Articles | Volume 18, issue 21
https://doi.org/10.5194/amt-18-6465-2025
© Author(s) 2025. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
Special issue:
https://doi.org/10.5194/amt-18-6465-2025
© Author(s) 2025. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
Research article
| Highlight paper
| 
12 Nov 2025
Research article | Highlight paper |
| 12 Nov 2025
| 12 Nov 2025
The airborne chicago water isotope spectrometer: an integrated cavity output spectrometer for measurements of the HDO ∕ H2O isotopic ratio in the Asian Summer Monsoon
Benjamin W. Clouser
CORRESPONDING AUTHOR
Department of Physics, University of Chicago, Chicago, IL, USA
Department of the Geophysical Sciences, University of Chicago, Chicago, IL, USA
Laszlo C. Sarkozy
Department of the Geophysical Sciences, University of Chicago, Chicago, IL, USA
Clare E. Singer
Department of the Geophysical Sciences, University of Chicago, Chicago, IL, USA
Carly C. KleinStern
Department of Physics, University of Chicago, Chicago, IL, USA
Adrien Desmoulin
Department of the Geophysical Sciences, University of Chicago, Chicago, IL, USA
Dylan Gaeta
Department of the Geophysical Sciences, University of Chicago, Chicago, IL, USA
Sergey Khaykin
LATMOS/IPSL, UVSQ, Sorbonne Université, CNRS, Guyancourt, France
Stephen Gabbard
National Center for Atmospheric Research, Boulder, CO, USA
Stephen Shertz
National Center for Atmospheric Research, Boulder, CO, USA
Elisabeth J. Moyer
CORRESPONDING AUTHOR
Department of the Geophysical Sciences, University of Chicago, Chicago, IL, USA
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Water molecules comes in several varieties, of which H216O is the most common. These varieties behave differently enough under freezing to create strong changes in the ratio of heavy to light water molecules. Here we compare observations of these ratios from satellites and high-altitude airborne instruments. These observations provide information about how air reaches the upper parts of the atmosphere, so it is important to reconcile difference between different modes of observations.
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Clare E. Singer, Benjamin W. Clouser, Sergey M. Khaykin, Martina Krämer, Francesco Cairo, Thomas Peter, Alexey Lykov, Christian Rolf, Nicole Spelten, Armin Afchine, Simone Brunamonti, and Elisabeth J. Moyer
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Sergey M. Khaykin, Elizabeth Moyer, Martina Krämer, Benjamin Clouser, Silvia Bucci, Bernard Legras, Alexey Lykov, Armin Afchine, Francesco Cairo, Ivan Formanyuk, Valentin Mitev, Renaud Matthey, Christian Rolf, Clare E. Singer, Nicole Spelten, Vasiliy Volkov, Vladimir Yushkov, and Fred Stroh
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Deep convection overshooting the stratosphere's contribution to the global stratospheric water budget is still being quantified. We ran three different cloud-resolving simulations of an observed case of overshoots in Bauru during the TRO-Pico balloon campaign in the context of upscaling the impact of overshoots at a large scale. These simulations, which have been validated with balloon-borne and S-band radar measurements, shed light on the local-scale variability and composition of overshoots.
Robin Wing, Sophie Godin-Beekmann, Wolfgang Steinbrecht, Thomas J. McGee, John T. Sullivan, Sergey Khaykin, Grant Sumnicht, and Laurence Twigg
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Lars E. Kalnajs, Sean M. Davis, J. Douglas Goetz, Terry Deshler, Sergey Khaykin, Alex St. Clair, Albert Hertzog, Jerome Bordereau, and Alexey Lykov
Atmos. Meas. Tech., 14, 2635–2648, https://doi.org/10.5194/amt-14-2635-2021, https://doi.org/10.5194/amt-14-2635-2021, 2021
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This work introduces a novel instrument system for high-resolution atmospheric profiling, which lowers and retracts a suspended instrument package beneath drifting long-duration balloons. During a 100 d circumtropical flight, the instrument collected over a hundred 2 km profiles of temperature, water vapor, clouds, and aerosol at 1 m resolution, yielding unprecedented geographic sampling and vertical resolution measurements of the tropical tropopause layer.
