FAQs Frequently Asked Questions About our Products and Solutions

When should the enhanced barometer be selected over the basic barometer for the EC150 or IRGASON^®?

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.

• The basic barometer has an accuracy of ±1.5 kPa between 0° and 50°C.  Below 0°, the error increases linearly to ±3.7 kPa at -30°C.
• The enhanced barometer offers an accuracy of ±0.15 kPa (-30° to +50°C).

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.

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