SGP/RL/C1 - Bad shot count data

The number of laser pulses averaged per profile, or shot count, exhibited erratic behavior 
during the periods in question. The values reported in the sgprlC1.a0 datastream were 
incorrect and varied radically from profile to profile. Shot counts are used in the Merge 
VAP to compute photon count rates, which are then used by all the other RL VAPs. Thus, the 
shot count problem renders all of the RL VAPs bad or suspect during the periods in question.
It appears that the problem was caused as the signal on the line between two triggering 
units got noisier over time, causing the second unit to occasionally trigger on noise. The 
second unit triggers the Licel electronics. So the false triggering on the second unit 
caused false shot count readings. On 6 October 2011 the trigger level was adjusted by the 
on-site technician, and this solved the problem.


On 3 May 2012 the DG535 pulse generator, which is used to trigger the Licel data 
recorders, was swapped out with a spare. After installation of the spare, the system started 
recording erroneous values of shot counts. The problem was fixed on 12 June 2012 when the 
on-site tech increased trigger level on the DG535.

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• Maximum altitude used in the calculation of the aerosol optical depth from the
  extinction_1 profile(aod_1_max_ht)
• Uncertainty of the aerosol extinction coefficient profile calculated from the
  aerosol backscatter coefficient(extinction_from_backscatter_error)
• Aerosol extinction coefficient profile from the high N2 channel data(extinction_high)
• Aerosol extinction coefficient profile created by marrying the merged extinction
  from N2 data with the extinction from backscatter data(extinction_married1)
• Uncertainty of the aerosol extinction coefficient profile from the low N2
  channel(extinction_low_error)
• Error in the aerosol optical depth calculated from the
  extinction_from_backscatter profile(aod_bscat_error)
• Vertical resolution of the low aerosol extinction coefficient profile data(extinction_low_resolution)
• Ratio of aerosol extinction to aerosol backscatter(Sa_1)
• Ratio of aerosol extinction to aerosol backscatter(Sa_2)
• Aerosol optical depth from the surface computed from the married1 extinction
  profiles(aod_married1_profile)
• Number of lidar pulses summed(shots_summed)
• Aerosol optical depth calculated from the extinction_from_backscatter profile(aod_bscat)
• Vertical resolution of the high aerosol extinction coefficient profile data(extinction_high_resolution)
• Aerosol optical depth calculated from the extinction_married1 profile(aod_married1)
• Error in the aerosol optical depth calculated from the extinction_married1
  profile(aod_married1_error)
• Uncertainty of the aerosol extinction coefficient profile from the high N2
  channel(extinction_high_error)
• Aerosol extinction coefficient profile calculated from backscatter and the
  extinction-to-backscatter ratio(extinction_from_backscatter)
• Aerosol optical depth from the surface computed from the extinction_1 profiles(aod_1_profile)
• Aerosol volume backscattering coefficient at 355 nm(backscatter)
• Mask indicating from where the extinction value came from in the aerosol
  extinction coefficient profile created by marrying the merged extinction from N2
  data w(extinction_married1_mask)
• Uncertainty of the aerosol extinction coefficient profile created by merging the
  two N2 channels extinction profiles(extinction_1_error)
• Vertical resolution of the merged aerosol extinction coefficient profile data(extinction_1_resolution)
• Aerosol optical depth from the surface computed from the
  extinction_from_backscatter profiles(aod_bscat_profile)
• Error in the aerosol optical depth calculated from the extinction_1 profile(aod_1_error)
• Aerosol backscatter coefficient at 355 nm - smoothed to N2 extinction resolution(smoothed_backscatter)
• Maximum altitude used in the calculation of the aerosol optical depth from the
  extinction_from_backscatter profile(aod_bscat_max_ht)
• Aerosol extinction coefficient profile from the low N2 channel data(extinction_low)
• Uncertainty of the married aerosol extinction coefficient profile(extinction_married1_error)
• Uncertainty in the aerosol backscatter coefficient at 355 nm(backscatter_error)
• Uncertainty in the aerosol backscatter coefficient at 355 nm - smoothed to N2
  extinction resolution(smoothed_backscatter_error)
• Flag denoting the occurrence of power or alignment tweaks(tweaks)
• Maximum altitude used in the calculation of the aerosol optical depth from the
  extinction_married1 profile(aod_married1_max_ht)
• Aerosol extinction coefficient profile created by merging the two N2 channels
  extinction profiles(extinction_1)
• Aerosol optical depth calculated from the extinction_1 profile(aod_1)
• Uncertainty of the aerosol extinction coefficient profile from the overlap
  corrected high N2 channel(extinction_high_olap_corrected_error)
• Aerosol extinction coefficient profile from the high N2 channel data, where the
  low N2 channel was used to correct for the overlap of the high channel(extinction_high_olap_corrected)

