DQRID : D110409.1
Start DateStart TimeEnd DateEnd Time Data Quality Metric
03/27/2011010003/29/20111300Incorrect
more
Subject:
SGP/RL/C1 - Incorrect time array
DataStreams:sgp10rlprofbe1turnC1.c0, sgp10rlprofdep1turnC1.c1, sgp10rlprofasr1ferrC1.c1,
sgp10rlprofbe1turnC1.c1, sgprlC1.a0, sgp10rlprofext1ferrC1.c1, sgp10rlprofmr1turnC1.c1,
sgprlprofmerge1turnC1.c0, sgprllogC1.a0
Description:
On March 27 2011 at 0100 GMT the Raman lidar's instrument computer automatically advanced 
it's time by one hour (transition to daylight savings time). The problem was eventually 
fixed on March 29 2011 at 1300 when the clock was set back one hour to the correct time. 
The ingest experienced problems when the clock was set back one hour.

The time arrays in the following files are set one hour ahead of what they should be:

1. sgprlC1.a0.20110327.000001.cdf for profile indices equal to or greater than 355
2. all of sgprlC1.a0.20110327.120001.cdf
3. all of sgprlC1.a0.20110328.134549.cdf
4. all of sgprlC1.a0.20110329.000005.cdf
5. sgprlC1.a0.20110329.120005.cdf for profile indices less than or equal to 72 

Also, the time arrays in sgprlC1.a0.20110329.120005.cdf between profile indices 73 through 
641 are incorrect. In this case, the offset varies approximately linearly with profile 
index from 1 hour at index 73 to 0 at index 641. The ingest apparently introduced some 
unphysical variations in time in this part of the file.
Suggestions: 
Users should subtract one hour from the time arrays in the following files:

1. 
sgpr
lC1.a0.20110327.000001.cdf for profile indices equal to or greater than 355
2. all of 
sgprlC1.a0.20110327.120001.cdf
3. all of sgprlC1.a0.20110328.134549.cdf
4. all of 
sgprlC1.a0.20110329.000005.cdf
5. sgprlC1.a0.20110329.120005.cdf for profile indices less than or equal to 72 

Between profile indices 73 through 641 in sgprlC1.a0.20110329.120005.cdf a reasonable approximation to the time arrays can be computed by linear interpolation (as a function of profile index) between the corrected time at index 72 and the reported time at index 642.
Measurements:sgprllogC1.a0:
  • base_time
  • time_offset
more
sgp10rlprofext1ferrC1.c1:
  • base_time
  • time_offset
more
sgprlprofmerge1turnC1.c0:
  • time
  • base_time
  • time_offset
more
sgp10rlprofasr1ferrC1.c1:
  • base_time
  • time_offset
more
sgp10rlprofmr1turnC1.c1:
  • time_offset
  • base_time
more
sgprlC1.a0:
  • time_offset
  • base_time
  • time
more
sgp10rlprofdep1turnC1.c1:
  • time_offset
more
sgp10rlprofbe1turnC1.c0:
  • base_time
more
sgp10rlprofbe1turnC1.c1:
  • time_offset
  • base_time
more

Close this window