Pressure responses of portable CO2 concentration sensors

Here, we investigated the pressure response of fi ve different models of portable CO 2 infrared sensors: GMP343 (Vaisala Oyj, Finland), ADC LCA-2 (The ADC Bioscientifi c Ltd., UK), and three different EGMs (PP Systems, UK). In the pressure range of 750–1000 hPa, we found that the analysers function systematically in an individual manner and the original pressure corrections that the manufacturers have provided are inaccurate from a few to tens of ppm. Therefore, we determined new empirical pressure correction functions for each sensor. The resulting corrections perform better than the original ones in the pressure, CO 2 concentration (370–490 ppm), temperature (5–21 °C) and water-vapour (4–11 g m) range of this study. However, since the individual analysers had different pressure responses, we recommend that each individual instrument be tested in cases where changes in pressure may affect the results.