Users of the data from the 135-m met towers may have noticed that the sonic anemometer data were quite 'gappy' up to now. We had a problem where each 10-minute data file only contained 90-97% valid sonic data. This made the data very hard to use for any application where spectral or frequency information was required, or where a continuous data set was required.
Over the past year or more we've worked on the tower data acquisition system (DAS) and with the sonic anemometer manufacturer to isolate the problems. We've implemented improved bench testing of the sonics before deployment, and changed some of the tools we use to keep an eye on the data. We're confident that we're now installing better quality sonics and have a better overview of their performance.
As a result of these changes, we've just rolled out a new DAS to the M4 and M5 towers, and we now have good, continuous 20-Hz data acquisition with no obvious loss of data from the sonics.
This will affect the following data:
- M4: Files from 15:30 UTC on October 15 onward (file name 10153_15_30_00_026)
- M5: Files from 20:50 UTC on October 14 onward (filename 10143_20_50_00_013)
Data formats have not changed.