Britton B. Stephens, Eric J. Morgan, Jonathan D. Bent, Ralph F. Keeling, Andrew S. Watt, Stephen R. Shertz, and Bruce C. Daube
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We describe methods used to make high-precision global-scale airborne measurements of atmospheric oxygen concentrations over a period of 20 years in order to study the global carbon cycle. Our techniques include an in situ vacuum ultraviolet absorption instrument and a pressure- and flow-controlled, cryogenically dried, glass flask sampler. We have deployed these instruments in 15 airborne research campaigns spanning from the Earth’s surface to the lower stratosphere and from pole to pole.
Masatomo Fujiwara, Tetsu Sakai, Tomohiro Nagai, Koichi Shiraishi, Yoichi Inai, Sergey Khaykin, Haosen Xi, Takashi Shibata, Masato Shiotani, and Laura L. Pan
Atmos. Chem. Phys., 21, 3073–3090, https://doi.org/10.5194/acp-21-3073-2021, https://doi.org/10.5194/acp-21-3073-2021, 2021
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Lidar aerosol particle measurements in Japan during the summer of 2018 were found to detect the eastward extension of the Asian tropopause aerosol layer from the Asian summer monsoon anticyclone in the lower stratosphere. Analysis of various other data indicates that the observed enhanced particle levels are due to eastward-shedding vortices from the anticyclone, originating from pollutants emitted in Asian countries and transported vertically by convection in the Asian summer monsoon region.
Cited articles
ACCLIP Team: ACCLIP Campaign Data, National Aeronautics and Space Administration [data set], https://www-air.larc.nasa.gov/cgi-bin/ArcView/acclip (last access: 21 February 2024), 2022. a
Allen, N.: nthallen/icosfit: icosfit V4.3.0, Zenodo [code], https://doi.org/10.5281/zenodo.6362473, 2022. a, b
Bennett, H. E. and Porteus, J. O.: Relation Between Surface Roughness and Specular Reflectance at Normal Incidence, J. Opt. Soc. Am., 51, 123–129, https://doi.org/10.1364/JOSA.51.000123, 1961. a
Bernath, P. F., McElroy, C. T., Abrams, M. C., Boone, C. D., Butler, M., Camy-Peyret, C., Carleer, M., Clerbaux, C., Coheur, P.-F., Colin, R., DeCola, P., DeMazière, M., Drummond, J. R., Dufour, D., Evans, W. F. J., Fast, H., Fussen, D., Gilbert, K., Jennings, D. E., Llewellyn, E. J., Lowe, R. P., Mahieu, E., McConnell, J. C., McHugh, M., McLeod, S. D., Michaud, R., Midwinter, C., Nassar, R., Nichitiu, F., Nowlan, C., Rinsland, C. P., Rochon, Y. J., Rowlands, N., Semeniuk, K., Simon, P., Skelton, R., Sloan, J. J., Soucy, M.-A., Strong, K., Tremblay, P., Turnbull, D., Walker, K. A., Walkty, I., Wardle, D. A., Wehrle, V., Zander, R., and Zou, J.: Atmospheric Chemistry Experiment (ACE): Mission overview, Geophysical Research Letters, 32, https://doi.org/10.1029/2005GL022386, 2005. a
Bolot, M., Legras, B., and Moyer, E. J.: Modelling and interpreting the isotopic composition of water vapour in convective updrafts, Atmos. Chem. Phys., 13, 7903–7935, https://doi.org/10.5194/acp-13-7903-2013, 2013. a
Brewer, A. W.: Evidence for a world circulation provided by the measurements of helium and water vapour distribution in the stratosphere, Quarterly Journal of the Royal Meteorological Society, 75, 351–363, https://doi.org/10.1002/qj.49707532603, 1949. a
