A modular field system enabling cavity ring-down spectroscopy of in-situ vapor observations in harsh environments: The ISE-CUBE system.

Over the last two decades, cavity ring-down spectroscopy (CRDS) has allowed for increasingly widespread, in-situ observations of trace gases in vapor, including the stable isotopic composition of water vapor. However, in-situ observation in harsh environments pose a particular challenge, as these CRDS analyzers are designed for use in a conventional laboratory. As such, field deployments typically enclose the instrument in a "quasi-laboratory". These deployments often involve substantial logistical effort, 5 in addition to potentially affecting the measurement site, such as impacting flow conditions around near-surface processes. We designed the ISE-CUBE system as a modular CRDS deployment system for stable water isotope measurements, with a specific focus on observing near-surface processes. We tested the system during a two-week field campaign during Feb-March 2020 in Ny-Ålesund, Svalbard, Norway, with ambient temperatures down to -30 C, and winds gusting over 20ms-1. The system functioned suitably throughout the campaign, with field periods exhibiting only a minimal decrease in isotopic 10 measurement precision (18O: 0.06? & D: 0.47?) as compared to optimal laboratory operation. Having proven itself in challenging arctic conditions, the ISE-CUBE system can be readily adapted to the particular needs of future stable water isotope researchers, wherever their research aims might take them. [ABSTRACT FROM AUTHOR]