| Entry
| Date
| Title
| Site
| Author
| #Graphics
|
| 5 | Wed 03-Jun-1992 | Radiation and soil sensor cabling confi | none | Operator
|
| 7 | Wed 03-Jun-1992 | GRAVIMETRIC SOIL MOISTURE | none | Operator
|
| 11 | Thu 04-Jun-1992 | T.soil.snd is broken: | none | srs
|
| 18 | Fri 05-Jun-1992 | Burying the Sand T multi-plexer in the | none | acd
|
| 38 | Sun 07-Jun-1992 | Cloud of dust. | none | acd
|
| 45 | Sun 07-Jun-1992 | RADIATION TESTING: | none | srs
|
| 47 | Sun 07-Jun-1992 | FIX TO RADIATION: | none | srs
|
| 51 | Mon 08-Jun-1992 | CALIBRATION FACTORS FOR RADIATION AND S | none | acd
|
| 81 | Wed 10-Jun-1992 | Radiation sensor levels checked. | none | acd
|
| 83 | Wed 10-Jun-1992 | Darkhorse orientaion shot. | none | acd
|
| 87 | Thu 11-Jun-1992 | Pyg.out problem | none | acd
|
| 89 | Thu 11-Jun-1992 | PYG.OUT.CASE is ?: | none | srs
|
| 96 | Fri 12-Jun-1992 | GRAVIMETRIC SOIL MOISTURE | none | Operator
|
| 101 | Sat 13-Jun-1992 | GRAVIMETRIC SOIL MOISTURE | none | acd
|
| 121 | Wed 17-Jun-1992 | Checked radiation sensor gains from | none | twh
|
| 124 | Thu 18-Jun-1992 | Disconnected Pyg.out temperature leads | none | twh
|
| 134 | Mon 22-Jun-1992 | Tsoil.sand multiplexing appears to have | none | twh
|
| 146 | Wed 24-Jun-1992 | Removed the pyg.out pyrgeometer and che | none | twh
|
| 147 | Wed 24-Jun-1992 | Tsoil.grass died around 2200 GMT on JD | none | twh
|
| 163 | Fri 14-Aug-1992 | Post calibration of Tsoil probes | none | srs
|
| 165 | Wed 03-Mar-1993 | Soil thermal conductivity correction | none | acd
|
- 5: RAD , Site none, Wed 03-Jun-1992 17:12:12 GMT, Radiation and soil sensor cabling confi
Radiation and soil sensor cabling configuration.
The tall darkhorse was setup at the 250m station with the radiation
sensors. The soil heat and temperature sensors were installed nearbye.
Four analog mux cables, A, B, C, and D from the darkhorse break-out-box
and two analog mux cables, E and F, from another analog break-out-box
ran to cosmos.
The cabling from the break-out-boxes was as follows.
Left hand side of darkhorse break-out-box:
A psp.out psp.in pyg.out pyg.in
3 2 1 0
cosmos:111 cosmos:110 cosmos:109 cosmos:108
B pyg.in.dome pyg.in.case pyg.out.dome pyg.in.case
4 5 6 7
cosmos:112 cosmos:113 cosmos:114 cosmos:115
Right hand side of darkhorse break-out-box:
C net.rad T.surf G1.bsh.8cm G2.grs.8cm
0 1 2 3
cosmos:116 cosmos:117 cosmos:118 cosmos:119
D G3.snd.8cm - - -
4 5 6 7
cosmos:120
Stake mounted analog break-out-box:
E Tsoil.bsh index.Tsoil.bsh Tsoil.grs index.Tsoil.snd
0 1 2 3
cosmos:124 cosmos:125 cosmos:126 cosmos:127
F Tsoil.snd index.Tsoil.snd - -
4 5 6 7
cosmos:128 cosmos:129
The coupling into cosmos was as follows.
