TWP/MPL/C1 - SunShade timing problem

For an unknown reason, the sun shade was dropping for less then 10 minutes during the 
night at about 19:00 UTC between Dec 14, 2003 and Feb 17, 2004.  Data taken during that ten 
minute interval is not looking at the sky and should be considered as though it were 
missing.

This is a fairly small effect.  Data users can simply average across the interval or block 
the records as "missing".

• Laser temperature(laser_temp)
• Aerosol volume backscattering coefficient at 355 nm(backscatter)
• Filter temperature(filter_temp)
• Background signal(background_signal)
• Detector temperature(detector_temp)
• altitude above sea levelaltunits(alt)
• GPS raw data filename(filename)
• east longitude for all the input platforms.(lon)
• Time offset of tweaks from base_time(time_offset)
• Voltage level which operates the A_D card and the detector(voltage_5)
• Voltage level which operates the thermistor(voltage_10)
• Average cloud base height used in the retrieval(cbh)
• Number of laser pulses summed during measurement interval(shots_summed)
• Instrument temperature(instrument_temp)
• Repetition rate, or Trigger Frequency of the laser(pulse_rep)
• Time offset from base_time(base_time)
• Energy output per pulse of transmitted laser beam at 532 nm (Doubled Nd -YLF)(energy_monitor)
• Voltage level which operates the energy monitor(voltage_15)
• north latitude for all the input platforms.(lat)

• Raw data stream - documentation not supported(Raw data stream - documentation not supported)

• Range Heights (center of radar sample volume)(Heights)
• MPL Cloth et al. Algorithm Significance Mask(SigniMaskMplCloth)
• Time offset of tweaks from base_time(time_offset)
• Time offset from base_time(base_time)

• Time offset from base_time(base_time)
• Time offset of tweaks from base_time(time_offset)
• Range Heights (center of radar sample volume)(Heights)
• MPL Clothiaux et al. Algorithm Cloud Mask Occurrence(CloudMaskMplCloth)

TWP/MPL/C1 - SP laser diode supply failed

The Spectra Physics laser diode supply failed on March 2, 2004.  A replacement was 
installed April 18. 

Any data between these dates is worthless.

• Laser temperature(laser_temp)
• Aerosol volume backscattering coefficient at 355 nm(backscatter)
• Filter temperature(filter_temp)
• Background signal(background_signal)
• Detector temperature(detector_temp)
• altitude above sea levelaltunits(alt)
• GPS raw data filename(filename)
• east longitude for all the input platforms.(lon)
• Time offset of tweaks from base_time(time_offset)
• Voltage level which operates the A_D card and the detector(voltage_5)
• Voltage level which operates the thermistor(voltage_10)
• Average cloud base height used in the retrieval(cbh)
• Number of laser pulses summed during measurement interval(shots_summed)
• Instrument temperature(instrument_temp)
• Repetition rate, or Trigger Frequency of the laser(pulse_rep)
• Time offset from base_time(base_time)
• Energy output per pulse of transmitted laser beam at 532 nm (Doubled Nd -YLF)(energy_monitor)
• Voltage level which operates the energy monitor(voltage_15)
• north latitude for all the input platforms.(lat)

• Raw data stream - documentation not supported(Raw data stream - documentation not supported)

• Range Heights (center of radar sample volume)(Heights)
• MPL Cloth et al. Algorithm Significance Mask(SigniMaskMplCloth)
• Time offset of tweaks from base_time(time_offset)
• Time offset from base_time(base_time)

• Time offset from base_time(base_time)
• Time offset of tweaks from base_time(time_offset)
• Range Heights (center of radar sample volume)(Heights)
• MPL Clothiaux et al. Algorithm Cloud Mask Occurrence(CloudMaskMplCloth)

TWP/MPL/C1 - energy monitor spikes

The energy monitor spiked to abnormal values, from 2 up to 25 microjoules per pulse. At 
the beginning, it was only a few intermittent spikes, but the spikes became more frequent. 
Most of June does not show a spiky energy monitor. On June 28-30, July 1-10 a diurnal 
pattern shows up. On July 12-13 it abruptly goes away and returns July 14-16 for 24hrs. Then 
abruptly stops again 17-19. Except for the 12th, the last changes occurred at 00:00 UTC 
suggesting a piece of equipment is turning on and off. I do not know why a noisy energy 
monitor would have a day/night or 00:00UTC dependence.

• Energy output per pulse of transmitted laser beam at 532 nm (Doubled Nd -YLF)(energy_monitor)

• Raw data stream - documentation not supported(Raw data stream - documentation not supported)

TWP/MPL/C1 - Energy monitor values are erroneous

Energy monitor values should not be used to normalization the backscatter profiles. A 
problem with the energy monitor electronics forced the value to maximum. The problem was 
corrected.

• Energy output per pulse of transmitted laser beam at 532 nm (Doubled Nd -YLF)(energy_monitor)

• Raw data stream - documentation not supported(Raw data stream - documentation not supported)

TWP/MPL/C1 - Time stamps are incorrect.

