LI-COR LI-8100A - Page 7

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Auxiliary Sensor Interface Terminals ........................................................................................ 2-10
Connecting Sensors to the Auxiliary Sensor Interface .............................................................. 2-12
Connecting Soil Moisture/Temperature Probes to the Auxiliary Sensor Interface ................... 2-15
Important Note on Wire Insertion............................................................................................. 2-18
Using Soil Collars............................................................................................................................. 2-18
Construction of Soil Collars ...................................................................................................... 2-18
Installing and Using Soil Collars ............................................................................................... 2-19
Insertion Depth.......................................................................................................................... 2-19
Measuring the Chamber Offset ................................................................................................. 2-20
Placement of Soil Temperature and Moisture Probes ..................................................................... 2-21
References ........................................................................................................................................ 2-22
Section 3. Measurement Quick Start
About LI-8100A Data Files ................................................................................................................ 3-7
Section 4. Theory of Operation
Measuring Carbon Dioxide Flux from the Soil.................................................................................. 4-1
Deriving the Flux Equation: The Model ............................................................................................ 4-2
Calculating the Flux from Measured Data......................................................................................... 4-5
Relationship Between the Model Equation (4-10) and Empirical Equation (4-13) ........................... 4-8
Correcting for Initial CO
2
Concentrations That Differ Between Measurements............................... 4-8
Evaluation of Other Methods for Computing Soil CO
2
Efflux........................................................... 4-8
Effects of High Chamber CO
2
Concentrations .................................................................................. 4-9
Using the 8100-104C for Net Carbon Exchange (NCE) .................................................................... 4-11
Shading Effects............................................................................................................................. 4-14
Measuring PAR with the 8100-104C .......................................................................................... 4-15
References .......................................................................................................................................... 4-16
Section 5. User Calibration
Introduction ........................................................................................................................................ 5-1
CO
2
and H
2
O Gas Standards ............................................................................................................ 5-2
CO
2
and H
2
O Zero ..................................................................................................................... 5-2
CO
2
Span(s) ................................................................................................................................. 5-2
H
2
O Span .................................................................................................................................... 5-3
Setting Zero: CO
2
and H
2
O............................................................................................................... 5-3
Using a Calibrated Tank of Zero Gas ......................................................................................... 5-3
Using Chemical Scrubbers.......................................................................................................... 5-4
Setting the Span: CO
2
........................................................................................................................ 5-4