Campbell Scientific’s IRGASON fully integrates the open-path analyzer and sonic anemometer. Designed specifically for eddy-covariance flux measurements, the patented design is easier to install and use than separate sensors and provides increased measurement accuracy. The IRGASON simultaneously measures absolute carbon dioxide and water vapor, air temperature, barometric pressure, three-dimensional wind speed, and sonic air temperature. U.S. patent D680455
For more information about the benefits of having a co-located measurement, refer to the poster "Improved eddy flux measurements by open-path gas analyzer and sonic anemometer co-location."
The IRGASON has the following outputs:
bSpecifications are subject to change without notice.
cA temperature of 20°C and pressure of 101.325 kPa was used to convert mass density to concentration.
dAssumes the gas analzyer was properly zero and spanned using the appropriate standards; CO2 span concentration was 400 ppm; H2O span dewpoint was at 12°C (16.7 ppt); zero/span temperature was 25°C; zero/span pressure was 84 kPa; subsequent measurements made at or near the span concentration; temperature is not more than ±6°C from the zero/span temperature; and ambient temperature is within the gas analyzer operating temperature range.
eStandard deviation of calibration residuals.
fNominal conditions for precision verification test: 25°C, 86 kPa, 400 μmol/mol CO2, 12°C dewpoint, and 20 Hz bandwidth.
g0 to 3,000 μmol/mol available upon request.
hThe accuracy specification for the sonic anemometer is for wind speeds
< 30 m s-1 and wind angles between ±170°.
The CR5000 is the only retired datalogger that is compatible with the IRGASON.
EC100-Series Support Software.
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.View Update History
Number of FAQs related to IRGASON: 17
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Selecting which barometer to use is the choice of the user. There is a direct correlation between the accuracy level of the barometer and its cost.
When choosing a barometer, consider the effect of pressure accuracy on flux calculations. For sensible heat flux, the barometric pressure is used to calculate the density of air, which directly scales the sensible heat flux. Therefore, if the barometric pressure measurement is off by 1%, then the sensible heat flux will be off by 1%.
For CO2 flux, the EC150 and IRGASON report CO2 as density. Thus, the barometric pressure is not used to directly calculate the flux. However, error in pressure measurements could cause an error in CO2 flux resulting from a CO2 span. During the span procedure, the user enters the “true CO2 value” as a CO2 concentration, which is later converted to density using the barometric pressure. Consequently, the error in CO2 measurements is directly proportional to the error in the barometric pressure measurement.
Yes. A fine-wire thermocouple, such as a FW05, can be used.
The barometer and temperature sensor are needed because the IRGASON and EC150 have been calibrated at the factory over a range of temperatures (-30° to +50°C) and barometric pressures (70 to 106 kPa).
The factory calibration accounts for CO2 and H2O signal strengths down to 0.7. Therefore, to ensure quality data, windows should be cleaned before signal strengths drop below 0.7.
The EC150 and IRGASON can report a negative water concentration if enough liquid water accumulates on the optical windows. This is because the absorption spectrum of liquid water differs from that of water vapor. Typically, large rain droplets do not cause this phenomenon. Rather, misty or condensing conditions, which create a water film across the entire optical window, can cause this phenomenon. After the water film evaporates, the former measurement accuracy will be restored.
The IRGASON and EC150 may also experience some amount of drift over time. If conditions are relatively dry and it has been a long time since a zero and span has been performed on the analyzer, it is possible to report a negative water vapor concentration. In this situation, perform a zero and span of the analyzer.
The power requirement for the IRGASON or EC150 with CSAT3A is 5 W at room temperature regardless of whether it is powering up or under steady-state operation. At extreme cold or hot temperatures, the power requirement reaches 6 W.
For greatest accuracy, Campbell Scientific recommends that a zero and a span be done on the EC150 or IRGASON. However, if a span gas is difficult to obtain, at the minimum, perform a zero on the analyzer. Performing a zero will correct the majority of drift experienced by the analyzer. Follow the zero procedure in the analyzer’s manual for details.
The EC150 and IRGASON gas analyzer windows are polished, slanted at an angle, and coated with a hydrophobic material to prevent water from collecting on their surfaces. Wicks may also be used on the windows to promote capillary action and move water away from the window edges. Also, heaters in the snouts may be turned on to help minimize data loss because of precipitation and condensation events.
Campbell Scientific recommends replacing the scrubber bottles yearly. However, if the zero and span coefficients for the CO2 and H2O have drifted excessively, they may need to be replaced more often.
Factory recalibration is done on an as-needed basis. When diagnostic flags begin to appear and persist even after cleaning the analyzer and verifying its settings, a recalibration is needed. Additionally, if the performance of the analyzer has degraded, a recalibration is recommended.
One performance test is to check the absolute signal strength drift over the course of 1 year. Drift of a few percent per year is normal. If the annual signal strength drift is excessive, or if the signal strength is below 0.7 when the windows are clean, a factory recalibration is needed. Furthermore, if the ratio of the CO2 to H2O signal strength is not close to one, it may also be time for a factory recalibration.