Briggs, R. M., Frez, C., Bagheri, M., Borgentun, C. E., Gupta, J. A., Witinski, M. F., Anderson, J. G., and Forouhar, S.: Single-mode 2.65 μm InGaAsSb/AlInGaAsSb laterally coupled distributed-feedback diode lasers for atmospheric gas detection, Opt. Express, 21, 1317–1323, https://doi.org/10.1364/OE.21.001317, 2013. a
Bucci, S., Legras, B., Sellitto, P., D'Amato, F., Viciani, S., Montori, A., Chiarugi, A., Ravegnani, F., Ulanovsky, A., Cairo, F., and Stroh, F.: Deep-convective influence on the upper troposphere–lower stratosphere composition in the Asian monsoon anticyclone region: 2017 StratoClim campaign results, Atmos. Chem. Phys., 20, 12193–12210, https://doi.org/10.5194/acp-20-12193-2020, 2020. a
Clair, J. M. S., Hanisco, T. F., Weinstock, E. M., Moyer, E. J., Sayres, D. S., Keutsch, F. N., Kroll, J. H., Demusz, J. N., Allen, N. T., Smith, J. B., Spackman, J. R., and Anderson, J. G.: A new photolysis laser-induced fluorescence instrument for the detection of H2O and HDO in the lower stratosphere, Review of Scientific Instruments, 79, 064101, https://doi.org/10.1063/1.2940221, 2008. a
Clouser, B. W., Sarkozy, L., and Moyer, E. J.: Improved light collection in OA-ICOS cells using non-axially-symmetric optics, Appl. Opt., 57, 6252–6259, https://doi.org/10.1364/AO.57.006252, 2018. a, b, c
Clouser, B. W., Lamb, K. D., Sarkozy, L. C., Habig, J., Ebert, V., Saathoff, H., Möhler, O., and Moyer, E. J.: No anomalous supersaturation in ultracold cirrus laboratory experiments, Atmos. Chem. Phys., 20, 1089–1103, https://doi.org/10.5194/acp-20-1089-2020, 2020. a
Clouser, B. W., KleinStern, C. C., Desmoulin, A., Singer, C. E., St. Clair, J. M., Hanisco, T. F., Sayres, D. S., and Moyer, E. J.: A systematic comparison of ACE-FTS δD retrievals with airborne in situ sampling, EGUsphere [preprint], https://doi.org/10.5194/egusphere-2025-1190, 2025. a
Corti, T., Luo, B. P., de Reus, M., Brunner, D., Cairo, F., Mahoney, M. J., Martucci, G., Matthey, R., Mitev, V., dos Santos, F. H., Schiller, C., Shur, G., Sitnikov, N. M., Spelten, N., Vössing, H. J., Borrmann, S., and Peter, T.: Unprecedented evidence for deep convection hydrating the tropical stratosphere, Geophysical Research Letters, 35, https://doi.org/10.1029/2008GL033641, 2008. a
Danielsen, E. F.: A dehydration mechanism for the stratosphere, Geophysical Research Letters, 9, 605–608, https://doi.org/10.1029/GL009i006p00605, 1982. a
Diskin, G. S., Podolske, J. R., Sachse, G. W., and Slate, T. A.: Open-path airborne tunable diode laser hygrometer, in: Diode Lasers and Applications in Atmospheric Sensing, edited by: Fried, A., International Society for Optics and Photonics, SPIE, 4817, 196–204, https://doi.org/10.1117/12.453736, 2002. a
Dyroff, C., Fütterer, D., and Zahn, A.: Compact diode-laser spectrometer ISOWAT for highly sensitive airborne measurements of water-isotope ratios, Applied Physics B, 98, 537–548, https://doi.org/10.1007/s00340-009-3775-6, 2010. a
Farmer, C. B.: High resolution infrared spectroscopy of the Sun and the Earth's atmosphere from space, Microchimica Acta, 93, 189–214, https://doi.org/10.1007/BF01201690, 1987. a
