NRES 408/808
Instrumentation Demonstration -Radiation Instrumentation
Mark Mesarch
229D Hardin Hall
472-5904 or mmesarch1@unl.edu
Office Hours
 Homework
Assignment 4 on Blackboard
 Questions:
 Phone:
402.472.5904
 e-mail: mmesarch1@unl.edu
 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
Where
Rn = Net Radiation
RSW = Short wave Incoming
RSW = Short wave Outgoing
RLW = Long wave Incoming
RLW = Long wave Outgoing
Net Radiation Budget
Calculated Net Radiaion and Individual Components
Grass Mulch on 9/14/2005
Radiant Energy Flux ( W m-2)
900
800
700
600
500
400
300
200
100
0
-100
-200
0
4
8
12
16
20
Time ( Decimal Hour )
Rsw In
Rsw Out
Rlw In
Rlw Out
Rn Calculated
24
Net Radiation Budget
Measured
Net Radiation Budget
Rn = RSW - RSW + RLW- RLW
Where
Rn = Net Radiation
RSW = Short wave Incoming
RSW = Short wave Outgoing
RLW = Long wave Incoming
RLW= Long wave Outgoing
Net Radiation Budget
Rn = RSW - RSW + RLW- RLW
At 13:30 on September 14
RSW = 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
Net Radiation Balance
(Calculated) = 458.11 W m-2
 Rn (Measured) = 423.85 W m-2
 What Caused the Difference?
 Rn
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
Hemispherical
24o Field of View
How Instruments See
Hemispherical
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 See
Spatial 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 CNR1 net radiometer
KZ CN4 net radiometer
How Instruments See
 Incoming
and outgoing all wave components
KZ CNR2 net radiometer
(Discontinued)
How Instruments See
 Single
measurement of net radiation
REBS Q*7.1 net radiometer
KZ NR-Lite 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

Direction
Frame
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


Row Crop vs Homogenous Canopy
Power Requirement
Maintenance Requirements
 Cleaning
of Instruments
Maintenance Requirements
 Cleaning
of Instruments
Bird 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 volts
 Simple
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
Net Radiation Balance
Rn (Calculated) = 458.11 W m-2 | Rn (Measured) = 423.85 W m-2
 What
•
•
•
•
•
Caused the Difference?
Location of Instruments
Wavebands of Instruments
Calibration of Instruments
Level/Cleanliness
Rounding Errors
Questions?
 What
Instruments See
 How to Install Instruments
 How to Maintain the Instruments
Mark Mesarch
 229D
Hardin Hall
 402.472.5904 or mmesarch1@unl.edu
 Assignment 4 on Blackboard (DUE: Sept 30)