SGP/RL/C1 - Invalid liquid water channel data

On 20060906, the liquid water channel (LWC) was disabled due to the removal of its 
photomultiplier tube (PMT).  Consequently, the signals recorded for the LWC contain either zero 
or pure noise after that date.

Also, starting on 20070522, the LWC was populated with data from the T2 channel as a 
result of a slight reconfiguration of the data acquisition system.

On 4 March 2008 The LW channel photomultiplier tube was reinstalled in the Raman lidar. 
Effective 0000 UTC on 5 March 2008 the LW channel began producing valid liquid water data 
once again.

• Count rate in the high liquid channel(liquid_counts_high)
• Summed analog signal in the liquid water channel(liquid_analog_high)

SGP/RL/C1 - Invalid mode 0 data

On 20081112 the filter wheel for the wide field-of-view (WFOV) channel was incorrectly 
rotated. The net effect was that we were recording neutral density filter data when we 
should have been collecting data with the channels completely blocked (mode 0 data). As a 
result, the WFOV mode 0 data contains contributions from the pulse return and the solar 
background that should not be present. The mode 0 data is used in the rlprof_merge VAP to 
remove the electronic background level from the analog signal. After the problem was 
identified the filter wheel was set back to its proper rotation on 20090112.
A work-around has been implemented in the rlprof_merge VAP to handle the lack of valid 
mode 0 during the affected period. The work-around involves computing the electronic 
background from pre-pulse data during nighttime periods only. With this technique we are not 
able to estimate the range-dependence of the electronic backgound, as we did before. 
However, this range dependence is typically quite weak, and so the impact on the rlprof_merge 
output is expected to be minimal.

• Mean electronic background subtracted from the low channel water vapor analog
  signal(electronic_background_water_analog_low)
• Glue coefficient (offset) for low water vapor channel(water_counts_low_glue_coef_offset)
• Count rate in the low elastic channel(elastic_counts_low)
• Glue coefficient (slope) for low nitrogen channel(nitrogen_counts_low_glue_coef_slope)
• Count rate in the low nitrogen channel(nitrogen_counts_low)
• Count rate in the low water vapor channel(water_counts_low)
• Glue coefficient (slope) for low water vapor channel(water_counts_low_glue_coef_slope)
• Glue coefficient (slope) for low elastic channel(elastic_counts_low_glue_coef_slope)
• Mean electronic background subtracted from the low channel nitrogen analog
  signal(electronic_background_nitrogen_analog_low)
• Glue coefficient (offset) for low nitrogen channel(nitrogen_counts_low_glue_coef_offset)
• Mean electronic background subtracted from the low channel elastic analog signal(electronic_background_elastic_analog_low)
• Glue coefficient (offset) for low elastic channel(elastic_counts_low_glue_coef_offset)

• Summed analog signal in the low nitrogen channel(nitrogen_analog_low)
• Summed analog signal in the low elastic channel(elastic_analog_low)
• Summed analog signal in the low water vapor channel(water_analog_low)
• Count rate in the low elastic channel(elastic_counts_low)
• Count rate in the low nitrogen channel(nitrogen_counts_low)
• Count rate in the low water vapor channel(water_counts_low)