AP200 CO2/H2O Atmospheric Profile System
Complete, Integrated System
Preprogrammed and low power
weather applications water applications energy applications gas flux and turbulence applications infrastructure applications soil applications


The AP200 is a complete, integrated CO2 and H2O atmospheric profile system. It measures carbon dioxide (CO2) and water vapor (H2O) concentration from up to eight intakes, which are normally spaced along the height of a tower to give a vertical profile. The AP200 is often used in conjunction with an eddy-covariance system to measure the storage term and give a more complete measure of the surface gas exchange.

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Benefits and Features

  • Fully integrated system
  • Requires only 13 W (average at 25°C and 12 Vdc)
  • Contains a Campbell Scientific CR1000X Measurement and Control Datalogger
  • Automatically performs CO2 zero and span
  • Automated temperature and pressure control
  • Data logger program included


<dl><dt>Typical AP200 Installation</dt> <dd>1-27693 Heated Sample Intake Assemblies (from 4 up to 8)</dd>
<dd>2-9922 20 AWG Power Cable</dd>
<dd>3-28547 AP200 System Enclosure</dd>
<dd>4-15702 Tubing</dd>
<dd>5-Zero/Span Tanks and Regulators (not included)</dd>
<dd>6-Instrument Tower (sold separately)</dd></dl>

Detailed Description



  • CO2 concentration at each intake
  • H2O concentration at each intake
  • System diagnostic word


  • Sample flow rate
  • Sample cell pressure
  • Sample cell temperature
  • Other control variables

Note: Contact the Micromet Group at Campbell Scientific for questions or updates regarding the datalogger program.


System Enclosure

Operating Temperature -30° to +45°C
Power Requirements
  • 10 to 16 Vdc (voltage)
  • 13 W (average power at 25°C)
    Average power varies from 12.5 W above +35°C to 22.5 W at -30°C.
  • 3.75 A (45 W) maximum power (cold startup)
Dimensions 52.1 x 44.5 x 29.7 cm (20.5 x 17.5 x 11.7 in.)
  • 15.9 kg (35 lb) for AP200 base model
  • 1 kg (2.3 lb) for LI-850
  • 272 g (10 oz) for CR1000KD
  • 154 g (5.4 oz) for CFM100/NL116

Pump Module

Pump Type Dual-head diaphragm pump with a brushless dc motor
Mounting Mounted in an insulated, temperature-controlled box inside system enclosure
Control Pumping speed is automatically controlled to maintain the pump inlet pressure at the set point
Maximum Pumping Speed 9.0 liters per minute (LPM)
Pressure Sensor Range 15.0 to 115.0 kPa
Heater 8.0 W (turns on/off at 2°C)
Warm-up Time ~50 min (from -30° to +2°C)
Fan 0.7 W (turns on at 50°C and off at 45°C)

Valve Manifold

Mounting Mounted inside system enclosure
Inlets Eight air sample inlets plus one inlet for zero, one inlet for CO2 span, and one inlet for H2O span
Connections 0.25-in Swagelok
Mass Flow Sensor 0 to 1.0 standard liters per minute (SLPM)
Heater 8.0 W (turns on/off at 5°C)
Warm-up Time ~20 min (from -30° to +4°C)
Fan 0.7 W (turns on at 45°C and off at 43°C)

Intake Assembly

Filter 1.0-in diameter, sintered stainless-steel disk filter, 10-micron pore size
Orifice Heater 2 kohm (0.07 W at 12 Vdc)
Mixing Volume 750 mL
Sample Connection 0.25 in. Swagelok
Number of Connections for Heater Cable Entry Seals 3 (1 in, 2 out)
Cable Diameter for Heater Cable Entry Seals 2.8 to 6.6 mm (0.11 to 0.26 in.)
Wire Diameter for Heater Cable Screw Terminals 26 to 12 AWG
Wire Stripping Length for Heater Cable Screw Terminals 5.0 mm (0.2 in.)
Screw Tightening Torque for Heater Cable Screw Terminals 0.4 N•m
Orifice Inside Diameter 0.178 mm (0.007 in.)
Dimensions 31 x 12.5 x 19 cm (12 x 5 x 7.5 in.)
Weight 1.4 kg (3.1 lb)


AP200 CR1000 Program v.2.01 (31.3 KB) 12-01-2021

AP200 CR1000(X) Program.

Compatible with the LI-850.

Note: For those with the LI-840 contact Campbell Scientific for compatible code.

View Revision History

Device Configuration Utility v.2.26 (44.8 MB) 16-03-2021

A software utility used to download operating systems and set up Campbell Scientific hardware. Also will update PakBus Graph and the Network Planner if they have been installed previously by another Campbell Scientific software package.

Supported Operating Systems:

Windows 10, 8.1, 8, and 7 (Both 32 and 64 bit)

View Revision History

Frequently Asked Questions

Number of FAQs related to AP200: 52

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  1. Numbering this way helps reduce the time skew between measurements of the intakes. To illustrate this, consider a parcel of air that moves through the intake tubes at approximately 0.5 m/s. If the longest tube is 60 m longer than the shortest tube, its travel time is two minutes longer than the shortest tube. Sampling from the shortest tube first means that the air samples enter each tube at the same time.

  2. It depends on the type of chambers. The AP200 requires a constant flow of sample air for each intake, so it will not work with small chambers that require the air sample to recirculate. However, it might be possible to use the AP200 with chambers that allow a continuous sample flow to be extracted.
  3. Yes. Contact Campbell Scientific for a quote to have an application engineer install the system.
  4. The LI-840A does not require any routine maintenance if it is used as described in the AP200 and LI-840A manuals.

  5. The filters on the intake assemblies should keep the IRGA sample cell clean for a long time. A long-term test of an AP200 outside Logan, UT, showed that the sample cell was still clean after a year of operation. However, if it becomes difficult to span the LI-840A, if there is excessive noise, or if there is excessive drift in either the CO2 or H2O zero, then it may be necessary to clean the sample cell. Refer to the instructions in the LI-840A user manual.
  6. No. If the LI-840A requires repair or recalibration, return it to LI-COR.
  7. The automatic zero/span function of the AP200 is designed to do both a zero and a CO2 span. However, it is possible to disable the CO2 span and do only a zero. To do this, set public variable CO2_SPAN_PPM =0.

  8. Configure the AP200 to set the zero and CO2 span. This will provide better accuracy than simply measuring the zero and span tanks and doing a correction in post-processing.
  9. The CO2 span is done in terms of the concentration, which does not change with pressure. Zero air has no CO2 or H2O, so pressure has no effect.

    In contrast, the H2O span is done in terms of the dewpoint, which does depend on pressure. The dewpoint generator pushes an air stream at ambient pressure, saturated at the dewpoint temperature setting, to the AP200 inlet. The AP200 pulls a subsample of this air stream into the IRGA at low pressure. Changing the pressure does not change the concentration of H2O, but it does change the dewpoint. Because of this pressure change, the AP200 must calculate the dewpoint in the sample cell (at the reduced pressure). To do this calculation, the AP200 must know the ambient pressure (pressure in the dewpoint generator) and the pressure in the sample cell. The equations for these calculations are provided in Appendix I of the AP200 Instruction Manual.

Case Studies

China: Flux Cooperation
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The Warra long-term ecological research (LTER) site located in Southwestern Tasmania was founded in 1995 to monitor......read more

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