ENA/CCN/C1 - Problem with time fields

During the ENA deployment the CCN instrument clock was not synched with a time server 
until 12/2/2014.  Starting at about 11/03/2013 the CCN was 60 seconds slow.  From that time 
until the time was manually corrected on 10/07/2014 at 16:00:00 the CCN time gradually got 
faster relative to the CPC until it was approximately 10 minutes fast. On 12/2/2014 at 
20:28:30 the CCN was configured to automatically correct its time from the Unit 1 CPU.  
Since that time the CCN has been within 2 seconds of the time server except at startup.  
More recently the setting was changed to keep the CCN within about .6 sec.  Generally the 
time is being corrected by time client about once every 3 days.  

There have been 2 startups since the time synching was configured.  At these times the 
time was off by more, but was immediately corrected.  On 12/30/2014 at 19:28:01 the time was 
fast 66.235 sec. at startup.  On 01/16/2015 the time was fast 38.512 sec. at startup.

The  Document  shows the times of the peaks used to approximate the 
error in the time. The time was checked about once a week and its assumed that the time 
drifted gradually between the times in the file.

Average data for longer periods.

Compare peaks with other instruments to calculate how far off the time was.




null

• Time offset from base_time(time_offset)
• lon(lon)
• First stage monitor voltage(CCN_first_stage_monitor_voltage)
• AOS CCN volumetric flowrate of sheath air(CCN_Q_sheath)
• base time in epoch(base_time)
• Standard deviation of CCN temperature gradient (CCN_t_read_TEC3 -
  CCN_t_read_TEC1)(CCN_temperature_std)
• CCN Proportional valve voltage(CCN_proportional_valve_voltage)
• AOS CCN sample saturation setpoint value reported by instrument(CCN_ss_set)
• Bin number of lowest channel of OPC include in summation of N_CCN(N_CCN_bin_number)
• Temperature difference between CCN_t_set_TEC3 and CCN_t_set_TEC1(CCN_temperature_gradient)
• Cloud condensation nuclei number density(N_CCN)
• AOS CCN temperature of sample air at entrance to instrument(CCN_T_inlet)
• AOS CCN observed temperature at middle of column(CCN_t_read_TEC2)
• AOS CCN observed temperature at top of column(CCN_t_read_TEC1)
• AOS CCN OPC laser current(CCN_laser_current)
• AOS CCN (read) temperature at bottom of column(CCN_t_read_TEC3)
• AOS CCN sample pressure(CCN_P_sample)
• -180.0 - +180.0(alt)
• AOS CCN volumetric flowrate of sample air(CCN_Q_sample)
• time_in_seconds_since_volume_start(time)
• AOS CCN temperature of the optical particle counter(CCN_T_OPC)
• AOS CCN temperature of sample air entering the column(CCN_T_sample)
• North Latitude(lat)
• AOS CCN temperature of the nafion humidifier(CCN_T_nafion)
• AOS CCN number concentration by bin(N_CCN_dN)
• AOS CCN logical value, indicating whether the instrument has reached thermal
  gradient stabilization and is within 0.4 degrees C of the set point(CCN_temp_unstable_flag)
• AOS CCN super saturation (calculated)(CCN_super_saturation_calculated)