cosmos analog 0 = t.250.10m1 + q_kh2o_2a + conc.sf6.250.10m + mode.sf6.250.10m
cosmos analog 1 = bugflux data (query there are 5 bugflux channels)
cosmos analog 2 = A
cosmos analog 3 = B
cosmos analog 4 = C
cosmos analog 5 = D
cosmos analog 6 = E
cosmos analog 7 = F
- 7: RAD , Site none, Wed 03-Jun-1992 19:04:39 GMT, GRAVIMETRIC SOIL MOISTURE
GRAVIMETRIC SOIL MOISTURE
Number: 7 Written 06-JUN-92 by ACD
Type: RAD Project: FOOTPRINT92
Title: GRAVIMETRIC SOIL MOISTURE
---------------------------------------
Samples taken in the vicinity of the darkhorst.
Samples taken in triplicate
Samples weighed within an hour of collection to give WET WEIGHT
Samples then dried in the oven at 110 deg C for 24 hours to give DRY WEIGHT
Soil samples were weighed with taring of an empty Al dish.
DATE TAKEN WET WEIGHT DRY WEIGHT DIFFERENCE GRAVMOISTURE
(JULIAN) (GRAMS) (GRAMS) (GRAMS) (PERCENT)
_______________________________________________________________________________
5 Jun 92
Friday
157
A 25.59 25.48 0.11 0.43
SAND B 33.17 33.02 0.15 0.45 = 0.43%
C 35.11 34.97 0.14 0.40
A 23.76 23.69 0.07 0.30
GRASS B 23.75 23.67 0.08 0.34 = 0.30%
C 19.58 19.53 0.05 0.26
A 22.59 22.46 0.13 0.58
BUSH B 21.72 21.60 0.12 0.56 = 0.57%
C 29.33 29.16 0.17 0.58
11 JUN92
THURSDAY
A
SAND B
C
A
GRASS B
C
A
BUSH B
C
- 11: RAD , Site none, Thu 04-Jun-1992 02:18:37 GMT, T.soil.snd is broken:
T.soil.snd is broken:
the T.soil.sand goes on and off
throughout the day. It may be a temperature
problem.
- 18: RAD , Site none, Fri 05-Jun-1992 00:11:40 GMT, Burying the Sand T multi-plexer in the
Burying the Sand T multi-plexer in the sand
The index of Tsoil.snd suffered from malfunction leading
to overlong timing intervals.
To alleviate the temperature effect at 12:30 today the multiplexer was buried at 20 cm depth
- 38: RAD , Site none, Sun 07-Jun-1992 01:24:36 GMT, Cloud of dust.
Cloud of dust.
At approximately 17:00 pdt a large dust clouid
swept across the site from the direction of the
200E area
- 45: RAD , Site none, Sun 07-Jun-1992 20:37:39 GMT, RADIATION TESTING:
RADIATION TESTING:
Tests took place between 20:00 and
20:30z on the radiation channels. Therefore
these data are questionable.
- 47: RAD , Site none, Sun 07-Jun-1992 21:05:51 GMT, FIX TO RADIATION:
FIX TO RADIATION:
The gain settings on the
psp.in, psp.out, pyg.in, pyg.out
were set to 100 not 200. This has
been corrected as of 5 minutes ago.
This should be noted for post analysis
work.
- 51: RAD , Site none, Mon 08-Jun-1992 00:15:57 GMT, CALIBRATION FACTORS FOR RADIATION AND S
CALIBRATION FACTORS FOR RADIATION AND SOIL SENSORS
---------------------------------------
NOTE this was copied from the SJVAQS logbook and needs to be edited.
When it is satisfactorily edited this comment will be erase.
Calibration factors for radiation and soil sensors
(The tables shows the calibration factors available from the calibration
data, and allows an intercomparison with the prep.config factors used)
A copy of /home/aster/projects/FOOTPRINT92/ops1/prep.config will be compared
with these calibration factors. There will then be an affirmation check.
CHECKED DOWN TO HERE
CHANNEL SENSOR S/N CAL calibration factors
cosmos:100 pyg.in.rad 27907F3 3.44 uv/W m-2 linear cal #######, ###
gain = ?