The computer was experiencing time synchronization problems. The time stamp for the data 
is incorrect. The synchronization continued to get worse throughout the period.  Secondary 
results of the sync problem are data gaps. The problem exhibited itself with data gaps 
at the end of every hour. As the computer continued to get further out of sync, the 
duration of the data gaps increased.

The error in time synchronization can be corrected by comparing the MPL data with another 
instrument such as the ceilometers or MMCR. The error in time can be determined by 
looking for identical cloud structure. Then shift the MPL data in time to match the other 
instruments. Remember the error is not constant; it continues to get worst throughout the period.

• Laser temperature(laser_temp)
• Voltage level which operates the thermistor(voltage_10)
• Assumed zero-range bin number\(assumed_zero_range_bin)
• Number of laser pulses summed during measurement interval(shots_summed)
• Background signal(background_signal)
• Instrument temperature(instrument_temp)
• Filter temperature(filter_temp)
• Repetition rate, or Trigger Frequency of the laser(pulse_rep)
• effective range offset due to poor sync between laser firing and A/D trigger.(range_offset)
• Time offset from base_time(base_time)
• Detector temperature(detector_temp)
• Preliminary cloud base height above ground level(preliminary_cbh)
• Energy output per pulse of transmitted laser beam at 532 nm (Doubled Nd -YLF)(energy_monitor)
• Time offset from midnight of date of file. For CO data, this is identical to
  time_offset and is included for compatibility.(time)
• Voltage level which operates the energy monitor(voltage_15)
• Attenuated backscatter(detector_counts)
• Voltage level which operates the A/D card and the detector(voltage_05)
• Time in nanoseconds for each range bin of multichannel scalar card.(range_bin_time)
• Time offset of tweaks from base_time(time_offset)

• Raw data stream - documentation not supported(Raw data stream - documentation not supported)

TWP/MPL/C1 - Data dropouts

Data dropouts occurred during this period. Problem ended when MPL computer was rebooted.

• Background signal(background_signal)
• Angle of orientation with respect to true geographic north(tranceiver_azimuth_angle)
• distance to center of range bin after correcting for offset in sync(range)
• Height of bins above ground level for the temperature, retrieved water vapor,
  and pressure profile(height)
• Detector temperature(detector_temp)
• altitude above sea levelaltunits(alt)
• required to correct raw counts for detector deadtime prior to all other
  corrections.(deadtime_correction)
• Amount of time the actual laser pulse lags behind the sync trigger(laser_sync_offset)
• GPS raw data filename(filename)
• east longitude for all the input platforms.(lon)
• Attenuated backscatter(detector_counts)
• Maximum altitude retrieved from multichannel scalar card.(max_altitude)
• Voltage level which operates the thermistor(voltage_10)
• Average cloud base height used in the retrieval(cbh)
• Repetition rate, or Trigger Frequency of the laser(pulse_rep)
• Preliminary cloud base height above ground level(preliminary_cbh)
• Voltage level which operates the energy monitor(voltage_15)
• value represents date when configuration is first applicable as YYYYMMDD(property)
• north latitude for all the input platforms.(lat)
• Angle of inclination with respect to horizontal(tranceiver_altitude_angle)
• Number of laser pulses summed during measurement interval(shots_sum)
• Laser temperature(laser_temp)
• Aerosol volume backscattering coefficient at 355 nm(backscatter)
• Filter temperature(filter_temp)
• Time offset from midnight of date of file. For CO data, this is identical to
  time_offset and is included for compatibility.(time)
• 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)
• Repetition rate, or Trigger Frequency of the laser(trigger_freq)
• Time offset of tweaks from base_time(time_offset)
• Voltage level which operates the A_D card and the detector(voltage_5)
• Width of range-bins calculated from range_bin_time(range_bin_width)
• Assumed zero-range bin number\(assumed_zero_range_bin)
• Number of laser pulses summed during measurement interval(shots_summed)
• Instrument temperature(instrument_temp)
• effective range offset due to poor sync between laser firing and A/D trigger.(range_offset)
• Time offset from base_time(base_time)
• Energy output per pulse of transmitted laser beam at 532 nm (Doubled Nd -YLF)(energy_monitor)
• Amount of time the scalar lags behind the sync trigger(scalar_sync_offset)
• Amount of time laser pulse lags behind the scalar trigger(laser_scalar_sync_offset)
• Voltage level which operates the A/D card and the detector(voltage_05)
• Time in nanoseconds for each range bin of multichannel scalar card.(range_bin_time)

• Time offset of tweaks from base_time(time_offset)
• Range Heights (center of radar sample volume)(Heights)
• MPL Cloth et al. Algorithm Significance Mask(SigniMaskMplCloth)
• Time offset from base_time(base_time)

• Time offset from base_time(base_time)
• Time offset of tweaks from base_time(time_offset)
• Range Heights (center of radar sample volume)(Heights)
• MPL Clothiaux et al. Algorithm Cloud Mask Occurrence(CloudMaskMplCloth)