Blog from April, 2011

Arrived:  10:30am MDT

Departed: 11:20am MDT

Kurt and I installed three LiCors on turbulence tower at heights of 2M, 15M and 45M.  TRHs were installed on all levels. New GPS was added and old Garmin was removed.

LiCor heights:

2M-1166

15M-1163

45M-1164

Apr 12, 11:32 am

The output format and reporting rate of the 3 Licor 7500s that were re-installed today had been reset during the calibration procedure to generate verbose output, with labels. To save archive space, we configure the units for a terse output, without labels, at 10 Hz.

To setup the Licors for the format that our data system expects, do the following from the data system login prompt:

1. shut down the data process
   adn
2. run minicom on the Licor port (ttyS2=2m, ttyS7=7m, ttyS11=16m, ttyS14=30m, ttyS17=43m)
   minicom ttyS2
3. If the baud rate agrees with minicom (9600) you should see the default Licor output
4. Send a break character, by doing "control-A f" from minicom
   ctrl-Af
5. Send these strings to the Licor:

   (Outputs (RS232 (EOL "0A") (Labels FALSE) (DiagRec FALSE) (Ndx FALSE) (Aux FALSE) (Cooler FALSE)
   (CO2Raw TRUE) (CO2D TRUE) (H2ORaw TRUE) (H2OD TRUE) (Temp  TRUE) (Pres TRUE) (DiagVal TRUE)))
   (Outputs (BW 10) (Delay 0) (RS232 (Freq 10.0)  (Baud 9600)))
   (Outputs (Dac1 (Source NONE)(Zero 0)(Full 5)) (Dac2 (Source NONE)(Zero 0)(Full 5)))
   

6. You won't see much output, perhaps just 1 column of digits on the right-hand-side, since the Licor is sending just a line-feed termination and no carriage-return. You can turn on line wrap in minicom, with "control-A w" to see the data stream wrap from side to side:
   ctrl-Aw
7. Exit minicom with control-A q
   ctrl-Aq
8. restart the data process:
   aup
9. check the Licor data with rserial. It may take 30 seconds or so for the data system to open the port. During that time rserial will report an error about not finding the sensor. Eventually it should work.
   rs 2
10. The data should look like:

    248\t0.06460\t12.4193\t0.01218\t81.586\t16.10\t76.1\t\n
    248\t0.06462\t12.4179\t0.01207\t81.459\t16.11\t76.1\t\n
    

11. Exit rserial with control-D
    ctrl-d

Calibration process for LiCors 7500s.  I calibrated all five LiCors.  Calibration included post cal, desiccant change, spot check, zero/span.  I used N2 tank which went through a scrubber of Ascarite II and Drierite to give the zero for both CO2 and H20. 

Post-Cal conditions were checking zeros, span and dew point.  Spans included for CO2 were a bottle of 394.611ppm and 378.867ppm.  For H2O I used the Thunder Scientific, humidity chamber, set at 25C at 80%RH.  Dew point was equal to 21.31C.

Zero Post-Conditions:  Pressure 85.04kPa, Temp=27.3C

Span Post-Conditions:  Column2 is standard 394.611ppm; Column3 is standard 378.867ppm; Column4 is dew point standard 21.31C

Quick Check after desiccant was changed and ran for overnight.  Pressure 82.62kPa, Temp 24.33C

Zero Calibration:  CO2 and H20 were set to zero value.

Span Calibration:  CO2 was spanned to 394.611ppm; H20 was spanned to dew point 21.31C.

The TRH sensors went through a post cal check before re-calibration.

Here are the results.

Temperature: Tested over the range of -30 to 30. It has been almost 1 year since these sensors were calibrated

Relative Humidity: Tested over 10% to 90% at temperatures 25, 10, -3

The Licor 7500 and TRH sensors were removed on 3/29. They will be re-calibrated and re-installed in about 2 weeks.