• Glue coefficient (slope) for high elastic channel(elastic_counts_high_glue_coef_slope)
• Glue coefficient (offset) for high nitrogen channel(nitrogen_counts_high_glue_coef_offset)
• Fit parameters for the low nitrogen channel(parameters_nitrogen_low)
• Glue coefficient (offset) for low nitrogen channel(nitrogen_counts_low_glue_coef_offset)
• Average cloud base height used in the retrieval(cbh)
• Glue coefficient (slope) for low water vapor channel(water_counts_low_glue_coef_slope)
• Number of photons counted in the high elastic (aerosol) channel(elastic_counts_high)
• Mean electronic background subtracted from the high channel water vapor analog
  signal(electronic_background_water_analog_high)
• 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)
• Number of photons counted in the liquid water channel(liquid_counts_high)
• Fit parameters for the high nitrogen channel(parameters_nitrogen_high)
• Adjustment to ensure solar background from AD and PC data are identical for the
  high liquid channel(solar_offset_nudge_lw)
• Glue coefficient (offset) for high water vapor channel(water_counts_high_glue_coef_offset)
• Mean electronic background subtracted from the high channel temperature #1
  analog signal(electronic_background_t1_analog_high)
• Mean electronic background subtracted from the high channel temperature #2
  analog signal(electronic_background_t2_analog_high)
• Adjustment to ensure solar background from AD and PC data are identical for the
  high nitrogen channel(solar_offset_nudge_nh)
• Mean electronic background subtracted from the low channel elastic analog signal(electronic_background_elastic_analog_low)
• Fit parameters for the high temperature #1 channel(parameters_t1_high)
• Adjustment to ensure solar background from AD and PC data are identical for the
  low nitrogen channel(solar_offset_nudge_nl)
• Solar background in the low channel nitrogen channel(solar_background_nitrogen_low)
• Glue coefficient (offset) for low elastic channel(elastic_counts_low_glue_coef_offset)
• Glue coefficient (slope) for high temperature #2 channel(t2_counts_high_glue_coef_slope)
• Fit parameters for the high temperature #2 channel(parameters_t2_high)
• Glue coefficient (slope) for high nitrogen channel(nitrogen_counts_high_glue_coef_slope)
• Glue coefficient (offset) for high temperature #1 channel(t1_counts_high_glue_coef_offset)
• Number of photons counted in the temperature 2 channel(t2_counts_high)
• Number of photons counted in the low water vapor channel(water_counts_low)
• Mean electronic background subtracted from the high channel depolarization
  analog signal(electronic_background_depolarization_analog_high)
• Glue coefficient (slope) for high water vapor channel(water_counts_high_glue_coef_slope)
• Glue coefficient (slope) for high temperature #1 channel(t1_counts_high_glue_coef_slope)
• Number of lidar pulses summed(shots_summed)
• Glue coefficient (slope) for high depolarization channel(depolarization_counts_high_glue_coef_slope)
• Glue coefficient (offset) for high elastic channel(elastic_counts_high_glue_coef_offset)
• Glue coefficient (offset) for high temperature #2 channel(t2_counts_high_glue_coef_offset)
• Solar background in the low channel elastic channel(solar_background_elastic_low)
• Adjustment to ensure solar background from AD and PC data are identical for the
  high temperature #1 channel(solar_offset_nudge_t1)
• Fit parameters for the high depolarization channel(parameters_depolarization_high)
• Adjustment to ensure solar background from AD and PC data are identical for the
  high temperature #2 channel(solar_offset_nudge_t2)
• Parameters associated with the fit of the analog and photon counting data(parameters)
• Mean electronic background subtracted from the high channel liquid analog signal(electronic_background_liquid_analog_high)
• Glue coefficient (offset) for high liquid channel(liquid_counts_high_glue_coef_offset)
• Fit parameters for the low water vapor channel(parameters_water_low)
• Glue coefficient (slope) for low elastic channel(elastic_counts_low_glue_coef_slope)
• Binary flags indicating whether PC or analog data were used in the profile(merge_flags_high)
• Mean electronic background subtracted from the high channel nitrogen analog
  signal(electronic_background_nitrogen_analog_high)
• N2 cloud check value(n2_cloud_check_value)
• Number of photons counted in the low elastic (aerosol) channel(elastic_counts_low)
• Fit parameters for the low elastic channel(parameters_elastic_low)
• Mean electronic background subtracted from the low channel nitrogen analog
  signal(electronic_background_nitrogen_analog_low)
• Count rate in the high water vapor channel(water_counts_high)
• Fit parameters for the high elastic channel(parameters_elastic_high)
• Adjustment to ensure solar background from AD and PC data are identical for the
  high depolarization channel(solar_offset_nudge_dh)
• Number of photons counted in the high nitrogen channel(nitrogen_counts_high)
• Glue coefficient (slope) for high liquid channel(liquid_counts_high_glue_coef_slope)
• Glue coefficient (offset) for high depolarization channel(depolarization_counts_high_glue_coef_offset)
• Adjustment to ensure solar background from AD and PC data are identical for the
  high elastic channel(solar_offset_nudge_eh)
• Adjustment to ensure solar background from AD and PC data are identical for the
  low elastic channel(solar_offset_nudge_el)
• Adjustment to ensure solar background from AD and PC data are identical for the
  low water vapor channel(solar_offset_nudge_wl)
• Binary flags indicating whether PC or analog data were used in the profile(merge_flags_low)
• Number of photons counted in the temperature 1 channel(t1_counts_high)
• Adjustment to ensure solar background from AD and PC data are identical for the
  high water vapor channel(solar_offset_nudge_wh)
• Fit parameters for the high water vapor channel(parameters_water_high)
• Cloud value check flag(cloud_value_check)
• Glue coefficient (slope) for low nitrogen channel(nitrogen_counts_low_glue_coef_slope)
• Mean electronic background subtracted from the high channel elastic analog
  signal(electronic_background_elastic_analog_high)
• Number of photons counted in the low nitrogen channel(nitrogen_counts_low)
• Solar background in the low channel water channel(solar_background_water_low)
• Fit parameters for the high liquid channel(parameters_liquid_high)
• Count rate in the high depolarization channel(depolarization_counts_high)

