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FTIR measurements at Porto Velho, Brazil
The FTIR technique enables the simultaneous measurement of many atmospheric species of biogenic origin and biomass fires, such as methane, carbon monoxide and numerous volatile organic compounds (VOCs) like ethane, acetylene, formaldehyde, methanol and formic acid.
Some species are more difficult to detect because their spectral signature is very weak. Such is the case of isoprene, the most abundant VOC in the atmosphere. Recently, this species was detected for the first time using the FTIR technique (Wells et al., 2022) thanks to our measurements in Porto Velho, where the concentration of isoprene is one of the highest in the world.
Satellite validation
Our unique isoprene data have enabled the validation of a new CrIS (Cross-track Infrared Sounder) satellite product, which is essential before these data can be used in atmospheric chemistry models. Isoprene is also difficult to measure from space and this validation shows a systematic bias of 20-50% in satellite measurements (Wells et al., 2022).
Satellites rarely have a constant bias. It is often proportional to the concentration of the species measured. Knowing this proportionality makes it possible to correct satellite measurements before integrating them into inversion models that use satellites to optimize our planet's emissions.
One example is the validation of formaldehyde on the TROPOMI and OMI satellites using FTIR data (Vigouroux et al., 2020). It has been used to improve optimization of VOC emissions (Oomen et al., 2024, Müller et al., 2024).
As our Porto Velho station has very high concentrations of species emitted by the Amazon rainforest (VOCs, ammonia, ....), it enables us to better quantify this bias proportionality. In addition to formaldehyde, our Porto Velho data have more recently been used to validate carbon monoxide and ammonia from IASI (CCI+ ozone precursors project), or other VOCs measured by CrIS (Wells et al., 2025).