Date of this calibration = ## ## ##
(prep.config: Checked ? )
cosmos:101 pyg.out.rad 26416F3 3.59 uv/W m-2 linear cal ######, ###
gain = ?
Date of this calibration = ## ## ##
(prep.config: Checked ? )
cosmos:102 psp.in.rad 26214F3 8.70 uv/W m-2 linear cal #####, ###
gain = ?
Date of this calibration = ## ## ##
(prep.config: Checked 14 Nov 91 )
103 psp.out.rad 26226F3 8.85 uv/W m-2 linear cal 8.6210E-2, 0.0
gain=200
Date of this calibration = ## ## ##
(prep.config: Checked 14 Nov 91 )
108 r.net 90076 13.4 W m-2/mV linear cal 2.0447E-2, 0.0
gain=100
Date of this calibration = ## ## ##
(prep.config: 2.0294E-2 , 0.0 )
109 t.surface 1041 100degree C/V linear cal 1.5259E-3, 25
offset=-25degree
gain=10
Date of this calibration = ## ## ##
(prep.config: Checked 14 Nov 91 )
113 par.rad Q9125 -143.47 linear cal 3.6246E-1, 0.0
umole/m-2 s/uA
gain=100
resistance=604ohm
Date of this calibration = ## ## ##
(prep.config: Checked 14 Nov 91 )
CHANNEL SENSOR CAL prep.config factor used
104 pyg.in.dome A0 = 3.5754E-3 c=thermistor 3.5754E-3
A1 = 2.6846E-4 2.6847E-4
A2 = 6.1043E-6 6.1043E-6
A3 =-3.6998E-6 3.6998E-6
offset = 4.8
Date of this calibration = ## ## ##
105 pyg.in.case A0 = 3.5764E-3 c=thermistor All OK 14nov91
A1 = 2.6860E-4
A2 = 6.3499E-6
A3 =-3.6393E-6
offset = 4.8
Date of this calibration = ## ## ##
106 pyg.out.dome A0 = 3.5829E-3 c=thermistor All OK 14nov91
A1 = 2.8073E-4
A2 = 1.7521E-5
A3 =-9.3759E-7
offset = 4.8
Date of this calibration = ## ## ##
107 pyg.out.case A0 = 3.5850E-3 c=thermistor All OK 14nov91
A1 = 2.8512E-4
A2 = 2.1575E-5
A3 = 1.2726E-7
offset = 4.8
Date of this calibration = ## ## ##
CHANNEL SENSOR CAL cal factors
117 Tsoil.a.index linear cal 1.5259E-4 ,0.0
offset =
gain=
Date of this calibration = ## ## ##
(prep.config: Checked )
118 Tsoil.b.index linear cal 1.5259E-4 ,0.0
offset =
gain=
Date of this calibration = ## ## ##
(prep.config: Checked )
119 Tsoil.c.index linear cal 1.5259E-4 ,0.0
offset =
gain=
Date of this calibration = ## ## ##
(prep.config: Checked )
CHANNEL SENSOR CAL prep.config factor used
116 Tsoil.a (mean) c=thermistor All OK 19 Nov91
A0 = 3.5869E-3
A1 = 2.6991E-4
A2 = 9.3435E-6
A3 =-3.5796E-6
offset = 4.7
Tsoil.a.1cm (0band)
A0 = 3.5920E-3
A1 = 2.6757E-4
A2 = 1.0719E-5
A3 =-3.6759E-6
offset = 4.7
Tsoil.a.3cm (1band)
A0 = 3.5932E-3
A1 = 2.6837E-4
A2 = 1.0903E-5
A3 =-3.6485E-6
offset = 4.7
Tsoil.a.5cm (2band)
A0 = 3.5931E-3
A1 = 2.6774E-4
A2 = 1.0867E-5
A3 =-3.6422E-6
offset = 4.7
Tsoil.a.7cm (3band)
A0 = 3.5925E-3
A1 = 2.6795E-4
A2 = 1.1015E-5
A3 =-3.6040E-6
offset = 4.7
Date of this calibration = 30 May 91
118 Tsoil.b (mean) c=thermistor All OK 19 Nov91
