SGP/RL/C1 - Incorrect time array

On March 27 2011 at 0100 GMT the Raman lidar's instrument computer automatically advanced 
it's time by one hour (transition to daylight savings time). The problem was eventually 
fixed on March 29 2011 at 1300 when the clock was set back one hour to the correct time. 
The ingest experienced problems when the clock was set back one hour.

The time arrays in the following files are set one hour ahead of what they should be:

1. sgprlC1.a0.20110327.000001.cdf for profile indices equal to or greater than 355
2. all of sgprlC1.a0.20110327.120001.cdf
3. all of sgprlC1.a0.20110328.134549.cdf
4. all of sgprlC1.a0.20110329.000005.cdf
5. sgprlC1.a0.20110329.120005.cdf for profile indices less than or equal to 72 

Also, the time arrays in sgprlC1.a0.20110329.120005.cdf between profile indices 73 through 
641 are incorrect. In this case, the offset varies approximately linearly with profile 
index from 1 hour at index 73 to 0 at index 641. The ingest apparently introduced some 
unphysical variations in time in this part of the file.

• time
• time_offset
• base_time

SGP/RL/C1 - Malfunction in WFOV data acquisition

A malfunction in the data acquisition hardware resulted in corrupted data in the 
wide-field-of-view (WFOV) nitrogen, water vapor and elastic channels. The problem is so serious as 
to yield these signals useless during the period covered by this DQR.

Do not use any data products derived from the WFOV raw signals during the period covered 
by this DQR. This includes water vapor mixing ratio, aerosol scattering ratio, and aerosol 
extinction. 

The narrow-field-of-view (NFOV)channels are unaffected by this problem. So data products 
derived from only the NFOV channel should be okay. These include the 'high' channel 
signals from the merge VAP, depolarization and temperature.

• elastic_counts_low_glue_coef_slope
• parameters_elastic_low
• parameters_nitrogen_low
• nitrogen_counts_low_glue_coef_slope
• water_counts_low_glue_coef_slope
• parameters_water_low
• nitrogen_counts_low_glue_coef_offset
• elastic_counts_low_glue_coef_offset
• water_counts_low_glue_coef_offset
• Raman backscatter, number of photons counted in the low nitrogen channel(nitrogen_counts_low)
• water_counts_low
• elastic_counts_low

SGP/RL/C1 - Frequent intermittent drop-outs in the WFOV photon counting signals

Beginning suddenly, near 1330 UTC on 31 May 2011, the liquid water and all three WFOV 
channels began showing intermittent and frequent “drop-outs” in the photon counting signals. 
These drop-outs were periods when the signal would momentarily fade and then come back. 

This problem, which was traced to a malfunction of the Licel data recorders, occurred at 
irregular intervals and with such frequency as to render the data from the affected 
channels useless. This problem persisted until repairs were made to the Licel transient 
recorders on 19 August 2011. 

Although only the WFOV channels (and liquid water channel) were affected, the aerosol and 
water vapor mixing ratio VAPs are computed by combining NFOV and WFOV channels. Thus, all 
of these higher level data products were adversely impacted by the drop-out problem.

The NFOV data in the sgprlC1.a0 and sgprlprofmerge1turnC1.c0 datastreams were unaffected 
by the "drop-out" problem. These signals could be used to compute aerosol optical 
properties and water vapor mixing ratio.

• solar_offset_nudge_lw
• liquid_counts_high
• solar_offset_nudge_wl
• electronic_background_elastic_analog_low
• parameters_elastic_low
• solar_background_nitrogen_low
• water_counts_low_glue_coef_offset
• electronic_background_water_analog_low
• elastic_counts_low_glue_coef_slope
• electronic_background_nitrogen_analog_low
• liquid_counts_high_glue_coef_offset
• solar_offset_nudge_el
• nitrogen_counts_low_glue_coef_slope
• solar_background_water_low
• parameters_nitrogen_low
• water_counts_low_glue_coef_slope
• elastic_counts_low_glue_coef_offset
• parameters_water_low
• nitrogen_counts_low_glue_coef_offset
• solar_offset_nudge_nl
• water_counts_low
• Raman backscatter, number of photons counted in the low nitrogen channel(nitrogen_counts_low)
• solar_background_elastic_low
• elastic_counts_low
• liquid_counts_high_glue_coef_slope

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.

• solar_offset_nudge_t2
• electronic_background_t1_analog_high
• Cloud base height(cbh)
• parameters
• solar_background_nitrogen_low
• solar_offset_nudge_t1
• electronic_background_t2_analog_high
• Raman backscatter, number of photons counted in the high nitrogen channel(nitrogen_counts_high)
• shots_summed
• electronic_background_depolarization_analog_high
• nitrogen_counts_low_glue_coef_slope
• solar_background_water_low
• parameters_water_low
• solar_offset_nudge_nl
• water_counts_high_glue_coef_slope
• t2_counts_high_glue_coef_offset
• elastic_counts_low
• solar_offset_nudge_nh
• solar_offset_nudge_wl
• electronic_background_elastic_analog_low
• parameters_t1_high
• parameters_nitrogen_high
• t1_counts_high_glue_coef_offset
• solar_offset_nudge_eh
• electronic_background_water_analog_high
• t1_counts_high_glue_coef_slope
• solar_offset_nudge_el
• solar_offset_nudge_wh
• nitrogen_counts_low_glue_coef_offset
• solar_background_elastic_low
• elastic_counts_high
• electronic_background_elastic_analog_high
• depolarization_counts_high_glue_coef_slope
• electronic_background_liquid_analog_high
• parameters_elastic_low
• parameters_elastic_high
• parameters_t2_high
• water_counts_low_glue_coef_offset
• elastic_counts_high_glue_coef_slope
• elastic_counts_low_glue_coef_slope
• electronic_background_nitrogen_analog_low
• water_counts_high
• water_counts_low_glue_coef_slope
• depolarization_counts_high_glue_coef_offset
• solar_offset_nudge_dh
• nitrogen_counts_high_glue_coef_slope
• liquid_counts_high_glue_coef_slope
• solar_offset_nudge_lw
• electronic_background_nitrogen_analog_high
• parameters_water_high
• t1_counts_high
• liquid_counts_high
• t2_counts_high_glue_coef_slope
• cloud_value_check
• depolarization_counts_high
• elastic_counts_high_glue_coef_offset
• nitrogen_counts_high_glue_coef_offset
• electronic_background_water_analog_low
• merge_flags_low
• n2_cloud_check_value
• liquid_counts_high_glue_coef_offset
• water_counts_high_glue_coef_offset
• parameters_nitrogen_low
• elastic_counts_low_glue_coef_offset
• merge_flags_high
• water_counts_low
• parameters_liquid_high
• parameters_depolarization_high
• Raman backscatter, number of photons counted in the low nitrogen channel(nitrogen_counts_low)
• t2_counts_high