• Aerosol scattering ratio profile created by merging the two Calibrated channels(cal_asr_1)
• Scale factor added to the low aerosol scattering ratio at each time sample(scale_add_lo)
• Vertical scale factor for statistical T-test sanity check on high channel data(vert_scale_hi_2)
• Uncertainty of the Calibrated aerosol scattering ratio profile from the low
  channel(cal_asr_error_low)
• Uncertainty of the aerosol scattering ratio profile from the high channel(asr_error_high)
• Calibration factor applied to the low aerosol scattering ratio at each time
  sample(cal_factor_lo)
• Calibrated Aerosol scattering ratio profile from the low channel(cal_asr_low)
• Aerosol backscatter coefficient uncertainty(bscat_err)
• Scale factor added to the high aerosol scattering ratio at each time sample and
  height(scale_add_hi)
• Aerosol scattering ratio profile from the low channel(asr_low)
• Differential transmission correction for aerosols(diff_trans_aerosol_corr)
• Type of calibration used to compute the high channel calibration at each time
  interval(hi_cal_type)
• Uncertainty of the aerosol scattering ratio profile created by merging the two
  channels(asr_1_error)
• Flag denoting the occurrence of power or alignment tweaks(tweaks)
• Vertical scale factor to make shape of high channel profile match low channel(vert_scale_hi)
• Uncertainty of the aerosol scattering ratio profile created by merging the two
  Calibrated channels(cal_asr_1_error)
• Number of lidar pulses summed(shots_summed)
• Aerosol scattering ratio profile created by merging the two channels(asr_1)
• Calibrated Aerosol scattering ratio profile from the high channel(cal_asr_high)
• Uncertainty of the Calibrated aerosol scattering ratio profile from the high
  channel(cal_asr_error_high)
• Uncertainty of the aerosol scattering ratio profile from the low channel(asr_error_low)
• Cloud mask(cloud_mask)
• Aerosol scattering ratio profile from the high channel(asr_high)
• Scale factor added to the high aerosol scattering ratio at each time sample and
  height (2nd iteration)(scale_add_hi_2)
• Corrected Aerosol volume backscattering coefficient at 355 nm - removed negative
  vals(corr_bscat)
• Calibration factor applied to the high aerosol scattering ratio at each time
  sample(cal_factor_hi)

