NSA/MPL/C1 - laser head failure

On 2002-04-28 the laser energy was observed to decrease throughout the day.  Although low 
clouds continued to be detected, by the end of the day the output laser energy was about 
10% of nomimal.  This decrease continued throughout 2002-04-29 to the extent that clouds 
were no longer detected.  The source of failure was eventually determined to be the laser 
head, requiring the MPL to be shipped for repair.  The MPL was reinstalled on 2002-08-28 
at about 01:00 UTC.  

MPL NSA data from 2002-04-29 through 2002-08-27 (inclusive) should not be used.

• MPL Cloth et al. Algorithm Significance Mask(SigniMaskMplCloth)
• Height of Center of Each Range Bin(Heights)
• base time(base_time)
• Time offset of tweaks from base_time(time_offset)

• null(Raw data stream - documentation not supported)

• Height of Center of Each Range Bin(Heights)
• MPL Cloth et al. Algorithm Cloud Mask(CloudMaskMplCloth)
• Time offset of tweaks from base_time(time_offset)
• base time(base_time)

• Angle of orientation with respect to true geographic north(transceiver_azimuth_angle)
• Amount of time the actual laser pulse lags behind the sync trigger(laser_sync_offset)
• Number of laser shots recorded(shots_summed)
• base time(base_time)
• Background Signal(background_signal)
• Amount of time the scalar lags behind the sync trigger(scalar_sync_offset)
• Aerosol backscatter coefficient at 355 nm(backscatter)
• required to correct raw counts for detector deadtime prior to all other
  corrections.(deadtime_correction)
• Maximum altitude retrieved from multichannel scalar card.(max_altitude)
• Laser Temperature(laser_temp)
• Number of laser pulses summed during measurement interval(shots_sum)
• Distance from leading edge of first range bin to the center of each bin .(range_bins)
• Preliminary cloud base height(preliminary_cbh)
• Voltage level which operates the A/D card and the detector(voltage_05)
• value represents date of last configuration change as yyyymmdd(property)
• Array of heights for the range gates(height)
• time(time)
• lat(lat)
• Repetition rate, or Trigger Frequency of the laser(trigger_freq)
• Time in nanoseconds for each range bin of multichannel scalar card.(range_bin_time)
• Time offset of tweaks from base_time(time_offset)
• effective range offset due to poor sync between laser firing and A/D trigger.(range_offset)
• Detector Temperature(detector_temp)
• Dummy altitude for Zeb(alt)
• Voltage level which operates the energy monitor(voltage_15)
• Sum of raw backscatter counts per bin prior to ANY corrections.(total_counts)
• Voltage level which operates the thermistor(voltage_10)
• Amount of time laser pulse lags behind the scalar trigger(laser_scalar_sync_offset)
• Filter Temperature(filter_temp)
• Instrument Temperature(instrument_temp)
• Width of range-bins calculated from range_bin_time(range_bin_width)
• Repetition Rate, or Trigger Frequency of the laser(pulse_rep)
• lon(lon)
• Laser output energy per pulse(energy_monitor)
• Angle of inclination with respect to horizontal(transceiver_altitude_angle)
• range(range)