Gasparini, B., Sullivan, S. C., Sokol, A. B., Kärcher, B., Jensen, E., and Hartmann, D. L.: Opinion: Tropical cirrus – from micro-scale processes to climate-scale impacts, Atmos. Chem. Phys., 23, 15413–15444, https://doi.org/10.5194/acp-23-15413-2023, 2023. a
Gettelman, A., Kinnison, D. E., Dunkerton, T. J., and Brasseur, G. P.: Impact of monsoon circulations on the upper troposphere and lower stratosphere, Journal of Geophysical Research: Atmospheres, 109, https://doi.org/10.1029/2004JD004878, 2004. a
Gordon, I., Rothman, L., Hill, C., Kochanov, R., Tan, Y., Bernath, P., Birk, M., Boudon, V., Campargue, A., Chance, K., Drouin, B., Flaud, J.-M., Gamache, R., Hodges, J., Jacquemart, D., Perevalov, V., Perrin, A., Shine, K., Smith, M.-A., Tennyson, J., Toon, G., Tran, H., Tyuterev, V., Barbe, A., Császár, A., Devi, V., Furtenbacher, T., Harrison, J., Hartmann, J.-M., Jolly, A., Johnson, T., Karman, T., Kleiner, I., Kyuberis, A., Loos, J., Lyulin, O., Massie, S., Mikhailenko, S., Moazzen-Ahmadi, N., Müller, H., Naumenko, O., Nikitin, A., Polyansky, O., Rey, M., Rotger, M., Sharpe, S., Sung, K., Starikova, E., Tashkun, S., Auwera, J. V., Wagner, G., Wilzewski, J., Wcisło, P., Yu, S., and Zak, E.: The HITRAN2016 molecular spectroscopic database, Journal of Quantitative Spectroscopy and Radiative Transfer, 203, 3–69, https://doi.org/10.1016/j.jqsrt.2017.06.038, 2017a. a
Gordon, I., Rothman, L., Hargreaves, R., Hashemi, R., Karlovets, E., Skinner, F., Conway, E., Hill, C., Kochanov, R., Tan, Y., Wcisło, P., Finenko, A., Nelson, K., Bernath, P., Birk, M., Boudon, V., Campargue, A., Chance, K., Coustenis, A., Drouin, B., Flaud, J., Gamache, R., Hodges, J., Jacquemart, D., Mlawer, E., Nikitin, A., Perevalov, V., Rotger, M., Tennyson, J., Toon, G., Tran, H., Tyuterev, V., Adkins, E., Baker, A., Barbe, A., Canè, E., Császár, A., Dudaryonok, A., Egorov, O., Fleisher, A., Fleurbaey, H., Foltynowicz, A., Furtenbacher, T., Harrison, J., Hartmann, J., Horneman, V., Huang, X., Karman, T., Karns, J., Kassi, S., Kleiner, I., Kofman, V., Kwabia–Tchana, F., Lavrentieva, N., Lee, T., Long, D., Lukashevskaya, A., Lyulin, O., Makhnev, V., Matt, W., Massie, S., Melosso, M., Mikhailenko, S., Mondelain, D., Müller, H., Naumenko, O., Perrin, A., Polyansky, O., Raddaoui, E., Raston, P., Reed, Z., Rey, M., Richard, C., Tóbiás, R., Sadiek, I., Schwenke, D., Starikova, E., Sung, K., Tamassia, F., Tashkun, S., Vander Auwera, J., Vasilenko, I., Vigasin, A., Villanueva, G., Vispoel, B., Wagner, G., Yachmenev, A., and Yurchenko, S.: The HITRAN2020 molecular spectroscopic database, Journal of Quantitative Spectroscopy and Radiative Transfer, 277, 107949, https://doi.org/10.1016/j.jqsrt.2021.107949, 2022. a, b
