I’ll be using this thread to store information about maintenance to the NWTC M4 (Site 4.4) met tower.
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November 15-19, 2013: DAS failure.
The M4 DAS failed on Friday 15 November. The system has been rebuilt and was restarted at approximately 21:20 UTC on November 19.
December 10, 17:00 UTC
The 131 m sonic on M4 appears to be failing. We’re seeing loss of data on the z axis and from the temperature. These two channels are interdependent in the sonic’s internal data processing. We’re looking into replacing the sonic as time and manpower allows.
The 131 m sonic has been replaced. Data are available from approximately 16:00 UTC on March 21, 2014.
September 2 through September 5, 2014
We’re in the process of doing our annual swap of instruments on the M4 tower. This started on the morning of September 2 (approximately midday UTC of September 2). We expect this to take until Friday. Depending on the weather, it may be quicker. We’ll leave the Data Acquisition System off for this period and restart the system with the new calibration coefficients. Users shouldn’t see any impact other than the 4 days of missing data.
The M4 10-m cup was giving bad signals during the period September 4-11, 2014. We’ve isolated this to a problem with the cup pulses not being strong enough to register with the DAS, so we weren’t getting frequency signal and thus couldn’t get the wind speed. It looks like this error was being detected by the data processing software, but I will flag the data in the next few days. We’ve now changed the wiring on this sensor so that the pulses are more reliable. Users should not see any more problems (with luck).
The M4 DAS failed on December 5 and was restarted on December 14. Approximately 8 days of data have been lost.
Data processing routines have been updated to work with the new DAS on the M5 tower, so you will see M4 data with version 1.4 in the next few days. The M4 tower is still operating on the previous DAS, however.
The new M4 DAS went live on February 21 and we have completed in-house testing. The new DAS has the same features as the DAS on M5:
- Raw data are written using an XML-based format, called labview TDMS. we do all the conversion for you, so you will see no change to the raw data on the web server.
- Sonic anemometers and accelerometers run at 20 Hz. All other sensors run at 1 Hz, but data are still written to file at 20 Hz. You will see this in the raw data on the server. You will have to downsample the 20-Hz data in the file to 1 Hz before calculating statistics.
New M4 data are now streaming to the archives and being displayed on the main M4 page at nwtc.nrel.gov/m4.