Milestone: proof-of-concept measurements

Just over a year in the REAC-FORTE project, we have a system running to measure ozone reactivity and we brought it a few weeks ago to the SMEAR II field station for proof-of-concept measurements.

We are testing in real conditions the system that we developed based on our experience in Boulder with the group of Prof. Detlev Helmig. While in the lab the temperature and the relative humidity are quite stable, this is not the case in the forest. As the temperatures are decreasing and the relative humidity increase as autumn approaches, it is a good period to get preliminary measurements and to check that our system can run undisturbed when environmental conditions are changing.

As none of our other on-line instrument to measure the air composition (gas chromatograph coupled to a mass spectrometer) is available at this time for simultaneous measurements, we collect air samples on adsorption tubes with the help of an auto-sampler (sampling time: 4 hours). These samples are then analyzed (off-line) in our laboratory. Soon we will be comparing the ozone reactivity calculated from this known composition of the air and compare it the the total ozone reactivity measured directly with out system. Any guesses what the difference will be?

Figure 1. Left: Instrumentation to measure ozone reactivity in the FMI containter at SMEAR II. Right: auto-sampler for sampling on adsorption tubes on the roof of the FMI container at SMEAR II. (Pictures: Anssi Liikanen, CC-BY-4.0)