SGP/VCEIL/B1  - recurrent frequent data gaps

Beginning on 07/06/2003, frequent short-term data gaps began occurring. The situation 
continued to worsen until the PC locked up entirely on 07/14/2003.  After the computer was 
re-booted, the data gaps stopped and have not returned.  The problem appears to be 
restricted entirely to the computer and does not involve the ceilometer itself.  Thus, there 
appears to be no problem with the data records that were properly collected.

• Vertical visibility(vertical_visibility)
• Time offset of tweaks from base_time(time_offset)
• Lowest cloud base height detected.(first_cbh)
• Millivolts at internal ADC input (0 to 2500)(background_light)
• Aerosol backscatter coefficient at 355 nm(backscatter)
• lat(lat)
• Warning and alarm status bits(status_string)
• Second lowest cloud base height(second_cbh)
• Degrees from vertical (0 to +90)(tilt_angle)
• Altitude of highest signal(alt_highest_signal)
• Percentage of nominal factory setting (0 to 999%)(receiver_sensitivity)
• Percentage of nominal factory setting (0 to 999%)(laser_pulse_energy)
• Millivolts at internal ADC input(window_contamination)
• Flag indicating aeri retrieval status(status_flag)
• Backscatter sum(sum_backscatter)
• 6 character string describing instrument measurement parameters(measurement_parameters)
• Laser temperature(laser_temperature)
• Detection status. See details(detection_status)
• Third cloud base height(third_cbh)
• lon(lon)
• Dummy altitude for Zeb(alt)
• base time(base_time)
• range(range)

• Parameter scale(parameter_scale)
• Aerosol backscatter coefficient at 355 nm(backscatter)
• Starting elevations(altitude_tags)
• lon(lon)
• range(range)
• Lowest cloud base height detected.(first_cbh)
• Laser temperature(laser_temperature)
• GPS raw data filename(filename)
• Detection status. See details(detection_status)
• Lowest cloud base height detected.(lowest_cloud_base_ht)
• lat(lat)
• Warning and alarm status bits(status_string)
• base time(base_time)
• Millivolts at internal ADC input(window_contamination)
• Third cloud base height(third_cbh)
• Degrees from vertical (0 to +90)(tilt_angle)
• Backscatter sum(sum_backscatter)
• Millivolts at internal ADC input (0 to 2500)(background_light)
• Percentage of nominal factory setting (0 to 999%)(receiver_sensitivity)
• Time offset of tweaks from base_time(time_offset)
• Vertical visibility(vertical_visibility)
• Percentage of nominal factory setting (0 to 999%)(laser_pulse_energy)
• Dummy altitude for Zeb(alt)
• Second lowest cloud base height(second_cbh)
• 6 character string describing instrument measurement parameters(measurement_parameters)
• Flag indicating aeri retrieval status(status_flag)
• Altitude of highest signal(alt_highest_signal)

• null(Raw data stream - documentation not supported)

SGP/VCEIL/B4 - Receiver failure

The receiver failed abruptly just a few minutes after 00:00 UTC on  Dec. 12, 2002.  The 
problem was resolved by replacement of the broken ceilometer with a working ceilometer on 
Jan. 10, three days after the problem was PIFed.

• null(Raw data stream - documentation not supported)

• range(range)
• GPS raw data filename(filename)
• Lowest cloud base height detected.(first_cbh)
• Time offset of tweaks from base_time(time_offset)
• Parameter scale(parameter_scale)
• Warning and alarm status bits(status_string)
• Dummy altitude for Zeb(alt)
• Backscatter sum(sum_backscatter)
• lon(lon)
• Laser temperature(laser_temperature)
• Altitude of highest signal(alt_highest_signal)
• Millivolts at internal ADC input(window_contamination)
• Aerosol backscatter coefficient at 355 nm(backscatter)
• Vertical visibility(vertical_visibility)
• Percentage of nominal factory setting (0 to 999%)(laser_pulse_energy)
• Percentage of nominal factory setting (0 to 999%)(receiver_sensitivity)
• Detection status. See details(detection_status)
• 6 character string describing instrument measurement parameters(measurement_parameters)
• Flag indicating aeri retrieval status(status_flag)
• Starting elevations(altitude_tags)
• lat(lat)
• Second lowest cloud base height(second_cbh)
• Third cloud base height(third_cbh)
• Millivolts at internal ADC input (0 to 2500)(background_light)
• base time(base_time)
• Lowest cloud base height detected.(lowest_cloud_base_ht)
• Degrees from vertical (0 to +90)(tilt_angle)

• Degrees from vertical (0 to +90)(tilt_angle)
• Millivolts at internal ADC input(window_contamination)
• Detection status. See details(detection_status)
• lat(lat)
• Laser temperature(laser_temperature)
• Warning and alarm status bits(status_string)
• Time offset of tweaks from base_time(time_offset)
• Backscatter sum(sum_backscatter)
• Dummy altitude for Zeb(alt)
• Altitude of highest signal(alt_highest_signal)
• Lowest cloud base height detected.(first_cbh)
• Percentage of nominal factory setting (0 to 999%)(receiver_sensitivity)
• lon(lon)
• base time(base_time)
• 6 character string describing instrument measurement parameters(measurement_parameters)
• range(range)
• Second lowest cloud base height(second_cbh)
• Percentage of nominal factory setting (0 to 999%)(laser_pulse_energy)
• Flag indicating aeri retrieval status(status_flag)
• Third cloud base height(third_cbh)
• Vertical visibility(vertical_visibility)
• Aerosol backscatter coefficient at 355 nm(backscatter)
• Millivolts at internal ADC input (0 to 2500)(background_light)

SGP/VCEIL/B4 - Detection optics degrading

Backscatter plots exhibited horizontal striping due to electronic ringing of either the 
detector or the associated amplification electronics.  The instrument was changed out on 
May 10.

The ceilometer continued to correctly detected clouds during this period, though users 
should be aware of the degraded performance.

• Aerosol backscatter coefficient at 355 nm(backscatter)