Continuing signal degradation

Despite recent efforts (970310-970314) by the instrument mentor, signal 
degradation of the MPL has continued.  The degradation has continued to the 
point that the effective range of the MPL is nearing 10 km.  The instrument mentor and PI 
have 
concluded that an overhaul of the instrument by the vendor is in order.

Circa 970415, the MPL at SGP will be returned to the vendor for overhaul.   
Meanwhile, at about the same time, it will be replaced with the MPL from 
ARCS2 with an identical data format and an improved energy monitor.  The 
serial number of the detector and applicable dead-time correction must be 
verified and recorded as this affects calibration of the data.

• Repetition Rate, or Trigger Frequency of the laser(pulse_rep)
• Voltage level which operates the energy monitor(voltage_15)
• base time in epoch(base_time)
• Detector Temperature(detector_temp)
• Number of laser pulses summed during measurement interval(shots_sum)
• Voltage level which operates the thermistor(voltage_10)
• Laser Temperature(laser_temp)
• Height(height)
• Filter Temperature(filter_temp)
• 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)
• Repetition rate, or Trigger Frequency of the laser(trigger_freq)
• Number of lidar pulses summed(shots_summed)
• 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)
• 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)
• 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 orientation with respect to true geographic north(transceiver_azimuth_angle)
• value represents earliest applicable date as yyyymmdd(property)
• -180.0 - +180.0(alt)
• Angle of inclination with respect to horizontal(transceiver_altitude_angle)
• Distance to the center of the corresponding range bin(range)
• Time offset from base_time(time_offset)
• time_in_seconds_since_volume_start(time)
• Maximum altitude retrieved from multichannel scalar card.(max_altitude)
• Preliminary cloud base height above ground level(preliminary_cbh)
• Instrument Temperature(instrument_temp)

• (Development raw data stream - documentation not supported)

• North Latitude(lat)
• Average cloud base height used in the retrieval(cbh)
• -180.0 - +180.0(alt)
• Time offset from base_time(time_offset)
• base time in epoch(base_time)
• lon(lon)