CASES97: Logbook Entries

CASES97: RAD Messages: 9 Entries..

Return to Logbook Contents Page
Entry Date Title Site Author #Graphics
273 Wed 24-Nov-1999Calibration of 1/2 bubbleOncley, Steve
271 Wed 24-Nov-1999Rad maintainance summaryOncley, Steve
270 Fri 21-May-1999Recalibration of LicorsallDelany, Tony
263 Tue 24-Jun-1997PAR sensors at site s77Delany, Tony
220 Fri 16-May-1997Tsfc Has Bad Aim At St. 6Jirak, Cathy
95 Thu 24-Apr-1997Campbell loggers at 7 and 87Semmer, Steve
77 Tue 22-Apr-1997vegguie removed from #77Oncley, Steve
54 Sat 19-Apr-1997PAR sensors7Delany, Tony
46 Fri 18-Apr-1997Cal factors for 4-comp rad array7Delany, Tony


273: RAD, Site , Wed 24-Nov-1999 16:54:19 MST, Calibration of 1/2 bubble
Using a tilt platform, I crudely estimate that changing the Q7 level 
from having the bubble centered to having the center of the bubble on
the scribed circle (is this what is meant by "1/2 bubble"?) to be
equal to 37 minutes of arc.  For field purposes, we should be able
to assume that this is 1/2 degree.

P.S.  I calculate that a 1/2 degree tilt lowers the net radiation by about
0.5%:

The untilted net radiation measurement is:  2 pi R^2 sigma ( T1^4 - T2^4 ).
The area of the "wedge" exposed to the other surface from a tilted
sensor is:  4 pi R^2 (theta/360), for a tilt angle, theta, in degrees.
Thus, the tilted measurement is:  2 pi R^2 sigma ( T1^4 - T2^4) +
 4 pi R^2 (theta/360) sigma ( T2^4 - T1^4 - T1^4 + T2^4 ) =
2 pi R^2 sigma ( T1^4 - T2^4 ) * [1 - 4 (theta/360) ].

For theta 37/60 degrees, [] = 1 - 0.7%.  
Thus, for Rnet = 600 W/m2, the error due to observed tilts is about 4 W/m2.



271: RAD, Site , Wed 24-Nov-1999 16:41:09 MST, Rad maintainance summary
Summary from logbook entries:

Site 1:
4/9  2012       setup
5/8  1946       cleaned net & licor

Site 2:
4/9  1616       setup
5/8  1722       leveled net (off by 1/2 bubble)
~5/23 teardown	the cows chewed on the [net] domes, but that probably 
		happened recently

Site 3:
4/16 1944       setup, but not correctly
4/27 2146       moved to real location
5/13 1917       cleaned & leveled net (off by 1/2 bubble)
~5/23 teardown  the [net] dome was slightly dimpled

Site 4:
4/12 1813       setup
4/19 2325       mounted licor
5/5  1035       leveled net (slanted to west)

Site 5:
4/28 1821       installed
5/3  1740       cleaned licor (dusty)
5/4  2017       cleaned net (dirty)
~5/23 teardown	the [net] dome was dirty and smashed down

Site 6:
4/7  1333       setup?
5/12 1711       cleaned net

Site 7:
4/18 1834       setup?

Site 8:





270: RAD, Site all, Fri 21-May-1999 16:47:07 MDT, Recalibration of Licors
This file was originally generated by Steve Oncley on 25 Feb''99 
using calibration summary (from factory certificates in Cathy's files)

The file was modified by Tony delany 21 May 1999 to include the later 
calibrations done by Don Nelson
To see how Don presented the sensitivity see below.

Sensor  1994 calib 1997 calib 1999 calib     CASES97 site
7121    53.3       -          52.7           8
7122    50.8       50.4       48.8           4
7922    -          50.6       49.0           3
9024    61.7       -          -
10835   66.0       65.6       62.6           6
10836   72.7       73.0       -              5 (also Tblmtn, Devel)
13331   86.9       89.7       87.3           7
26596   -          88.5       92.8           1
26597   -          86.5       89.8           2

All values in microamps/(1000 W/m2).  Multiply by a resistance of 147 ohms
to get microvolts/(1000 W/m2).  We usually use an amp/filter gain of 200
with this sensor.

