NRES 408/808 Instrumentation Demonstration -- Radiation Instrumentation
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Transcript of NRES 408/808 Instrumentation Demonstration -- Radiation Instrumentation
NRES 408/808Instrumentation Demonstration --
Radiation Instrumentation
Mark Mesarch
229D Hardin Hall
472-5904 or [email protected]
Office Hours
Homework Assignment 4 on Blackboard Questions:
Phone: 402.472.5904e-mail: [email protected]
229D Hardin Hall
Purpose of Demonstration
Introduction to Instrumentation• NRES 469/869 Bio-Atmospheric Instrumentation
Examples ---- Not Exhaustive
More Than Just Numbers
Net Radiation Budget
Rn = RSW - RSW + RLW- RLW
WhereRn = Net RadiationRSW = Short wave Incoming
RSW = Short wave Outgoing
RLW = Long wave Incoming
RLW = Long wave Outgoing
Net Radiation BudgetCalculated Net Radiaion and Individual Components
Grass Mulch on 9/14/2005
-200
-100
0
100
200
300
400
500
600
700
800
900
0 4 8 12 16 20 24
Time ( Decimal Hour )
Rad
iant
Ene
rgy
Flux
( W
m-2
)
Rsw In Rsw Out Rlw In Rlw Out Rn Calculated
Net Radiation BudgetMeasured
Net Radiation Budget
WhereRn = Net RadiationRSW = Short wave Incoming
RSW = Short wave Outgoing
RLW = Long wave Incoming
RLW= Long wave Outgoing
Rn = RSW - RSW + RLW- RLW
Net Radiation Budget
At 13:30 on September 14RSW = 803.38 W m-2
RSW = 141.16 W m-2
RLW = 318.94 W m-2
RLW= 523.05 W m-2
Rn = 803.38 – 141.16 + 318.94 – 523.05
= 458.11 W m-2
Rn = RSW - RSW + RLW- RLW
Net Radiation Balance
Rn (Calculated) = 458.11 W m-2
Rn (Measured) = 423.85 W m-2
What Caused the Difference?
Design Your Own Instrument Setup
What will the instrument “see”? How is the instrument installed? How to maintain the instrument?
How Instruments “See”
Field of View (FOV)
• Demo
How Instruments See
How Instruments See
Hemispherical View
How Instruments See
How Instruments See
Specific Field of View
How Instruments See
24o Field of ViewHemispherical
How Instruments SeeHemispherical 30o FOV
Reifsnyder,W. 1967. Agr Meteorol 4: 255-265
How Instruments See
Hemispherical vs specific Field of View (FOV)
Spatial coverage
Demo
How Instruments See
How Instruments SeeSpatial Measurement Alternative
How Instruments See Calculating absorbed fraction of radiant flux
• Incoming (PARin)
• Reflected (PARR )
• Transmitted (ART )
• Soil Reflected (PARSR)
fAPAR = (PARin – PARR – PART + PARSR) / PARin
How Instruments See Appropriate wavelength coverage
How Instruments See
Individual measurements of incoming and outgoing long and shortwave radiation
KZ CN4 net radiometerKZ CNR1 net radiometer
How Instruments See
Incoming and outgoing all wave components
KZ CNR2 net radiometer(Discontinued)
How Instruments See
Single measurement of net radiation
KZ NR-Lite net radiometer
REBS Q*7.1 net radiometer
How Instruments See
Hemispherical vs Field of View (FOV) Spatial coverage
Appropriate wavelength coverage
Clear View :• Obstructions• Shadows• Mounting Frame• Single Plant vs Canopy
How is Instrument Installed? Mounting Frame
How is Instrument Installed? Mounting Frame Direction
How is Instrument Installed? Direction : North vs South
How is Instrument Installed? Direction : Nadir vs Off-Nadir
How is Instrument Installed? Mounting Frame Direction :
• North vs South• Nadir (straight down) vs Off-nadir (45° )
Height Above Canopy ????
How is Instrument Installed? Height Above Canopy:
• Static height
How Big is the Spot?
10 m
How is Instrument Installed? Mounting Frame Direction :
• North vs South• Nadir (straight down) vs Off-nadir (45° )
Height Above Canopy:• Constant height above canopy• Static height
Power Requirement
Row Crop vs Homogenous Canopy
Maintenance Requirements
Cleaning of Instruments
Maintenance Requirements
Cleaning of InstrumentsBird damage and droppings Rodent damage to wires
Maintenance & Repair
Rodent Damage
Maintenance Requirements Desiccant Checks
Maintenance Requirements
Cleaning of Instruments Desiccant Checks Leveling
Maintenance Requirements Level 2o off Level
Calibration
Factory and “in house” Calibrations
Frequency
Wavelength Characterization
Calibration
Factory and “in-house” Calibration
References
Eppley PSP pyranometers and Li-Cor Pyranometers
What Is A “Measurement”?
Output – millivolt and voltsSimple conversion to radiant flux by
multiplying output times calibration coefficient
Response time
Frequency of measurement - ?????
Instantaneous vs Average
Calibration
Factory and “in-house” Calibration
References
• Location of Instruments• Wavebands of Instruments• Calibration of Instruments• Level/Cleanliness• Rounding Errors
Net Radiation Balance
Rn (Calculated) = 458.11 W m-2 | Rn (Measured) = 423.85 W m-2
What Caused the Difference?
Questions?
What Instruments See How to Install Instruments How to Maintain the Instruments
Mark Mesarch
229D Hardin Hall 402.472.5904 or [email protected] Assignment 4 on Blackboard (DUE: Sept 30)