Articles | Volume 24, issue 8
https://doi.org/10.5194/acp-24-4693-2024
© Author(s) 2024. 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/acp-24-4693-2024
© Author(s) 2024. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
Research article
| 
19 Apr 2024
Research article |
| 19 Apr 2024
| 19 Apr 2024
Air mass transport to the tropical western Pacific troposphere inferred from ozone and relative humidity balloon observations above Palau
Alfred-Wegener-Institute, Helmholtz Center for Polar and Marine Research, Potsdam, Germany
Peter von der Gathen
Alfred-Wegener-Institute, Helmholtz Center for Polar and Marine Research, Potsdam, Germany
Markus Rex
Alfred-Wegener-Institute, Helmholtz Center for Polar and Marine Research, Potsdam, Germany
Institut für Physik und Astronomie, Universität Potsdam, Potsdam, Germany
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Direct measurements of stratospheric aerosol are sparse, yet it plays an important role in Earth’s climate by scattering incoming solar radiation. The B2SAP network addresses this gap by regularly launching balloons carrying Portable Optical Particle Spectrometers (POPS) from 8 latitudinally diverse sites. The dataset provides vertical profiles of aerosol abundance and size distributions from the ground to 28 km, helping characterize global stratospheric aerosol abundance and variability.
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Short summary
Short summary
Near-surface ozone over the tropical Pacific is among the lowest on Earth. This study provides rare observations from this key region. Using sunlight measurements with an infrared spectrometer in Palau, we found that ozone rises in the morning and falls after noon. This daily rhythm and very low levels show how clean ocean air and weak thunderstorms shape atmospheric chemistry and affect Earth's climate.
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Ozone profile trends from SHADOZ sondes and IAGOS aircraft show that ozone in the tropical free troposphere (FT) is not growing fast except over equatorial SE Asia. This agrees with HEGIFTOM (Van Malderen et al., 2025), Stauffer et al. (2024) and Gaudel et al. (2024) TOAR-II papers. Other findings are as follows: (1) our trends are independent of method (QR, MLR) and (2) sample number (SN) (i.e., SHADOZ sampling is sufficient), and (3) all ground-based trends constitute the gold standard for satellite-derived trends.
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This study presents continuous ship-borne measurements of methane (CH4) concentration and isotopic composition monitored during an ice drift expedition in 2020. Using trajectory analysis, we linked atmospheric CH4 variabilities to air mass pathways transported over open water or sea-ice. The study highlights the potential of ship-borne observations to fill significant data gaps in the high Arctic.
Roeland Van Malderen, Zhou Zang, Kai-Lan Chang, Robin Björklund, Owen R. Cooper, Jane Liu, Eliane Maillard Barras, Corinne Vigouroux, Irina Petropavlovskikh, Thierry Leblanc, Valérie Thouret, Pawel Wolff, Peter Effertz, Audrey Gaudel, David W. Tarasick, Herman G. J. Smit, Anne M. Thompson, Ryan M. Stauffer, Debra E. Kollonige, Deniz Poyraz, Gérard Ancellet, Marie-Renée De Backer, Matthias M. Frey, James W. Hannigan, José L. Hernandez, Bryan J. Johnson, Nicholas Jones, Rigel Kivi, Emmanuel Mahieu, Isamu Morino, Glen McConville, Katrin Müller, Isao Murata, Justus Notholt, Ankie Piters, Maxime Prignon, Richard Querel, Vincenzo Rizi, Dan Smale, Wolfgang Steinbrecht, Kimberly Strong, and Ralf Sussmann
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Tropospheric ozone is an important greenhouse gas and an air pollutant whose distribution and time variability are mainly governed by anthropogenic emissions and dynamics. In this paper, we assess regional trends of tropospheric ozone column amounts, based on two different approaches of merging or synthesizing ground-based observations and their trends within specific regions. Our findings clearly demonstrate regional trend differences but also consistently higher pre-COVID than post-COVID trends.
