HFE/MET/M1 -  Wind Speed data contain offset due to induced voltage

The marine model of the RM Young wind sensor needs twisted pair shielded cable.  The 
manufacturer did not originally supply the pigtail with twisted pair shielded cable.  Use of 
twisted pair shielded cable for the rest of the cable run to the logger was also not 
specified.  This caused an induced voltage in the wind speed line from the wind direction 
excitation.  The induced voltage varied from sensor to sensor and probably changed anytime 
the cable was replaced or parts of the wind sensor were repaired or replaced. The induced 
voltage has been seen to vary from 0.15 m/s to as much as 1.08 m/s.

• wind_spd_arith_max
• Vector-averaged Wind Speed(wind_spd_vec_avg)
• wind_spd_arith_min
• wind_spd_arith_sd
• Wind speed, lower, 1-min avg(wind_spd_arith_avg)

HFE/MPL/M1 - Frosting/Condensation

On various days during the China deployment, condensation accumulated on the view port 
window of the MPL and compromised its capability to detect clouds.  This problem most often 
occurred during nighttime hours from May through early September.  

During the listed times, cloud retrievals and aerosol profiles should be considered 
doubtful or in error.

The dates/times of occurrence are:
16:00-23:59 GMT on 05/18
17:00-22:00 GMT on 05/23
20:00-22:00 GMT on 05/25
15:00-23:59 GMT on 06/07
17:00-23:59 GMT on 06/08
15:00-23:00 GMT on 06/09
14:00-18:00 GMT on 06/18
18:00-21:00 GMT on 06/21
14:00-16:00 GMT on 06/23
16:00-21:00 GMT on 06/27
17:00-20:00 GMT on 06/28
      22:00 GMT on 06/29
19:00-23:00 GMT on 06/30
13:30-22:30 GMT on 07/02
16:00-17:30 GMT on 07/03 
20:30-22:00 GMT on 07/03
21:30-22:30 GMT on 07/05
13:00-22:00 GMT on 07/06
17:00-18:00 GMT on 07/07
21:00-22:30 GMT on 07/07
16:00-23:59 GMT on 07/10
11:00-23:00 GMT on 07/11
18:00-23:00 GMT on 07/12
15:00-16:00 GMT on 07/13
18:00-23:59 GMT on 07/14
18:00-21:00 GMT on 07/15
17:30-23:00 GMT on 07/16
17:00-23:00 GMT on 07/17
13:00-23:30 GMT on 07/20
18:00-23:00 GMT on 07/24
21:00-23:00 GMT on 07/25
21:00-22:30 GMT on 07/27
12:00-23:59 GMT on 08/02
16:00-21:30 GMT on 08/03
16:00-23:00 GMT on 08/04
14:00-22:30 GMT on 08/05
19:00-23:00 GMT on 08/07
19:00-21:30 GMT on 08/08
15:00-23:30 GMT on 08/10
17:30-23:30 GMT on 08/12
14:00-15:00 GMT on 08/14
16:30-22:30 GMT on 08/14
21:30-22:30 GMT on 08/17
12:00-23:59 GMT on 08/18
12:00-13:30 GMT on 08/19
20:00-23:30 GMT on 08/19
15:00-23:59 GMT on 08/20
11:00-23:59 GMT on 08/22
11:00-23:30 GMT on 08/23
12:00-23:30 GMT on 08/25
13:00-23:30 GMT on 08/26
16:30-23:59 GMT on 08/27
17:00-23:00 GMT on 08/31
15:00-23:59 GMT on 09/01
15:00-20:00 GMT on 09/02
19:30-23:59 GMT on 09/05
16:30-22:30 GMT on 09/09
19:30-23:59 GMT on 09/12
20:30-23:59 GMT on 09/15
14:00-16:30 GMT on 09/16
19:00-23:59 GMT on 09/16
20:30-23:59 GMT on 10/29
22:00-23:59 GMT on 11/01
20:00-23:59 GMT on 11/23
00:00-02:00 GMT on 11/24

• range
• background_signal_std_cross_pol
• Attenuated backscatter, copol(signal_return_co_pol)
• Attenuated backscatter, cross pol(signal_return_cross_pol)
• range_offset
• range_bins
• energy_monitor
• aqc_signal_return_co_pol
• aqc_signal_return_cross_pol
• base_time
• background_signal_co_pol
• polarization_control_voltage_co_pol
• shots_per_sample
• lat
• max_altitude
• dead_time_corrected
• background_signal_cross_pol
• num_bins
• Preliminary cloud base height above ground level, cross-pol(preliminary_cbh_cross_pol)
• range_bin_width
• laser_temp
• nsamples_cross_pol_average
• scope_temp
• detector_temp
• polarization_control_voltage_cross_pol
• Pressure, associated geometric height, at altitude, NGM model output(height)
• time_offset
• nsamples_co_pol_average
• background_signal_std_co_pol
• lon
• time
• alt
• Preliminary cloud base height above ground level, co-pol(preliminary_cbh_co_pol)
• num_channels
• pulse_rep

