nominal time versus start time

[adokter]

Certain baltrad polar volumes have nominal time in 15 minute blocks, even when polar volumes are available every 5 minutes. This leads to profiles that have duplicate nominal times (under what/date and what/time). The starting time of the scan, as stored under /how/startdate attribute, is different for these polar volumes.

Two possible solutions:

1. switch to using /how/startdate or - more in line with bioRad convention so far - (/how/startdate + /how/enddate)/2as the profile nominal time instead. This requires a change in vol2bird.
2. make sure nonimal times are different for the polar scans on baltrad, which requires a change in baltrad polar volume generation.

[adokter]

Need to inquire with Gunther Haase whether this should be considered baltrad issue, this might happen in merging scripts generating polar volumes that do not store the adequate nominal time.

[adokter]

From ODIM hdf5 data model:

Note that all date and time information is for the nominal time of the data, ie. the time for which the data are valid. (The nominal time is not the exact acquisition time which is found elsewhere in the file.)

Note that all scans belonging to the same volume must have the same nominal date and time.

Some ambiguity here in what time for which the data are valid means exactly