A0 = 3.5495E-3
A1 = 2.8734E-4
A2 = 4.3827E-6
A3 = 6.5799E-7
offset = 5.0
Tsoil.b.1cm (0band)
A0 = 3.5490E-3
A1 = 2.8731E-4
A2 = 4.2973E-6
A3 = 6.3137E-7
offset = 5.0
Tsoil.b.3cm (1band)
A0 = 3.5509E-3
A1 = 2.8736E-4
A2 = 4.3523E-6
A3 = 6.6114E-6
offset = 5.0
Tsoil.b.5cm (2band)
A0 = 3.5496E-3
A1 = 2.8727E-4
A2 = 4.2113E-6
A3 = 5.9975E-7
offset = 5.0
Tsoil.b.7cm (3band)
A0 = 3.5487E-3
A1 = 2.8718E-4
A2 = 4.4353E-6
A3 = 6.8631E-7
offset = 5.0
Date of this calibration = 30 May 91
120 Tsoil.c (mean) c=thermistor All OK 19Nov91
A0 = 3.5287E-3
A1 = 2.9799E-4
A2 = 3.7889E-7
A3 = 4.7208E-6
offset = 5.25
Tsoil.c.1cm (0band)
A0 = 3.5267E-3
A1 = 2.9787E-4
A2 = 3.0097E-7
A3 = 4.6895E-6
offset = 5.25
Tsoil.c.3cm (1band)
A0 = 3.5290E-3
A1 = 2.9797E-4
A2 = 3.0577E-7
A3 = 4.6887E-6
offset = 5.25
Tsoil.c.5cm (2band)
A0 = 3.5297E-3
A1 = 2.9813E-4
A2 = 3.2779E-7
A3 = 4.6919E-6
offset = 5.25
Tsoil.c.7cm (3band)
A0 = 3.5285E-3
A1 = 2.9794E-4
A2 = 4.7164E-7
A3 = 4.7596E-6
offset = 5.25
Date of this calibration = 30 May 91
CHANNEL SENSOR S/N CAL cal factors
CHANNEL SENSOR S/N CAL cal factors
CHANNEL SENSOR S/N CAL cal factors
110 G1.8cm blue#band 42.6 W m-2/mV linear cal 3.2502E-2, 0.0
gain=200
Date of this calibration = ## ## ##
(prep.config: Checked 14 Nov 91 )
111 G2.8cm red#band 38.4 W m-2/mV linear cal 2.9298E-2, 0.0
gain=200
Date of this calibration = ## ## ##
(prep.config: Checked 14 Nov 91 )
112 G3.8cm yellow#band 38.4 W m-2/mV linear cal 2.9298E-2, 0.0
gain=200
Date of this calibration = ## ## ##
(prep.config: Checked 14 Nov 91 )
Note added 3 Mar 93 by ACD:
The calibration values given here in the logbook for the soil
heat flux plates are those derived from the Apr87 calibration.
The Dec91 values are :
110 G1.8cm blue#band Serial number 87028 42.5 W m-2/mV
111 G2.8cm red#band Serial number 87034 38.0 W m-2/mV
112 G3.8cm yellow#band Serial number 87036 38.2 W m-2/mV
The correct values were used in the actual calculations during FOOTPRINT92.
See also the additional logbook entry commenting on the correctiondue to
the difference of thermal conductivity of the soil, the heat flux plate,
and the medium in which the heat flux plate was calibrated.
- 81: RAD , Site none, Wed 10-Jun-1992 17:44:43 GMT, Radiation sensor levels checked.
Radiation sensor levels checked.
There is an obvious difference between net.rad and sum.rad.
To assertain that it was not a leveling problem
I rechecked the level of Arnold ( oK to within 0.2 degrees both ways)
and the net radiometer ( bubble well inside circle.
- 83: RAD , Site none, Wed 10-Jun-1992 20:52:36 GMT, Darkhorse orientaion shot.