Gordon, I. E., Rothman, L. S., Hill, C., Kochanov, R. V., Tan, Y., Bernath, P. F., Birk, M., Boudon, V., Campargue, A., Chance, K. V., Drouin, B. J., Flaud, J.-M., Gamache, R. R., Hodges, J. T., Jacquemart, D., Perevalov, V. I., Perrin, A., Shine, K. P., Smith, M.-A. H., Tennyson, J., Toon, G. C., Tran, H., Tyuterev, V. G., Barbe, A., Császár, A. G., Devi, V. M., Furtenbacher, T., Harrison, J. J., Hartmann, J.-M., Jolly, A., Johnson, T. J., Karman, T., Kleiner, I., Kyuberis, A. A., Loos, J., Lyulin, O. M., Massie, S. T., Mikhailenko, S. N., Moazzen-Ahmadi, N., Müller, H. S. P., Naumenko, O. V., Nikitin, A. V., Polyansky, O. L., Rey, M., Rotger, M., Sharpe, S. W., Sung, K., Starikova, E., Tashkun, S. A., Vander Auwera, J., Wagner, G., Wilzewski, J., Wcisło, P., Yu, S. and Zak, E. J. : The HITRAN2016 Molecular Spectroscopic Database, Journal of Quantitative Spectroscopy and Radiative Transfer, https://doi.org/10.1016/J.JQSRT.2017.06.038, 2017b. a
Haladay, T. and Stephens, G.: Characteristics of tropical thin cirrus clouds deduced from joint CloudSat and CALIPSO observations, Journal of Geophysical Research: Atmospheres, 114, https://doi.org/10.1029/2008JD010675, 2009. a
Hanisco, T. F., Moyer, E. J., Weinstock, E. M., Clair, J. M. S., Sayres, D. S., Smith, J. B., Lockwood, R., Anderson, J. G., Dessler, A. E., Keutsch, F. N., Spackman, J. R., Read, W. G., and Bui, T. P.: Observations of deep convective influence on stratospheric water vapor and its isotopic composition, Geophysical Research Letters, 34, https://doi.org/10.1029/2006GL027899, 2007. a, b, c, d
Herriott, D., Kogelnik, H., and Kompfner, R.: Off-Axis Paths in Spherical Mirror Interferometers, Appl. Opt., 3, 523–526, https://doi.org/10.1364/AO.3.000523, 1964. a
Iannone, R. Q., Kassi, S., Jost, H.-J., Chenevier, M., Romanini, D., Meijer, H. A., Dhaniyala, S., Snels, M., and Kerstel, E. R.: Development and airborne operation of a compact water isotope ratio infrared spectrometer, Isotopes in Environmental and Health Studies, 45, 303–320, https://doi.org/10.1080/10256010903172715, 2009. a
Irion, F. W., Moyer, E. J., Gunson, M. R., Rinsland, C. P., Yung, Y. L., Michelsen, H. A., Salawitch, R. J., Chang, A. Y., Newchurch, M. J., Abbas, M. M., Abrams, M. C., and Zander, R.: Stratospheric observations of CH3D and HDO from ATMOS infrared solar spectra: Enrichments of deuterium in methane and implications for HD, Geophysical Research Letters, 23, 2381–2384, https://doi.org/10.1029/96GL01402, 1996. a
Kerstel, E. T., Iannone, R., Chenevier, M., Kassi, S., Jost, H.-J., and Romanini, D.: A water isotope (2H, 17O, and 18O) spectrometer based on optical feedback cavity-enhanced absorption for in situ airborne applications, Applied Physics B, 85, 397–406, 2006. a
Khaykin, S. M., Moyer, E., Krämer, M., Clouser, B., Bucci, S., Legras, B., Lykov, A., Afchine, A., Cairo, F., Formanyuk, I., Mitev, V., Matthey, R., Rolf, C., Singer, C. E., Spelten, N., Volkov, V., Yushkov, V., and Stroh, F.: Persistence of moist plumes from overshooting convection in the Asian monsoon anticyclone, Atmos. Chem. Phys., 22, 3169–3189, https://doi.org/10.5194/acp-22-3169-2022, 2022. a, b
Kloss, C., Tan, V., Leen, J. B., Madsen, G. L., Gardner, A., Du, X., Kulessa, T., Schillings, J., Schneider, H., Schrade, S., Qiu, C., and von Hobe, M.: Airborne Mid-Infrared Cavity enhanced Absorption spectrometer (AMICA), Atmos. Meas. Tech., 14, 5271–5297, https://doi.org/10.5194/amt-14-5271-2021, 2021. a