• Water vapor mixing ratio profile from the low channel(mixing_ratio_low)
• Vertical resolution of bright mode (mode == 2) data(vertical_resolution_bright_mode)
• Uncertainty of the water vapor mixing ratio profile created by merging the two
  channels(mixing_ratio_1_error)
• Random error in the precipitable water vapor observed by the Raman lidar(pwv_rl_err)
• Water vapor mixing ratio profile created by merging the two calibrated channels
  together with the surface in-situ measurements(mixing_ratio_3)
• Water vapor mixing ratio profile created by merging the two calibrated channels(mixing_ratio_2)
• Uncertainty of the water vapor mixing ratio profile created by merging the two
  calibrated channels(mixing_ratio_2_error)
• Water vapor mixing ratio profile created by merging the two channels(mixing_ratio_1)
• Suggested maximum altitude to use the water vapor data from the Raman lidar(wv_rl_max_height)
• Water vapor mixing ratio profile from the high channel(mixing_ratio_high)
• Uncertainty of the water vapor mixing ratio profile from the high channel(mixing_ratio_error_high)
• Flag denoting the occurrence of power or alignment tweaks(tweaks)
• Calibration factor used to match the high channel mixing ratio to the low
  channel mixing ratio(calib_high_low)
• Number of lidar pulses summed(shots_summed)
• Uncertainty of the water vapor mixing ratio profile created by merging the two
  calibrated channels(mixing_ratio_3_error)
• Vertical resolution of normal mode (mode == 1) data(vertical_resolution_normal_mode)
• Calibration factor for entire profile(calib_factor)
• Relative humidity over ice calculated from the merged water vapor mixing ratio
  data(relative_humidity_over_ice)
• Relative humidity calculated from the merged water vapor mixing ratio data(relative_humidity)
• Differential transmission correction for aerosols(diff_trans_aerosol_corr)
• Fraction of the total precipitable water vapor in the column sensed by the Raman
  lidar(pwv_rl_fraction)
• Uncertainty of the water vapor mixing ratio profile from the low channel(mixing_ratio_error_low)
• Precipitable water vapor observed by the Raman lidar(pwv_rl)

• Summed analog signal in the liquid water channel(liquid_analog_high)
• Number of photons counted in the liquid water channel(liquid_counts_high)
• Number of photons counted in the high nitrogen channel(nitrogen_counts_high)
• Number of laser shots recorded for the low elastic channel(shots_summed_elastic_low)
• Number of laser shots recorded for the low water channel(shots_summed_water_low)
• Number of photons counted in the temperature 2 channel(t2_counts_high)
• Summed analog signal in the temperature 1 channel(t1_analog_high)
• Summed analog signal in the high depolarization channel(depolarization_analog_high)
• Count rate in the high depolarization channel(depolarization_counts_high)
• Count rate in the high water vapor channel(water_counts_high)
• Summed analog signal in the low elastic channel(elastic_analog_low)
• Number of laser shots recorded for the high depolarization channel(shots_summed_depolarization_high)
• Number of laser shots recorded for the temperature 2 channel(shots_summed_t2_high)
• Number of laser shots recorded for the high elastic channel(shots_summed_elastic_high)
• Summed analog signal in the high water vapor channel(water_analog_high)
• Number of laser shots recorded for the high nitrogen channel(shots_summed_nitrogen_high)
• Number of laser shots recorded for the liquid water channel(shots_summed_liquid_high)
• Number of photons counted in the high elastic (aerosol) channel(elastic_counts_high)
• Number of laser shots recorded for the temperature 1 channel(shots_summed_t1_high)
• Number of laser shots recorded for the high water channel(shots_summed_water_high)
• Summed analog signal in the high elastic channel(elastic_analog_high)
• Number of photons counted in the low elastic (aerosol) channel(elastic_counts_low)
• Summed analog signal in the temperature 2 channel(t2_analog_high)
• Number of photons counted in the low water vapor channel(water_counts_low)
• Number of photons counted in the temperature 1 channel(t1_counts_high)
• Number of lidar pulses summed(shots_summed)
• Number of photons counted in the low nitrogen channel(nitrogen_counts_low)
• Summed analog signal in the low nitrogen channel(nitrogen_analog_low)
• N2 cloud check value(n2_cloud_check_value)
• Summed analog signal in the high nitrogen channel(nitrogen_analog_high)
• Cloud value check flag(cloud_value_check)
• Summed analog signal in the low water vapor channel(water_analog_low)
• Number of laser shots recorded for the low nitrogen channel(shots_summed_nitrogen_low)

• Cloud base height (for first cloud above height threshold)(cloud_base_height)
• Linear depolarization ratio profile(depolarization_ratio)
• Cloud depth(cloud_depth)
• Cloud attenuation flag(attenuation_flag)
• Flag denoting the occurrence of power or alignment tweaks(tweaks)
• Altitude of cloud top used in retrieval(cloud_top_height)
• Depolarization calibration factor(calibration_factor)
• Number of lidar pulses summed(shots_summed)
• Cloud optical thickness computed from aerosol (elastic) data(cloud_optical_thickness_aer)
• Cloud optical thickness computed from nitrogen data(cloud_optical_thickness_n2)
• Uncertainty of the linear depolarization ratio profile(depolarization_ratio_error)
• Cloud mask(cloud_mask)