Darkhorse orientaion shot.
Using the theodolite and the ephemeris the alignment of the
darkhorse rail was 260 deg 48'.
The was difficulty in defining an appropriate edge to shoot.
In future a set of sighting wands attached to each end of the rail
needs to be employed.
- 87: RAD , Site none, Thu 11-Jun-1992 16:54:44 GMT, Pyg.out problem
Pyg.out problem
The pyg.out (and maybe also occasionally the pyg.in) show bad tcase
temperatures. This may be similar to the problem exibited during
STORMFEST.
- 89: RAD , Site none, Thu 11-Jun-1992 20:40:47 GMT, PYG.OUT.CASE is ?:
PYG.OUT.CASE is ?:
Tony has looked at the radiation
data and believes the pyg.out.case temperature
is in error. Upon examination of the signal
I would agree. The voltage output is too low.
The problem can't be fixed in the field.
With a post calibration of the termistors the
data can be corrected.
- 96: RAD , Site none, Fri 12-Jun-1992 22:21:41 GMT, GRAVIMETRIC SOIL MOISTURE
GRAVIMETRIC SOIL MOISTURE
Derived from Number: 7 Written 06-JUN-92 by ACD
Type: RAD Project: FOOTPRINT92
Title: GRAVIMETRIC SOIL MOISTURE
---------------------------------------
Samples taken in the vicinity of the base
Samples taken in triplicate
Samples weighed within an hour of collection to give WET WEIGHT
Samples then dried in the oven at 110 deg C for 24 hours to give DRY WEIGHT
Soil samples were weighed with taring of an empty Al dish.
DATE TAKEN WET WEIGHT DRY WEIGHT DIFFERENCE GRAVMOISTURE
(JULIAN) (GRAMS) (GRAMS) (GRAMS) (PERCENT)
_______________________________________________________________________________
5 Jun 92
Friday
157
A 25.59 25.48 0.11 0.43
SAND B 33.17 33.02 0.15 0.45 = 0.43%
C 35.11 34.97 0.14 0.40
A 23.76 23.69 0.07 0.30
GRASS B 23.75 23.67 0.08 0.34 = 0.30%
C 19.58 19.53 0.05 0.26
A 22.59 22.46 0.13 0.58
BUSH B 21.72 21.60 0.12 0.56 = 0.57%
C 29.33 29.16 0.17 0.58
11 JUN92
THURSDAY
A 34.38 34.14 0.24 0.70
SAND B 34.10 33.84 0.26 0.77 = 0.74
C 39.50 39.21 0.29 0.74
A 29.03 28.83 0.20 0.69
GRASS B 29.67 29.46 0.21 0.71 = 0.70
C 33.06 32.92 0.14 0.42 ignored
A 24.02 23.79 0.23 0.97
BUSH B 25.06 24.81 0.25 1.01 = 0.96
C 24.44 24.22 0.22 0.91
RAINFALL
12 JUN92
FRIDAY
A 27.40
SAND B 31.35
C 26.16
A 24.19
GRASS B 26.95
C 26.22
A 28.36
BUSH B 27.23
C 26.68
- 101: RAD , Site none, Sat 13-Jun-1992 18:54:27 GMT, GRAVIMETRIC SOIL MOISTURE
GRAVIMETRIC SOIL MOISTURE
Derived from Number: 7 Written 06-JUN-92 by ACD
Type: RAD Project: FOOTPRINT92
Title: GRAVIMETRIC SOIL MOISTURE
---------------------------------------
Samples taken in the vicinity of the base
Samples taken in triplicate
Samples weighed within an hour of collection to give WET WEIGHT
Samples then dried in the oven at 110 deg C for 24 hours to give DRY WEIGHT
Soil samples were weighed with taring of an empty Al dish.