Kremser, S., Wohltmann, I., Rex, M., Langematz, U., Dameris, M., and Kunze, M.: Water vapour transport in the tropical tropopause region in coupled Chemistry-Climate Models and ERA-40 reanalysis data, Atmos. Chem. Phys., 9, 2679–2694, https://doi.org/10.5194/acp-9-2679-2009, 2009. a
Lamb, K. D., Clouser, B. W., Bolot, M., Sarkozy, L., Ebert, V., Saathoff, H., Möhler, O., and Moyer, E. J.: Laboratory measurements of HDO
Leen, J. B. and O’Keefe, A.: Optical re-injection in cavity-enhanced absorption spectroscopy, Review of Scientific Instruments, 85, 093101, https://doi.org/10.1063/1.4893972, 2014. a
Loos, J., Birk, M., and Wagner, G.: Measurement of air-broadening line shape parameters and temperature dependence parameters of H2O lines in the spectral ranges 1850–2280 cm−1 and 2390–4000 cm−1, Journal of Quantitative Spectroscopy and Radiative Transfer, 203, 103–118, https://doi.org/10.1016/j.jqsrt.2017.03.033, 2017. a
Meyer, J., Rolf, C., Schiller, C., Rohs, S., Spelten, N., Afchine, A., Zöger, M., Sitnikov, N., Thornberry, T. D., Rollins, A. W., Bozóki, Z., Tátrai, D., Ebert, V., Kühnreich, B., Mackrodt, P., Möhler, O., Saathoff, H., Rosenlof, K. H., and Krämer, M.: Two decades of water vapor measurements with the FISH fluorescence hygrometer: a review, Atmos. Chem. Phys., 15, 8521–8538, https://doi.org/10.5194/acp-15-8521-2015, 2015. a
Moyer, E. J., Irion, F. W., Yung, Y. L., and Gunson, M. R.: ATMOS stratospheric deuterated water and implications for troposphere‐stratosphere transport, Geophysical Research Letters, 23, 2385–2388, https://doi.org/10.1029/96GL01489, 1996. a
Moyer, E., Sayres, D., Engel, G., St. Clair, J., Keutsch, F., Allen, N., Kroll, J., and Anderson, J.: Design considerations in high-sensitivity off-axis integrated cavity output spectroscopy, Applied Physics B, 92, 467, https://doi.org/10.1007/s00340-008-3137-9, 2008. a, b, c
Nassar, R., Bernath, P. F., Boone, C. D., Gettelman, A., McLeod, S. D., and Rinsland, C. P.: Variability in HDO
Paul, J. B., Lapson, L., and Anderson, J. G.: Ultrasensitive absorption spectroscopy with a high-finesse optical cavity and off-axis alignment, Appl. Opt., 40, 4904–4910, https://doi.org/10.1364/AO.40.004904, 2001. a, b
Randel, W. J., Moyer, E., Park, M., Jensen, E., Bernath, P., Walker, K., and Boone, C.: Global variations of HDO and HDO
Reverdy, M., Noel, V., Chepfer, H., and Legras, B.: On the origin of subvisible cirrus clouds in the tropical upper troposphere, Atmospheric Chemistry and Physics, 12, 12081–12101, https://doi.org/10.5194/acp-12-12081-2012, 2012. a
Sarkozy, L. C., Clouser, B. W., Lamb, K. D., Stutz, E. J., Saathoff, H., Möhler, O., Ebert, V., and Moyer, E. J.: The Chicago Water Isotope Spectrometer (ChiWIS-lab): A tunable diode laser spectrometer for chamber-based measurements of water vapor isotopic evolution during cirrus formation, Review of Scientific Instruments, 91, 045120, https://doi.org/10.1063/1.5139244, 2020. a, b
Sayres, D. S., Moyer, E. J., Hanisco, T. F., Clair, J. M. S., Keutsch, F. N., O’Brien, A., Allen, N. T., Lapson, L., Demusz, J. N., Rivero, M., Martin, T., Greenberg, M., Tuozzolo, C., Engel, G. S., Kroll, J. H., Paul, J. B., and Anderson, J. G.: A new cavity based absorption instrument for detection of water isotopologues in the upper troposphere and lower stratosphere, Review of Scientific Instruments, 80, 044102, https://doi.org/10.1063/1.3117349, 2009. a, b, c
