SGP/MPL/C1 - Signal degrading

The MPL viewport window was blown off during a storm on 2002/09/25.  The MPL received a 
soaking of rain.  Following this event, although site operations cleaned and dried the 
optics, the lidar performance continued to degrade over the next few months.  Although 
initially suitable for cloud detection, by Dec 10th the lidar was providing useful results only 
during the day (oddly enough).  By Jan 16, the detector was dead.  

It is not recommended to depend on night-time cloud base heights after Dec. 10 2002. 

It is not recommended to use any of the data after 9/25 for aerosol retrievals.

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• Repetition Rate, or Trigger Frequency of the laser(pulse_rep)
• Voltage level which operates the energy monitor(voltage_15)
• Detector Temperature(detector_temp)
• Voltage level which operates the thermistor(voltage_10)
• Laser Temperature(laser_temp)
• Height(height)
• Filter Temperature(filter_temp)
• Repetition rate, or Trigger Frequency of the laser(trigger_freq)
• Laser output energy per pulse(energy_monitor)
• Background signal(background_signal)
• Deadtime correction factor(deadtime_correction)
• Amount of time laser pulse lags behind the scalar trigger(laser_scalar_sync_offset)
• Width of range-bins calculated from range_bin_time(range_bin_width)
• Amount of time the scalar lags behind the sync trigger(scalar_sync_offset)
• Sum of raw backscatter counts per bin prior to ANY corrections.(total_counts)
• Distance from leading edge of first range bin to the center of each bin .(range_bins)
• Angle of inclination with respect to horizontal(transceiver_altitude_angle)
• Time offset from base_time(time_offset)
• Maximum altitude retrieved from multichannel scalar card.(max_altitude)
• Preliminary cloud base height above ground level(preliminary_cbh)
• base time in epoch(base_time)
• Number of laser pulses summed during measurement interval(shots_sum)
• Subtract from range_bins to yield range(range_offset)
• Aerosol volume backscattering coefficient at 355 nm(backscatter)
• Time in nanoseconds for each range bin of multichannel scalar card.(range_bin_time)
• lon(lon)
• Number of lidar pulses summed(shots_summed)
• Voltage level which operates the A/D card and the detector(voltage_05)
• Amount of time the actual laser pulse lags behind the sync trigger(laser_sync_offset)
• North Latitude(lat)
• Angle of orientation with respect to true geographic north(transceiver_azimuth_angle)
• value represents earliest applicable date as yyyymmdd(property)
• -180.0 - +180.0(alt)
• Distance to the center of the corresponding range bin(range)
• time_in_seconds_since_volume_start(time)
• Instrument Temperature(instrument_temp)

• Number of lidar pulses summed(shots_summed)
• Flag indicating whether the beam was extinguished at indicated cloud top(cloud_top_attenuation_flag)
• Repetition Rate, or Trigger Frequency of the laser(pulse_rep)
• Laser output energy per pulse(energy_monitor)
• -180.0 - +180.0(alt)
• Detector Temperature(detector_temp)
• Altitude of cloud top used in retrieval(cloud_top_height)
• North Latitude(lat)
• Laser Temperature(laser_temp)
• lon(lon)
• Aerosol volume backscattering coefficient at 355 nm(backscatter)
• base time in epoch(base_time)
• The update time of the historical baseline used for the cloud boundary
  determination of this sample(baseline_update_time)
• Time offset from base_time(time_offset)
• Instrument Temperature(instrument_temp)
• Background signal(background_signal)
• Cloud base height (for first cloud above height threshold)(cloud_base_height)
• Relative random error in backscatter profiles(random_error)
• Cloud mask(cloud_mask_2)
• Cloud mask(cloud_mask_1)
• Height(height)