1999 calibration data reported by Don Nelson was sensitivity in milleVolts/Wm-2
I have converted it to the same form as the previous calibration data by 
dividing by 147 ohms x 1000
Sensor  milleVolts/Wm-2  divided by 147 ohms x 1000 = microamps/Wm-2 
7121    7.75                                          52.7          
7122    7.18                                          48.8           
7922    7.21                                          49.0          
9024     -                                            -
10835   9.20                                          62.6         
10836    -                                            -     
13331   12.84                                         87.3      
26596   13.64                                         92.8    
26597   13.20                                         89.8  


Ratio of (1997 or 1994 calib) / (1999 calib)
Sensor  1994 calib 1997 calib 1999 calib Ratio     CASES97 site
7121    53.3       -          52.7       1.011     8
7122    50.8       50.4       48.8       1.033     4
7922    -          50.6       49.0       1.033     3
10835   66.0       65.6       62.6       1.048     6
13331   86.9       89.7       87.3       1.027     7
26596   -          88.5       92.8       0.954     1
26597   -          86.5       89.8       0.963     2

263: RAD, Site 7, Tue 24-Jun-1997 17:41:16 GMT, PAR sensors at site s7
The Photosynthetically Active Radiation, PAR, or Quantum sensors
used during CASES97 were deployed only at the Super-Site, s7.

Three PAR sensors borrowed from NOAA were mounted on the dark
horse at s7. One was used to monitor incoming PAR,one was used to measure
outgoing PAR, and one was kept as a spare 

All sites, including s7in had Licor solar incoming radiation
sensors, soldn, and it is intended to define a ratio

                        PAR/soldn

for s7 and then to use soldn at all other sites to obtain
the respective PAR's.

The two NOAA sensors used both were connected via 604 ohm adapters:

rad.par.in 
 NOAA S/N Q22668, cal date 3 Sept''96
 -168.4 umol/m^2/s/uA with 604 ohm adaptor
        -168.4/604 = .2788 umol/m^2/s/uV
        cal factor:  .2788e6 umol/m^2/s/V
        
rad.par.out
  NOAA S/N Q22666, cal date 3 Sept''96 
 -181.8 umol/m^2/s/uA with 604 ohm adaptor
        -181.8/604 = .3010 umol/m^2/s/uV
        cal factor: .3010e6 umol/m^2/s/V
        
spare
  NOAA S/N Q22678, cal date 3 Sept''96
 -169.8 umole/m^2/s/uA with 604 ohm adaptor

PS added by Gordon Maclean, June 24:
A gain of 1000 was applied to these analog channels, which caused them
to saturate the +-5V AtoD during the day. (A gain of 100 would have been
a better choice).



220: RAD, Site , Fri 16-May-1997 19:54:36 GMT, Tsfc Has Bad Aim At St. 6
Tsfc at station #6 seems to be pointed at both a small patch of wheat growing 
on the very edge of a corn field and at the corn in the field. Probably when 
the station was set up there was bare ground every where. The wheat is about 
3 feet tall. Since this was noticed, it was decided not to repoint it.

95: RAD, Site 7, Thu 24-Apr-1997 16:28:19 GMT, Campbell loggers at 7 and 8
  The loggers at 7 and 8 where changed to an output rate
of 1 sec. Recycling power will set the loggers back to a
5 sec output rate. The change was made to clean up the
cockpit displays.


77: RAD, Site 7, Tue 22-Apr-1997 16:04:52 GMT, vegguie removed from #7
Since Bob Grossman thinks the veggiemeter should be at the grassland site
(#8), I have just removed it from #7.  I'll reconfigure "ops1" now.

54: RAD, Site 7, Sat 19-Apr-1997 19:33:06 GMT, PAR sensors
Photosynthetically-Active Radiation

There are two PAR sensors at site 7, mounted on the cross beam of the
radiation stand. They are on the upper and lower surfaces of a set of  plates.

  Sensor     Serial#   Cal date         Multiplier    Units

  par.in     Q22668    03 Sept''96      -168.4        umol. s-1. m-2 / uA

  par.out    Q22666    03 Sept''96      -181.8        umol. s-1. m-2 / uA


  The wheat rows do not run North-South but rather about 20 degrees to the west
  of South



46: RAD, Site 7, Fri 18-Apr-1997 18:34:35 GMT, Cal factors for 4-comp rad array
The cal factors for the piranometers and pyrgeometers deployed at super site
as components of the four component radiometer array.

NB The ASTER pyg.out was broken. It is replaced by another pyrgeometer with
only a single dome thermister. As the pyg.out dome is not subjected to
direct solar heating the single dome thermister is adequate.

	   Radiometer       Serial #       Date of cal    Calfactor uV/Wm-2

           ASTER psp.in     26214          8/92           8.57 

           ASTER psp.out    26226          8/92           8.63 

           ASTER pyg.in     29260          9/92           3.56 (3.27 after mod?) 
           L6    pyg.out    29137          4/92           4.05