Sayres, D. S., Pfister, L., Hanisco, T. F., Moyer, E. J., Smith, J. B., Clair, J. M. S., O'Brien, A. S., Witinski, M. F., Legg, M., and Anderson, J. G.: Influence of convection on the water isotopic composition of the tropical tropopause layer and tropical stratosphere, Journal of Geophysical Research: Atmospheres, 115, https://doi.org/10.1029/2009JD013100, 2010. a
Singer, C. E., Clouser, B. W., Khaykin, S. M., Krämer, M., Cairo, F., Peter, T., Lykov, A., Rolf, C., Spelten, N., Afchine, A., Brunamonti, S., and Moyer, E. J.: Intercomparison of upper tropospheric and lower stratospheric water vapor measurements over the Asian Summer Monsoon during the StratoClim campaign, Atmos. Meas. Tech., 15, 4767–4783, https://doi.org/10.5194/amt-15-4767-2022, 2022. a, b, c, d, e, f
Sitnikov, N. M., Yushkov, V. A., Afchine, A. A., Korshunov, L. I., Astakhov, V. I., Ulanovskii, A. E., Kraemer, M., Mangold, A., Schiller, C., and Ravegnani, F.: The FLASH instrument for water vapor measurements on board the high-altitude airplane, Instruments and Experimental Techniques, 50, 113–121, https://doi.org/10.1134/S0020441207010174, 2007. a
StratoClim Team: StratoClim Campaign Data, [data set], Deutsches Zentrum fur Luft- und Raumfahrt, https://halo-db.pa.op.dlr.de/mission/101 (last access: 31 January 2022), 2021. a
Wahl, M. H. and Urey, H. C.: The Vapor Pressures of the Isotopic Forms of Water, The Journal of Chemical Physics, 3, 411–414, https://doi.org/10.1063/1.1749690, 1935. a
Webster, C. R. and Heymsfield, A. J.: Water Isotope Ratios D/H, 18O
Webster, C. R., May, R. D., Trimble, C. A., Chave, R. G., and Kendall, J.: Aircraft (ER-2) laser infrared absorption spectrometer (ALIAS) for in-situ stratospheric measurements of HCl, N2O, CH4, NO2, and HNO3, Appl. Opt., 33, 454–472, https://doi.org/10.1364/AO.33.000454, 1994. a
Werle, P., Mücke, R., and Slemr, F.: The limits of signal averaging in atmospheric trace-gas monitoring by tunable diode-laser absorption spectroscopy (TDLAS), Applied Physics B, 57, 131–139, 1993. a
Executive editor
The paper describes a new and complex instrument, gathering data on isotopic HDO/H2O ratios in the UTLS region from unique observational campaigns. The excellent accuracy of the measurements from the Airborne Chicago Water Isotope Spectrometer (ChiWIS) has the potential to enhance our understanding of the water vapour cycle, which is challenging to observe with the required accuracy.
The paper describes a new and complex instrument, gathering data on isotopic HDO/H2O ratios in...
Short summary
The water molecule comes in several different varieties, which are nearly indistinguishable in daily life. However, slight differences between the water molecule types can be exploited to achieve better scientific understanding of parts of Earth's atmosphere. In this work we describe the design, construction, and operation of an instrument meant to measure these molecules aboard research aircraft up to altitudes of 20 km.
The water molecule comes in several different varieties, which are nearly indistinguishable in...
