TY - JOUR
T1 - The airborne chicago water isotope spectrometer
T2 - an integrated cavity output spectrometer for measurements of the HDO / H2O isotopic ratio in the Asian Summer Monsoon
AU - Clouser, Benjamin W.
AU - Sarkozy, Laszlo C.
AU - Singer, Clare E.
AU - Kleinstern, Carly C.
AU - Desmoulin, Adrien
AU - Gaeta, Dylan
AU - Khaykin, Sergey
AU - Gabbard, Stephen
AU - Shertz, Stephen
AU - Moyer, Elisabeth J.
N1 - Publisher Copyright:
© 2025 Benjamin W. Clouser et al.
PY - 2025/11/12
Y1 - 2025/11/12
N2 - We describe a new version of the Chicago Water Isotope Spectrometer (ChiWIS), designed for airborne measurements of vapor-phase water isotopologues in the dry upper troposphere and lower stratosphere (UTLS) aboard research aircraft. This version of the instrument is a tunable diode laser (TDL), off-axis integrated cavity output spectrometer (OA-ICOS). The instrument was designed to measure the HDO / H2O ratio in the 2017 Asian Summer Monsoon flight aboard the M-55 Geophysica during the StratoClim campaign, and so far has also flown aboard the WB-57F in the 2021 and 2022 ACCLIP campaigns. The spectrometer scans absorption lines of both H2O and HDO near 2.647 μm wavelength in a single current sweep, and has an effective path length of 7.5 km under optimal conditions. The instrument utilizes a novel non-axially-symmetric optical component which increases the signal-to-noise ratio by a factor of 3. Ultra-polished, 4 in. (101.6 mm) diameter cavity mirrors suppress scattering losses, maximize mirror reflectivity, and yield optical fringing significantly below typical electrical noise levels. In laboratory conditions, the instrument has demonstrated a 5 s measurement precision of 3.6 ppbv and 82 pptv in H2O and HDO, respectively.
AB - We describe a new version of the Chicago Water Isotope Spectrometer (ChiWIS), designed for airborne measurements of vapor-phase water isotopologues in the dry upper troposphere and lower stratosphere (UTLS) aboard research aircraft. This version of the instrument is a tunable diode laser (TDL), off-axis integrated cavity output spectrometer (OA-ICOS). The instrument was designed to measure the HDO / H2O ratio in the 2017 Asian Summer Monsoon flight aboard the M-55 Geophysica during the StratoClim campaign, and so far has also flown aboard the WB-57F in the 2021 and 2022 ACCLIP campaigns. The spectrometer scans absorption lines of both H2O and HDO near 2.647 μm wavelength in a single current sweep, and has an effective path length of 7.5 km under optimal conditions. The instrument utilizes a novel non-axially-symmetric optical component which increases the signal-to-noise ratio by a factor of 3. Ultra-polished, 4 in. (101.6 mm) diameter cavity mirrors suppress scattering losses, maximize mirror reflectivity, and yield optical fringing significantly below typical electrical noise levels. In laboratory conditions, the instrument has demonstrated a 5 s measurement precision of 3.6 ppbv and 82 pptv in H2O and HDO, respectively.
UR - https://www.scopus.com/pages/publications/105021872891
U2 - 10.5194/amt-18-6465-2025
DO - 10.5194/amt-18-6465-2025
M3 - Article
AN - SCOPUS:105021872891
SN - 1867-1381
VL - 18
SP - 6465
EP - 6491
JO - Atmospheric Measurement Techniques
JF - Atmospheric Measurement Techniques
IS - 21
ER -