DATE TAKEN WET WEIGHT DRY WEIGHT DIFFERENCE GRAVMOISTURE
(JULIAN) (GRAMS) (GRAMS) (GRAMS) (PERCENT)
_______________________________________________________________________________
5 Jun 92
Friday
157
A 25.59 25.48 0.11 0.43
SAND B 33.17 33.02 0.15 0.45 = 0.43%
C 35.11 34.97 0.14 0.40
A 23.76 23.69 0.07 0.30
GRASS B 23.75 23.67 0.08 0.34 = 0.30%
C 19.58 19.53 0.05 0.26
A 22.59 22.46 0.13 0.58
BUSH B 21.72 21.60 0.12 0.56 = 0.57%
C 29.33 29.16 0.17 0.58
11 JUN92
THURSDAY
A 34.38 34.14 0.24 0.70
SAND B 34.10 33.84 0.26 0.77 = 0.74
C 39.50 39.21 0.29 0.74
A 29.03 28.83 0.20 0.69
GRASS B 29.67 29.46 0.21 0.71 = 0.70
C 33.06 32.92 0.14 0.42 ignored
A 24.02 23.79 0.23 0.97
BUSH B 25.06 24.81 0.25 1.01 = 0.96
C 24.44 24.22 0.22 0.91
RAINFALL
12 JUN92
FRIDAY
A 27.40 24.75 2.65 10.7
SAND B 31.35 28.36 2.99 10.5 = 10.6
C 26.16 23.66 2.50 10.6
A 24.19 22.06 2.13 9.66
GRASS B 26.95 24.60 2.35 9.55 = 9.59
C 26.22 23.93 2.29 9.57
A 28.36 26.56
BUSH B 27.23 25.40
C 26.68 24.88
13 JUN92
SATURDAY
A 20.59 19.20
SAND B 23.57 21.96
C 19.60 18.27
A 22.10 20.29
GRASS B 21.20 19.44
C 20.02 18.38
A 24.14 22.99
BUSH B 29.53 28.10
C 24.46 23.29
14 JUN92
SUNDAY
A 25.17 23.36
SAND B 24.33 22.65
C 22.03 20.46
A 25.66 23.65
GRASS B 23.30 21.44
C 22.09 21.18
A 28.02 26.83
BUSH B 25.50 24.30
C 23.59 22.45
15 JUN92
Monday
A 24.73 23.39
SAND B 25.54 24.08
C 26.35 24.84
A 26.84 25.38
GRASS B 26.00 24.64
C 26.32 24.80
A 28.51 26.62
BUSH B 23.30 21.64
C 24.69 22.95
16 JUN92
Tuesday
A 31.04
SAND B 29.80
C 34.27
A 24.49
GRASS B 24.33
C 25.95
A 33.38
BUSH B 29.88
C 35.71
17 JUN92
Wednesday
A
SAND B
C
A
GRASS B
C
A
BUSH B
C
- 121: RAD , Site none, Wed 17-Jun-1992 19:08:23 GMT, Checked radiation sensor gains from
Checked radiation sensor gains from
10:45 am PDT to 11:45 am by putting
a ladder at the west end of the sawhorse,
measuring the sensor output at the
black box, and looking at the aster
output on ashow. The gains for the
psp's and pyg's were calculated to be
200 and that for the net radiometer was
100:
sensor output chnl counts gain
------------------------------------
psp.in 7.4 mV 110 9755 200
psp.out 1.0 mV 111 1388 200
pyg.in 1.2 mV 108 1542 200
pyg.out 2.7 mV 109 3620 200
net 42.2 mV 116 27500 100
By comparing to the calibration functions
and the factory calibration, these appear
to be the proper gains.
The maximum incoming solar radiation measured
at 622R today was 1.32 cal/cm^2/min = 921 W/m^2.
This is close to the ASTER psp.in max of
936.5 W/m^2.
- 124: RAD , Site none, Thu 18-Jun-1992 18:40:48 GMT, Disconnected Pyg.out temperature leads
Disconnected Pyg.out temperature leads
(12 V, Tdome, Tcase) at the black box
on the end of the sawhorse. From the
voltmeter, this did not appear to
change the pyg.out reading. The rad.soil
S plot also indicates no change in pyg.out.
