Data Quality Reports for Session: 100217 User: yasunaga Completed: 06/26/2006


TABLE OF CONTENTS

DQR IDSubjectData Streams Affected
D021212.11TWP/VCEIL/C3 - Degraded Sensitivity, Limited Rangetwpvceil25kC3.a1, twpvceil25kC3.b1
D040506.1TWP/VCEIL/C3 - Data collection problemtwpvceil25kC3.00, twpvceil25kC3.b1
D051209.4TWP/VCEIL/C3 - Degraded hardwaretwpvceil25kC3.b1
D051216.6TWP/VCEIL/C3 - ceilometer lost sensitivitytwpvceil25kC3.b1


DQRID : D021212.11
Start DateStart TimeEnd DateEnd Time
11/06/20020012/09/200200
Subject:
TWP/VCEIL/C3 - Degraded Sensitivity, Limited Range
DataStreams:twpvceil25kC3.a1, twpvceil25kC3.b1
Description:
The Darwin ceilometer was displaying a cross-talk warning during this
period. This causes degraded sensitivity and the inability of the 
ceilometer to identify cloud heights that are higher the about 2 km.
Measurements:twpvceil25kC3.a1:
  • Third cloud base height(third_cbh)
  • Lowest cloud base height detected.(first_cbh)
  • Second lowest cloud base height(second_cbh)
  • Aerosol volume backscattering coefficient at 355 nm(backscatter)
  • Vertical visibility(vertical_visibility)
  • Altitude of highest signal(alt_highest_signal)

twpvceil25kC3.b1:
  • Lowest cloud base height detected.(first_cbh)
  • Vertical visibility(vertical_visibility)
  • Aerosol volume backscattering coefficient at 355 nm(backscatter)
  • Second lowest cloud base height(second_cbh)
  • Third cloud base height(third_cbh)
  • Altitude of highest signal(alt_highest_signal)


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DQRID : D040506.1
Start DateStart TimeEnd DateEnd Time
04/01/20040005/07/200400
Subject:
TWP/VCEIL/C3 - Data collection problem
DataStreams:twpvceil25kC3.00, twpvceil25kC3.b1
Description:
There was a bad connection between the ceilometer and the instrument computer which 
resulted in a small amount of data loss on 8 days during the effected period.  The data that 
were collected are not effected by the problem.  On April 11, 34% of the data was lost and 
on April 1, 4% was lost.  On the remaining 6 days, May 1-6, the amount of data lost was 
less than 2%/day.
Measurements:twpvceil25kC3.00:
  • Raw data stream - documentation not supported(Raw data stream - documentation not supported)

twpvceil25kC3.b1:
  • Vertical visibility(vertical_visibility)
  • SUM of detected and normalized backscatter(sum_backscatter)
  • Time offset of tweaks from base_time(time_offset)
  • Second lowest cloud base height(second_cbh)
  • Time offset from base_time(base_time)
  • Laser temperature(laser_temperature)
  • Altitude of highest signal(alt_highest_signal)
  • Warning and alarm status bits(status_string)
  • Millivolts at internal ADC input (0 to 2500)(background_light)
  • north latitude for all the input platforms.(lat)
  • Degrees from vertical (-15 to +90)(tilt_angle)
  • Lowest cloud base height detected.(first_cbh)
  • Percentage of nominal factory setting (0 to 999%)(laser_pulse_energy)
  • east longitude for all the input platforms.(lon)
  • Aerosol volume backscattering coefficient at 355 nm(backscatter)
  • Flag indicating aeri retrieval status(status_flag)
  • altitude above sea levelaltunits(alt)
  • Third cloud base height(third_cbh)
  • 6 character string describing instrument measurement parameters(measurement_parameters)
  • Millivolts at internal ADC input(window_contamination)
  • Percentage of nominal factory setting (0 to 999%)(receiver_sensitivity)
  • distance to center of range bin after correcting for offset in sync(range)
  • Detection status. See details(detection_status)


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DQRID : D051209.4
Start DateStart TimeEnd DateEnd Time
09/16/20050012/12/200555
Subject:
TWP/VCEIL/C3 - Degraded hardware
DataStreams:twpvceil25kC3.b1
Description:
It appears that the sensitivity of the Darwin ceilometer was degrading over a few month 
period leading up to September 2005.  Beginning on September 16, 2005, the instrument 
shifted to a particularly bad state.  Looking at the backscatter data, I do not see nearly as 
great a day-night difference in the background as I expect and there is very little 
sensitivity to clouds.  There was cross talk error noted with that instrument. The ceilometer 
was replaced on December 12.
Measurements:twpvceil25kC3.b1:
  • Lowest cloud base height detected.(first_cbh)
  • Vertical visibility(vertical_visibility)
  • Aerosol volume backscattering coefficient at 355 nm(backscatter)
  • Second lowest cloud base height(second_cbh)
  • Third cloud base height(third_cbh)
  • Altitude of highest signal(alt_highest_signal)
  • Millivolts at internal ADC input (0 to 2500)(background_light)


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DQRID : D051216.6
Start DateStart TimeEnd DateEnd Time
09/16/200523012/12/200550
Subject:
TWP/VCEIL/C3 - ceilometer lost sensitivity
DataStreams:twpvceil25kC3.b1
Description:
ceilometer sesitivity decreased suddenly and only very strong cloud reflections are 
observed in the first kilometer.
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)
  • Flag indicating aeri retrieval status(status_flag)
  • Second lowest cloud base height(second_cbh)
  • Third cloud base height(third_cbh)
  • Warning and alarm status bits(status_string)
  • distance to center of range bin after correcting for offset in sync(range)
  • Detection status. See details(detection_status)
  • Millivolts at internal ADC input (0 to 2500)(background_light)


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