14. TECP objectives
n Learn more about how heat
flows in Martian regolith
n Ground-truth for plentiful remote
sensing data
n Determine if unfrozen water
may exist under sunlit
conditions in trench
n Answers: “Can liquid water
occur on Mars?”
n Study vapor phase water
transport
n Examine how ice migrates from
pole to pole
Prototype TECP probe
15. WP4C Dewpoint Water Potential Meter
n Measures Water Potential of Soils, Seeds,
Organic Matter, etc.directly MPa and Pf (log
base 10 of MPa)
n Easy to use, more robust than thermocouple
psychrometers
n Temp. controlled
n Range: -0.05 to -300MPa
16. Chilled-mirror
Dewpoint Technique
Infrared Sensor
Optical Sensor
Mirror is chilled until dew is
formed. The temperature at which
saturation is achieved is
determined by observing
condensation on a chilled surface
(mirror).
Advantages
• Wide measurement range
• Rapid measurement ~ 5 min.
• High reliability
• Low Maintenance
Sample
Mirror
Fan
18. pF Plot to get Soil Swelling
y = -17.02x + 7.0381
R2
= 0.9889
y = -29.803x + 7.0452
R2
= 0.9874
y = -97.468x + 6.8504
R2
= 0.9688
3
3.5
4
4.5
5
5.5
6
6.5
7
7.5
0 0.05 0.1 0.15 0.2
Water Content (g/g)
Suction(pF)
L-soil
Palouse
Palouse B
19. Expansive Soil Classification from
McKeen(1992)
Class Slope Expansion
I > -6 special case
II -6 to -10 high
III -10 to -13 medium
IV -13 to -20 low
V < -20 non-expansive
20. Vapor Sorption Analyzer (VSA)
20
Range: -10 to -475 MPa.
Accuracy: ±1MPa or ±1%
Operating Temperature: 15 to 40°C
• Auto-generated moisture release
curves
• Static humidity feature to watch
how soil adsorbs water over time
21. VSA data
0
5
10
15
20
25
-500 -400 -300 -200 -100 0
Water Potential (Mpa)
WaterContent(g/100g)
Bentonite
Palouse B
NM clay
Walla Walla
Royal
L-soil
0
5
10
15
20
25
0 0.2 0.4 0.6 0.8 1
Water Activity
WaterContent(g/100g)
Bentonite
Palouse B
NM clay
Walla Walla
Royal
L-soil
23. AccuPAR Ceptometer
model LP-80
What does the AccuPAR Measure?
n PAR (Photosynthetically Active
Radiation
n LAI (Leaf Area Index) calculated
using PAR measurements above
and below the canopy, and using
other variables.
Decagon invented this type of
instrument in 1988 (Sunread, Sunscan,
PAR-80, LP-80)
24. What is PAR? n Acronym for
Photosynthetically
Active Radiation.
n Defined as the light in
the 400 to 700 nm
range of the
spectrum (visible
range).
n Light that is most
useful to plants for
photosynthesis.
n Expressed by
AccuPAR as
µmol m-2 s-1, a
measure of photon
flux density
Electromagnetic Spectrum
25. Leaf Area Index (LAI)
What is LAI?
n Defined as: total leaf area
per unit ground area
n Indication of Canopy density,
biomass
n Used to monitor growth,
infestation
n Often used for ground-
truthing Remote Sensing LAI
data
26. Calculating LAI
n Above-canopy PAR
n Below-canopy PAR
n x (leaf distribution parameter)
n Zenith angle (automatically calculated)
n Fb (fraction of beam radiation)
AccuPAR calculates LAI based on equations
from Goudraan, Norman, and Campbell using
measured and supplied data:
27. Comparison Studies
“Comparisons of three Leaf Area Index Meters in a
Corn Canopy” by W.W. Wilhelm, K. Ruwe, M.R.
Schlemmer in Crop Science 40:1179-1183 (2000)
n Shows that all three types are similar, AccuPAR/
SunScan somewhat better than LAI-2000.
28. Spectral Reflectance Sensors (SRS)
• NDVI
bands:
630
nm
and
800
nm
center
wavelengths
• PRI
bands:
532
nm
and
570
nm
center
wavelengths
• NIST
traceable
calibra5on
stored
onboard
• Cosine
diffusers
for
hemispherical
measurement
• 20°
sealed
field
stops
for
direc5onal
measurements
• Dimensions:
43
x
40
x
27
mm
• Epoxy-‐sealed
sensor
body
–
robust
design
• SDI-‐12
digital
sensor
• Decagon
Em50
and
CSI
datalogger
compa5ble
PRI
PRI
NDVI
NDVI Hemispherical view sensors
Directional field stop sensor
Stacked SRS sensors
NDVI + PRI
29. How to Measure NDVI and PRI
PRI
NDVI
NDVI
NDVI
PRI
Only two bands are needed to calculated NDVI or PRI.