I was on the ladder at the sawhorse from
11:10 to 11:20 am PDT.
- 134: RAD , Site none, Mon 22-Jun-1992 18:40:19 GMT, Tsoil.sand multiplexing appears to have
Tsoil.sand multiplexing appears to have
begun to fail on JD 171. It is now stuck
on the 7 cm level.
- 146: RAD , Site none, Wed 24-Jun-1992 21:19:41 GMT, Removed the pyg.out pyrgeometer and che
Removed the pyg.out pyrgeometer and checked its
battery. The battery was okay, so replaced it
(SN 26416F3, cal 3.59e-6 V/W m^-2) with
SN 26417F3, cal 4.79e-6 V/W m^-2.
Since the former pyg.out appeared to be wrong
all along, simply changed the calibration
coefficient from
(5 V)/(32767 counts)/(200 gain)/3.59e-6 V/W m^-2)
= 0.2125244 W m^-2 per count
to
(5 V)/(32767 counts)/(200 gain)/3.59e-6 V/W m^-2)
= 0.1592824 W m^-2 per count
- 147: RAD , Site none, Wed 24-Jun-1992 23:22:37 GMT, Tsoil.grass died around 2200 GMT on JD
Tsoil.grass died around 2200 GMT on JD 175.
Buried it today in an attempt to cool it
down.
- 163: RAD , Site none, Fri 14-Aug-1992 19:59:18 GMT, Post calibration of Tsoil probes
Post calibration of Tsoil probes
I had Allen do a calibration run on the Tsoil units
after he repaired the boards. Results of the tests can
be gotten from Steve Semmer.
The test consisted of placing the probes in an
aluminum block with the temperature reference device.
The electronics were also in the chamber at the time of the test.
A soak time of 1 hour was used at each temperature.
The first sensor looked pretty good.
There was a definite change in slope with respect to the temperature.
This may have been due to the electronics response to temperature
changes. Calibrations before StormFest and FootPrint did not allow
for the electronics to be subjected to changes.
All four probes followed each other.
The other two sensors did not fair as well.
There was a slope change; however, the tracking between sensors
was not that good. I will have Allen do another 3 point check
on this units.
The table below specs the worst error of each probe in the
range of 20C to 40C (FootPrint). The table also has the error
band if a simple linear fit were applied over the specified
temperature range. The error information is computed using the
pre-calibration coefficients with the post-calibration voltage
outputs.
The question to answer is do we want to apply a correction to
the FOOTPRINT and or STORMFEST data. The components changed on the
circuit boards should not have had a major impact on the sensor
output since the impedence of the mux swithes are low compared to
the thermistor values.
sensor mean error (C) linear fit error (C)
TS - REF TS - REF
TS1-1cm -.2 to .2 -.01 to .02
TS1-3cm -.2 to .2 -.01 to .01
TS1-5cm -.2 to .2 -.01 to .01
TS1-7cm -.2 to .2 -.01 to .01
TS2-1cm .1 to .3 -.04 to .07
TS2-3cm -.1 to .1 -.01 to .02
TS2-5cm .0 to .1 -.02 to .03
TS2-7cm -.1 to .0 -.02 to .04
TS3-1cm -.1 to .1 -.01 to .01
TS3-3cm -.1 to .1 -.01 to .01
TS3-5cm -.1 to .7 -.03 to .06
TS3-7cm -.1 to 1.0 -.06 to .11
- 165: RAD , Site none, Wed 03-Mar-1993 23:41:09 GMT, Soil thermal conductivity correction
Soil heat flux correction due to thermal conductivity, the Philip correction.
The surface heat flux, G, is obtained from the heat flux measured at 8cm and
the time varying mean temperature of the top 8cm of soil.
G(i) = G8(i)
+ Csoil*(0.08)*(Tsoil(i+1)-Tsoil(i-1))/(t(i+1)-t(i-1))
where: G8 is the heat flux at 8cm depth in the soil
Csoil is the soil heat capacvity
Tsoil is the mean temperature of the top 8cm of soil
and: the subscript i refers to data at ti seconds
(i-1) refers to data recorded at t(i-1)seconds
(i+1) refers to data recorded at t(i+1)seconds
Soil temperatures are measured at the depths of 1cm, 3cm, 5cm, and 7cm.
