Stable Isotopologues

STABLE ISOTOPOLOGUES

Isotopologues are molecules containing one or multiple rare isotope(s). For the CloudRoots project, the main isotopologues of CO₂ and H₂O will be measured and modeled. Combining both methods will enable us to differentiate whether the soil or the vegetation are the source of a water vapor or the carbon dioxide fluxes. As isotopologues contain rare isotopes, their abundance is low, which makes them difficult to measure. In the CloudRoots project we will use state-of-the-art closed path laser spectrometers to measure isotopologue concentrations in the field. Such a device uses the absorption of laser light at certain frequencies to measure the concentration of specific isotopologues. To this end, we use an Aerodyne TILDAS-CS to observe ¹²CO₂, ¹³CO₂, C¹⁷OO and C¹⁸OO, and a Picarro L2030i (flight modified) for measuring H₂¹⁶O, DHO and H₂¹⁸O. The laser spectrometers allow for high frequency measurements at 10Hz and 5Hz respectively. Our goal is to couple these high frequency isotope data to turbulence measurements using an Eddy covariance system or a Scintillometer in order to derive field-scale isofluxes.