NSA/VCEIL/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.

• Warning, alarm, and internal status information(status_string)
• Millivolts at internal ADC input (0 to 2500)(background_light)
• Percentage of nominal factory setting (0 to 999%)(receiver_sensitivity)
• Sum of detected and normalized backscatter(sum_backscatter)
• Percentage of nominal factory setting (0 to 999%)(laser_pulse_energy)
• Window contamination(window_contamination)
• Vertical visibility(vertical_visibility)
• Distance to the center of the corresponding range bin(range)
• Flag indicating aeri retrieval status(status_flag)
• 6 character string describing instrument measurement parameters(measurement_parameters)
• Detection status.(detection_status)
• Aerosol volume backscattering coefficient at 355 nm(backscatter)
• Degrees from vertical (-15 to +90)(tilt_angle)
• Lowest cloud base height detected(first_cbh)
• Time offset from base_time(time_offset)
• base time in epoch(base_time)
• Third cloud base height(third_cbh)
• Second lowest cloud base height(second_cbh)
• Laser temperature(laser_temperature)
• Altitude of highest signal(alt_highest_signal)