30. Typical canopy reflectance spectrum
redNIR
redNIR
NDVI
ρρ
ρρ
+
−
=
Calculating NDVI
NIR
red
• NDVI is calculated from
measurements of percent
reflectance (ρ) in the red and
near-infrared (NIR) regions of
the electromagnetic spectrum.
• Percent reflectance is the ratio
between upwelling (from the
canopy) to downwelling (from
the sky) radiation. Requires a
measurement of both.
• Red band is related to
chlorophyll content (high
absorption), NIR band is
related to leaf cell structure
(high scattering).
NDVI values range from -1 to 1.
31. Gamon & Surfus (1999) New Phyt.
570531
570531
ρρ
ρρ
+
−
=PRI
Calculating PRI
• PRI (Photochemical
Reflectance Index) was
designed to estimate Light
Use Efficiency (LUE) by
detecting changes in the
xanthophyll cycle
• Xanthophyll pigments
change rapidly in
response to environmental
conditions
PRI values range from -1 to 1.
32. Measurement Considerations
Image credit: Chris Gough
• Reflectance measurements require a
top-down view of the canopy to
measure upwelling radiance.
• Up-looking sensors require
unobstructed view of the sky.
• Dual-view instruments (up/down) are
a convenient way of measuring both
incident and reflected light for
calculating percent reflectance. They
also account for changing sky
conditions (e.g., clear vs. cloudy sky
conditions).
• SRS are lightweight, low power, and
have a small footprint, making them
easy to mount almost anywhere.
Downwelling
radiation
Upwelling
radiation
33. Leaf
Porometer
Model SC-1
For measurement of
stomatal conductance
• Steady-state technique
• Stomatal conductance is a
primary indicator of plant stress
under drought conditions
34. How does it work?
n A chamber with a fixed
diffusion path is clamped to
the leaf surface
n Steady-state technique;
measures vapor pressure at
two locations in a fixed
diffusion path
n Calculates flux and gradient
from the vapor pressure
measurements and the known
conductance of the diffusion
path.
Atmosphere
Desiccant
35. What can I do with a porometer?
n Water use and water balance
n Use conductance with Fick’s law to determine crop
transpiration rate
n Develop crop cultivars for dry climates/salt affected
soils
n Determine plant water stress in annual and
perennial species
n Study effects of environmental conditions
n Schedule irrigation
n Optimize herbicide uptake
n Study uptake of ozone and other pollutants
36. Case study: Washington State
University wheat
• Researchers using steady state porometer
to create drought resistant wheat cultivars
– Evaluating physiological response to drought
stress (stomatal closing)
– Selecting individuals with optimal response
38. Mini-Disk Infiltrometer
For measurement of Soil
Hydraulic Conductivity
n Soil Hydrology Studies
n Erosion Studies
n Classroom Instruction
FEATURES:
® Adjustable suction rate (0.5 to
6cm)
® Sintered stainless steel disk
® Removable parts
39. Dielectric Soil
Moisture Sensors
n Hi-frequency capacitance (FDR)
-- Measures the dielectric constant
of the soil
n Designed to be buried in soil for
long-term monitoring of soil moisture
n Measurement is made by processor
inside probe head
40. Analog soil moisture sensors
10HS: 10 cm probe length,
3-15 VDC
— large sample area (~1 liter)
EC-5: 5cm probe length,
2.5-3 VDC
— smallest length
MAS-1: 4-20 mA sensor,
5cm probe length
— smallest length
41. Digital Sensors
GS3: Water content, EC
(0-23 dS/m) and
temperature. For soil or soil-
less substrates
5TE: Water content, EC
(0-23 dS/m) and
temperature. For field soils
only.
5TM: Water content and
temperature. For field soils
All digital sensors are SDI-12 compatible
47. Em50 Data Logger
n Weatherproof,-40° to 45°C
measurement
n 5 ports
n Uses 5 AA alkaline batteries,
low power usage.
n Programmed via RS232 cable
connected to COM Port.
n Measures every minute, then
averages and stores readings
according to how it’s
programmed. It can store any
interval between 1min. and 1
day.
n Measures other micro-
environment sensors that
Decagon sells
Storage Capacity:
1MB non-volatile flash
(28,672 scans on all 5
ports).
48. VP3 RH/Temp Sensor
and Radiation shield
n Digital sensor for use with Em50
loggers
n Measures and logs vapor pressure
and temperature with a capacitance
sensor and thermistor
n Should be used with a radiation
shield for outdoor use
49. Temperature Sensor
n Measures from – 40°C to
60°C
n Accuracy: ±0. 5 ° from 5 to
40°C; ±1°C outside this
range
n Can be used in air, soil, or
liquid. If used in air, a
radiation shield should be
used.