Wanmin Gong, Stephen R. Beagley, Kenjiro Toyota, Henrik Skov, Jesper Heile Christensen, Alex Lupu, Diane Pendlebury, Junhua Zhang, Ulas Im, Yugo Kanaya, Alfonso Saiz-Lopez, Roberto Sommariva, Peter Effertz, John W. Halfacre, Nis Jepsen, Rigel Kivi, Theodore K. Koenig, Katrin Müller, Claus Nordstrøm, Irina Petropavlovskikh, Paul B. Shepson, William R. Simpson, Sverre Solberg, Ralf M. Staebler, David W. Tarasick, Roeland Van Malderen, and Mika Vestenius
Atmos. Chem. Phys., 25, 8355–8405, https://doi.org/10.5194/acp-25-8355-2025, https://doi.org/10.5194/acp-25-8355-2025, 2025
Short summary
Short summary
This study showed that the springtime O3 depletion plays a critical role in driving the surface O3 seasonal cycle in the central Arctic. The O3 depletion events, while occurring most notably within the lowest few hundred metres above the Arctic Ocean, can induce a 5–7 % loss in the pan-Arctic tropospheric O3 burden during springtime. The study also found enhancements in O3 and NOy (mostly peroxyacetyl nitrate) concentrations in the Arctic due to northern boreal wildfires, particularly at higher altitudes.
Roeland Van Malderen, Anne M. Thompson, Debra E. Kollonige, Ryan M. Stauffer, Herman G. J. Smit, Eliane Maillard Barras, Corinne Vigouroux, Irina Petropavlovskikh, Thierry Leblanc, Valérie Thouret, Pawel Wolff, Peter Effertz, David W. Tarasick, Deniz Poyraz, Gérard Ancellet, Marie-Renée De Backer, Stéphanie Evan, Victoria Flood, Matthias M. Frey, James W. Hannigan, José L. Hernandez, Marco Iarlori, Bryan J. Johnson, Nicholas Jones, Rigel Kivi, Emmanuel Mahieu, Glen McConville, Katrin Müller, Tomoo Nagahama, Justus Notholt, Ankie Piters, Natalia Prats, Richard Querel, Dan Smale, Wolfgang Steinbrecht, Kimberly Strong, and Ralf Sussmann
Atmos. Chem. Phys., 25, 7187–7225, https://doi.org/10.5194/acp-25-7187-2025, https://doi.org/10.5194/acp-25-7187-2025, 2025
Short summary
Short summary
Tropospheric ozone is an important greenhouse gas and is an air pollutant. The time variability of tropospheric ozone is mainly driven by anthropogenic emissions. In this paper, we study the distribution and time variability of ozone from harmonized ground-based observations from five different measurement techniques. Our findings provide clear standard references for atmospheric models and evolving tropospheric ozone satellite data for the 2000–2022 period.
Xiaoyu Sun, Katrin Müller, Mathias Palm, Christoph Ritter, Denghui Ji, Tim Balthasar Röpke, and Justus Notholt
Atmos. Chem. Phys., 25, 6881–6902, https://doi.org/10.5194/acp-25-6881-2025, https://doi.org/10.5194/acp-25-6881-2025, 2025
Short summary
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We studied how air moves from the lower atmosphere to the stratosphere over the tropical western Pacific. Using observations and air tracking, we found that, in winter, air ascends and cold temperatures freeze water out, drying it before it enters the stratosphere. In summer, air tends to sink after cloud formation. This process affects water vapor amounts in the stratosphere, influencing the greenhouse effect and climate.
Falco Monsees, Alexei Rozanov, John P. Burrows, Mark Weber, Annette Rinke, Ralf Jaiser, and Peter von der Gathen
Atmos. Chem. Phys., 24, 9085–9099, https://doi.org/10.5194/acp-24-9085-2024, https://doi.org/10.5194/acp-24-9085-2024, 2024
Short summary
Short summary
Cyclones strongly influence weather predictability but still cannot be fully characterised in the Arctic because of the sparse coverage of meteorological measurements. A potential approach to compensate for this is the use of satellite measurements of ozone, because cyclones impact the tropopause and therefore also ozone. In this study we used this connection to investigate the correlation between ozone and the tropopause in the Arctic and to identify cyclones with satellite ozone observations.
