingested. It is unknown whether this was caused by a poor CPU board or 
incompatibilities with the computer configuration (hyper-threading). The problem was corrected when 
the instrument and computer were both replaced. 

During this period, approximately 3% of data are missing each hour due to this problem.

• laser_pulse_energy
• measurement_parameters
• window_contamination
• range
• laser_temperature
• detection_status
• alt_highest_signal
• base_time
• Lowest cloud base height detected.(first_cbh)
• background_light
• Third cloud base height(third_cbh)
• status_string
• Backscatter, ceilometer, range and sensitivity corrected(backscatter)
• sum_backscatter
• time_offset
• receiver_sensitivity
• tilt_angle
• status_flag
• vertical_visibility
• Cloud, base height, second lowest base sensed(second_cbh)

NSA/CEIL/C1 - Gaps in data

When the CT25K ceilometer was replaced with a new CL31, checksum errors began occurring at 
regular 6-min intervals and several things were done to diagnose the problem, including 
changing the serial cable and trying different computer types. It was finally corrected 
by replacing the computer with one in which hyperthreading was disabled by default in the 
BIOS.

• laser_pulse_energy
• measurement_parameters
• window_contamination
• range
• laser_temperature
• detection_status
• alt_highest_signal
• base_time
• Lowest cloud base height detected.(first_cbh)
• background_light
• Third cloud base height(third_cbh)
• status_string
• Backscatter, ceilometer, range and sensitivity corrected(backscatter)
• sum_backscatter
• time_offset
• receiver_sensitivity
• tilt_angle
• status_flag
• vertical_visibility
• Cloud, base height, second lowest base sensed(second_cbh)

NSA/CEIL/C1 - Reprocessed and Corrected: Time error

DATA REPROCESSED and CORRECTED: 

Time jumped forward an hour because the time zone was set to "(GMT) Greenwich Mean Time" 
with "Automatically adjust clock for Daylight Savings Time" selected. The time zone was 
changed to "(GMT) Coordinated Universal Time" and the clock reset to correct UTC time. Data 
for this time period have been corrected.

The data were archived in November 2016. Please retrieve the reprocessed data for use in 
your analysis. 


ORIGINAL DQR CATEGORY: Red( Incorrect)

REPROCESSED and CORRECTED DATA ARCHIVED:2016-11

REPROCESS IDENTIFICATION NUMBER: RID 923

---------------------------------------------------
--- ORIGINAL DQR DESCRIPTION ---
---------------------------------------------------


The computer time jumped forward an hour because the time zone was set to "(GMT) Greenwich 
Mean Time" with "Automatically adjust clock for Daylight Savings Time" selected. The 
time zone was changed to "(GMT) Coordinated Universal Time" and the clock reset to correct 
UTC time.

Correct time by subtracting 1 hour.

• time_offset

NSA/CEIL/C1 - Window blower failure may allow moisture/frost on the window

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

NSA/CEIL/C1 - Data Missing

Site data system was being upgraded during this time frame.

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

NSA/CEIL/C1 - Environmental

There appears to have been snow or ice on the window.

• Third cloud base height(third_cbh)
• sum_backscatter
• Lowest cloud base height detected.(first_cbh)
• vertical_visibility
• Cloud, base height, second lowest base sensed(second_cbh)