Data Quality Reports for Session: 104353 User: osatya Completed: 02/19/2007


TABLE OF CONTENTS

DQR IDSubjectData Streams Affected
D060113.1TWP/VCEIL/C3 - low receiver sensitivitytwpvceil25kC3.b1
D061220.34TWP/VCEIL/C3 - standard instrument installedtwpvceil25kC3.b1
D070201.1TWP/VCEIL/C3 - Reduced sensitivity to high cloudstwpvceil25kC3.b1


DQRID : D060113.1
Start DateStart TimeEnd DateEnd Time
12/12/2005055505/18/20062300
Subject:
TWP/VCEIL/C3 - low receiver sensitivity
DataStreams:twpvceil25kC3.b1
Description:
The ceilometer reported frequent receiver alarms. There are periods when the receiver 
sensitivity dropped to about 50%. The problem was corrected by replacing the instrument with 
a spare.
Measurements:twpvceil25kC3.b1:
  • Lowest cloud base height detected.(first_cbh)
  • Vertical visibility(vertical_visibility)
  • Aerosol volume backscattering coefficient at 355 nm(backscatter)
  • SUM of detected and normalized backscatter(sum_backscatter)
  • Second lowest cloud base height(second_cbh)
  • Third cloud base height(third_cbh)
  • Percentage of nominal factory setting (0 to 999%)(receiver_sensitivity)
  • Altitude of highest signal(alt_highest_signal)
  • Millivolts at internal ADC input (0 to 2500)(background_light)


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DQRID : D061220.34
Start DateStart TimeEnd DateEnd Time
05/18/2006230012/20/20060400
Subject:
TWP/VCEIL/C3 - standard instrument installed
DataStreams:twpvceil25kC3.b1
Description:
A spare ceilometer without the tropics window option was installed. The manufacturer 
recommends the tropics window be used at +/- 25 deg lattitude to prevent direct solar 
radiation into the laser optics when the instrument pointed at zenith. No significant signal 
degradation is apparent during the autumnal equinox but, as a precaution, the unit was 
replaced with the original with a tropics window.
Measurements:twpvceil25kC3.b1:
  • Percentage of nominal factory setting (0 to 999%)(laser_pulse_energy)
  • Vertical visibility(vertical_visibility)
  • Aerosol volume backscattering coefficient at 355 nm(backscatter)
  • SUM of detected and normalized backscatter(sum_backscatter)
  • Laser temperature(laser_temperature)
  • Millivolts at internal ADC input (0 to 2500)(background_light)


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DQRID : D070201.1
Start DateStart TimeEnd DateEnd Time
12/20/2006040101/12/20070120
Subject:
TWP/VCEIL/C3 - Reduced sensitivity to high clouds
DataStreams:twpvceil25kC3.b1
Description:
The instrument produced a significant number of optical cross-talk warnings and displayed 
a reduced capacity to detect high clouds.  The internal cables were inspected, the 
compensation fiber and optics monitor were replaced, the crosstalk compensation was adjusted, 
and the system tested with an optical termination hood, all with no improvement.  While 
waiting for a new receiver board, receiver ribbon cable, and compensation fiber cable from 
Vaisala, a spare ceilometer with a standard, "non-tropics", window was installed.
Measurements:twpvceil25kC3.b1:
  • Second lowest cloud base height(second_cbh)
  • Third cloud base height(third_cbh)
  • Percentage of nominal factory setting (0 to 999%)(receiver_sensitivity)
  • Altitude of highest signal(alt_highest_signal)
  • Detection status. See details(detection_status)


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