50. Leaf Wetness Sensor
n Determines presence and
duration of leaf moisture
n Similar technology to EC-5,
does not require painting or
maintenance
n All probes are calibrated to
same dryness baseline
voltage
n Water condenses and
evaporates from the surface
at the same rate as it does
on leaves
52. MPS-2 Matric
Potential Sensor
n For in-situ monitoring
of water potential
n Range: -10 to -500
kPa(pF 2 to pF 3.71)
n Uses capacitance
method to measure
water content of a
known ceramic matrix
53. Sensor Theory
n Measure water content of a known porous material with
a pre-established SWCC, giving us matric water
potential.
Matrix (Side View) Sensor (Side View)
Confined
EM Field
Metal Plate
Metal Plate
54. MPS-2 Advantages
n No maintenance
n Good accuracy in plant-available
range
n Each sensor pre-calibrated
n Also measures Soil temperature
Water Potential is a better
indicator of plant available water
than water content
55. Pyranometer / PAR sensor
n Manufactured by Apogee
Instruments
n Configured to connect to
our Em50
n Measures total solar
radiation (W/m2), PAR
sensor measures µmol/
m2/s
n Important for energy
balance studies and
micro-climate monitoring.
n Comes with leveling plate
59. Em50R Radio-enabled Logger
n Any number of Em50Rs can
transmit to one Data Station
or Rm1.
n Range is from 1 to 3 km,
depending on interference.
Range can be increased
with use of antenna.
n Transmits data when
measurement is taken
Same specifications as normal Em50, only Em50R has a
radio transmitter that sends collected data via telemetry
60. DataStation
• Collects data from any
number of Em50Rs
• Can operate on solar power
or AC power
• Download direct to PC or
PDA at your convenience
• Has Radio Telemetry test
capability to help with
placing Em50R loggers.
62. Em50G: What is it?
GSM-enabled logger,
delivers data via GSM
providers to Decagon’s
server
Data is available at any
internet connection
63. Why the Em50G?
• 2.4 Ghz Radio can be problematic (range,
wifi interference)
• Single point remote locations
• Ease of data acquisition via internet
64. Computer + Software
+ Internet Em50G
Logger + Sensors
GSM/GPRS
Cell Tower
Internet
Decagon
Internet Server
64
How does it work?
65. ECHO Utility
You can:
n Configure ports
n Name logger
n Set logging interval
n Download data
n Scan ports
- Does not graph
- Cannot apply
calibrations in
program
Free software that
comes with any
Em50 and Em5b
purchase
66. CTD (conductivity, temp., depth sensor)
Decagon Devices, Inc.
Confidential and Proprietary
Do Not Copy or Redistribute66
Water Depth
Range 0 to 3.5 m
Accuracy ±0.2 % of span
Resolution 1 mm
Electrical Conductivity
Range 0 to 120 dS/m (mS/cm)
Accuracy ±5% of reading
Resolution 1.2% of reading
Temperature
Range -40 to + 50 °C
Accuracy ±1 °C
Resolution 0.1 °C
68. ES-2 EC and T sensor
n For monitoring EC and
temperature in liquid water
Range:
Electrical Conductivity: 0 to 120 dS/m
Temperature: -40 to 50°C
Resolution:
Electrical Conductivity: 0.001 dS/m
Temperature: 0.1°C
Accuracy:
Electrical Conductivity: + 0.01 dS/m or + 10 %
(whichever is greater)
Temperature: + 1°C
69. Drain Gauge:
Passive Capillary Lysimeter
n Purpose: to
measure deep
drainage (flux
and solute
analysis) below
the root zone
Model G3 Model G2
70. Drain Gauge G-2: How it works
1. Drain Gauge is installed below the
root zone
2. Water travels through divergence
control tube, then through wick to
measurement chamber.
3. Water level is continuously
monitored by depth sensor inside
chamber. When 31ml of water fills
the chamber, it empties via a
siphon into a collection chamber.
Each siphon event corresponds to
1mm of infiltration.
4. Water samples can be extracted
from collection chamber using a
syringe.
5. Excess water exits through the
overflow port, leaving a constant
volume in the sampling reservoir.
72. Drainage Data
Drain Gauge data
(potato field, S. Idaho)
0
100
200
300
400
500
600
700
800
900
55 60 65 70 75 80 85
time
(days)
draingaugeoutput
(mV)
73. Drain Gauge G3
n Sampling Reservoir Volume: 3 L
n Accuracy: ± 2% of full scale
n Total Length: 1.5m
n Divergence Control Tube (DCT) Length :60 cm
n Construction Material: Stainless Steel or PVC
DCT
Decagon Devices, Inc.
Confidential and Proprietary
Do Not Copy or Redistribute73
• Measure deep drainage flux
(past the root zone)
• Analyze water samples
• Also measures EC and Temp.
• Sealed lower portion
75. Thermal Conductivity,
Thermal Diffusivity,
Thermal Resistivity and
Specific Heat Capacity.
n Extended
temperature range:
-50 to 150°C.
n Data storage.
n Smart sensors
n Can be used with
liquid samples.
PRO