• shots_per_sample
• num_channels
• dead_time_corrected
• range
• range_bin_width
• Attenuated backscatter, cross pol(signal_return_cross_pol)
• polarization_control_voltage_cross_pol
• detector_temp
• alt
• background_signal_cross_pol
• background_signal_std_co_pol
• Pressure, associated geometric height, at altitude, NGM model output(height)
• Preliminary cloud base height above ground level, co-pol(preliminary_cbh_co_pol)
• lon
• max_altitude
• aqc_signal_return_co_pol
• lat
• polarization_control_voltage_co_pol
• scope_temp
• time_offset
• background_signal_std_cross_pol
• pulse_rep
• background_signal_co_pol
• aqc_signal_return_cross_pol
• nsamples_co_pol_average
• num_bins
• Preliminary cloud base height above ground level, cross-pol(preliminary_cbh_cross_pol)
• nsamples_cross_pol_average
• range_bins
• energy_monitor
• time
• base_time
• Attenuated backscatter, copol(signal_return_co_pol)
• laser_temp
• range_offset

• range
• num_channels
• polarization_control
• num_bins
• scope_temp
• lon
• detector_temp
• shots_per_avg
• polarization_control_voltage
• alt
• pulse_rep
• Pressure, associated geometric height, at altitude, NGM model output(height)
• background_signal_std
• lat
• base_time
• energy_monitor
• range_bins
• max_altitude
• laser_temp
• Preliminary cloud base height above ground level(preliminary_cbh)
• signal_return
• range_bin_width
• time
• time_offset
• range_offset
• background_signal
• range_bin_time
• dead_time_corrected

HFE/MET/M1 - Intermittent barometer failure

Intermittent barometer failure occurred throughout the deployment.  We were unable to 
pinpoint the cause of the failure.  Typically one or two minutes of missing data occurred 
every few days.

Since pressure data is typically invariant over 1 minute, linear interpolation should be 
fine to fill in missing data.

• Atmospheric pressure(atmos_pressure)

HFE/MET/M1 - Intermittent PWD data

The Present Weather Detector had intermittent missing values throughout this deployment.  
Missing values occurred almost everyday, usually just one or two minutes per day.

• pwd_cumul_snow
• Average 10 min visibility(pwd_avg_vis_10_min)
• pwd_pw_code_15_min
• pwd_id
• pwd_err_code
• Average 1 min visibility(pwd_avg_vis_1_min)
• pwd_pw_code_1_hr
• pwd_avg_H2O_int_1_min
• pwd_pw_code_inst
• pwd_cumul_water

HFE/MET/M1 - ORG Measuring Ice Crystals or Fog

The ORG was measuring consistent values for long periods of time.  Typically this is 
indicative of fog, ice crystals in the air or poor performance of the lens heaters.

• precip_rate_sd
• Rain, surface, 1-min avg(precip_rate_mean)
• precip_rate_max
• precip_rate_min

HFE/MET/M1 - Induced voltage on wind speed sensor cable

The cable for the wind monitor is not a twisted pair shielded cable.  This caused an 
induced voltage on the wind sensor wires from the wind direction measurement excitation 
voltage.  A small offset is added into the wind speeds.  This value varies.  Most frequently 
the values of 0.49, 0.588 and 0.686 m/s were added into the wind speed.  On 11/27/2008 the 
value jumped to 0.98 m/s for most of the day.

• wind_spd_arith_max
• Vector-averaged Wind Speed(wind_spd_vec_avg)
• wind_spd_arith_min
• wind_spd_arith_sd
• Wind speed, lower, 1-min avg(wind_spd_arith_avg)

HFE/VCEIL/M1 - Reprocess: Incorrect serial_number and sum_backscatter fields

Attribute serial_number: In most cases, this field is not representative of the actual 
serial number of the instrument because the value did not change when an instrument changed 
locations or was replaced with a spare.
   
Variable sum_backscatter: An out-of-range condition for the "sum of detected and 
normalized backscatter" was reported as 0 instead of missing (-9999). The valid range is 0 - 
0.0999 /srad.

• sum_backscatter

HFE/MET/M1 - Reprocess: ORG Data has very small rainrate values

The ORG data is collected via analog signal and not digital.  Therefore, we continuously 
collect data even when no rain is occurring.  We also capture small events such as leaves, 
large bugs, dust, etc blowing through the measurement path.  Because this discrete event 
occurs quickly the value is usually captured for 1 or 2 seconds.  This value is then 
averaged to the minute producing rainrate on the order of .009 mm/hr or less.  

These values are not indicative of rain and should be removed from the record or summing 
over long periods can bias the climate record.  We will reprocess the data to remove these 
small values.

• precip_rate_sd
• Rain, surface, 1-min avg(precip_rate_mean)
• precip_rate_max
• precip_rate_min