These are weighted to generate a mean soil temperature.
Tsoil = ((Tsoil1) + (3 * Tsoil3) + (3 * Tsoil5) + (Tsoil7))/8
Soil heat capacity is derived by determination of the mineral fraction,
the organic fraction and the water fraction of the soil.
For the FOOTPRINT92 deployment the soil heat capacity was:
Csoil = (1.26 + 6.01 wf) * 10**6
(J degK-1 m-3)
where: wf is the gravimetric soil moisture:
wf = (mass of fresh soil - mass of dry soil)/mass of dry soil
The gravimetric soil moisture, wf, is determined by collecting
surface to 8 cm depth soil samples, weighing them fresh, drying the samples
in an oven at 110 degrees C, and after 24 hours reweighing them.
An additional consideration in the determination of the soil heat flux
is that the soil heat flux measured at 8cm, G8,
needs to be corrected for the convergent flow of heat through the plate
due to the difference in the thermal conductivity of the soil and the plate.
The problem is compounded because the heat flux plates are calibrated in a
medium, the thermal conductivity of which is different still.
A relationship was composed by Philip (1961) and further extended by
Fritschen and Simpson (1989) which corrects for these factors.
G8(corrected) = G8(measured)
* (1 -1.92(t/d)(1 -(ks/kt))/(1 -1.92(t/d)(1- (km/kt)))
where t = transducer thickness
d = transducer diameter
kt = thermal conductivity of the transducer
km = thermal conductivity of the calibration medium, wet glass beads
ks = thermal conductivity of the soil
The values used for t, d, kt, and km were provided by
Radiation Energy Balance Systems
P.O.Box 15512, Seattle, WA 98115-0512
206-624-7221
with respect to the HFT1 square plates which they sold to us and have since
calibrated in Apr87 and Dec91.
Nominal dimensions of HFT1 heatflux plate 0.39cm thick, 3.2cm * 3.2cm.
This defines an effective diameter of 3.61cm, and a t/d of 0.39/3.61 = 0.108.
Values of kt = 1.00 W m-1 degC-1
km = 0.906 W m-1 degC-1
t/d = 0.108
km/kt = 0.906
The value for the thermal conductivity of soil, ks, is calculated from an
expression developed by McInnis (1981) which involves the gravimetric soil
water percentage, wf.
ks = 0.64 + (1.63 * wf) - 0.05 * e**(-17 * (wf)**2)
To confirm the reasonableness of these figures a sample calculation follows:
A typical value of wf = 0.08, would lead to a soil thermal conductivity of:
ks = 0.64 + (1.63 * 0.08) - 0.05 * e**(-17 * (0.08)**2)
ks = 0.64 + 0.13 - 0.05 * e**(-17 * 0.0064)
ks = 0.64 + 0.13 - 0.05 * e**(-0.1088)
ks = 0.64 + 0.13 - 0.05 * 0.897
ks = 0.64 + 0.13 - 0.045
ks = 0.725
This gives a ratio of ks/kt = 0.725
Substituting these values in the Philip correction term gives:
G8(corrected) = G8(measured)
* (1 -1.92(t/d)(1 -(ks/kt)))/(1 -1.92(t/d)(1- (km/kt)))
G8(corrected) = G8(measured)
* (1 -1.92(0.108)(1 -(0.725))/(1 -1.92(0.108)(1- (0.906))
G8(corrected) = G8(measured)
* (1 -1.92(0.108)(0.275))/(1 -1.92(0.108)(0.094))
G8(corrected) = G8(measured)
* (1 -0.057)/(1 -0.0195)
G8(corrected) = G8(measured)
* (0.943)/(0.981)
G8(corrected) = G8(measured)
* 0.961
This looks like a good number; a 4% correction for 8% soil moisture.