Katrin Müller, Jordis S. Tradowsky, Peter von der Gathen, Christoph Ritter, Sharon Patris, Justus Notholt, and Markus Rex
Atmos. Chem. Phys., 24, 2169–2193, https://doi.org/10.5194/acp-24-2169-2024, https://doi.org/10.5194/acp-24-2169-2024, 2024
Short summary
Short summary
The Palau Atmospheric Observatory is introduced as an ideal site to detect changes in atmospheric composition and dynamics above the remote tropical western Pacific. We focus on the ozone sounding program from 2016–2021, including El Niño 2016. The year-round high convective activity is reflected in dominant low tropospheric ozone and high relative humidity. Their seasonal distributions are unique compared to other tropical sites and are modulated by the Intertropical Convergence Zone.
Bianca Zilker, Andreas Richter, Anne-Marlene Blechschmidt, Peter von der Gathen, Ilias Bougoudis, Sora Seo, Tim Bösch, and John Philip Burrows
Atmos. Chem. Phys., 23, 9787–9814, https://doi.org/10.5194/acp-23-9787-2023, https://doi.org/10.5194/acp-23-9787-2023, 2023
Short summary
Short summary
During Arctic spring, near-surface ozone is depleted by bromine released from salty sea ice and/or snow-covered areas under certain meteorological conditions. To study this ozone depletion and the prevailing meteorological conditions, two ozone data sets from Ny-Ålesund, Svalbard, have been evaluated. We found that during ozone depletion events lower pressure over the Barents Sea and higher pressure in the Icelandic Low area led to a transport of cold polar air from the north to Ny-Ålesund.
Xiaoyu Sun, Mathias Palm, Katrin Müller, Jonas Hachmeister, and Justus Notholt
Atmos. Chem. Phys., 23, 7075–7090, https://doi.org/10.5194/acp-23-7075-2023, https://doi.org/10.5194/acp-23-7075-2023, 2023
Short summary
Short summary
The tropical western Pacific (TWP) is an active interhemispheric transport region contributing significantly to the global climate. A method to determine the chemical equator was developed by model simulations of a virtual passive tracer to analyze transport in the tropics, with a focus on the TWP region. We compare the chemical equator with tropical rain belts and wind fields and obtain a vertical pattern of interhemispheric transport processes which shows tilt structure in certain seasons.
Klaus Dethloff, Wieslaw Maslowski, Stefan Hendricks, Younjoo J. Lee, Helge F. Goessling, Thomas Krumpen, Christian Haas, Dörthe Handorf, Robert Ricker, Vladimir Bessonov, John J. Cassano, Jaclyn Clement Kinney, Robert Osinski, Markus Rex, Annette Rinke, Julia Sokolova, and Anja Sommerfeld
The Cryosphere, 16, 981–1005, https://doi.org/10.5194/tc-16-981-2022, https://doi.org/10.5194/tc-16-981-2022, 2022
Short summary
Short summary
Sea ice thickness anomalies during the MOSAiC (Multidisciplinary drifting Observatory for the Study of Arctic Climate) winter in January, February and March 2020 were simulated with the coupled Regional Arctic climate System Model (RASM) and compared with CryoSat-2/SMOS satellite data. Hindcast and ensemble simulations indicate that the sea ice anomalies are driven by nonlinear interactions between ice growth processes and wind-driven sea-ice transports, with dynamics playing a dominant role.
Cited articles
Anderson, D. C., Nicely, J. M., Salawitch, R. J., Canty, T. P., Dickerson, R. R., Hanisco, T. F., Wolfe, G. M., Apel, E. C., Atlas, E., Bannan, T., Bauguitte, S., Blake, N. J., Bresch, J. F., Campos, T. L., Carpenter, L. J., Cohen, M. D., Evans, M., Fernandez, R. P., Kahn, B. H., Kinnison, D. E., Hall, S. R., Harris, N. R., Hornbrook, R. S., Lamarque, J.-F., Le Breton, M., Lee, J. D., Percival, C., Pfister, L., Pierce, R. B., Riemer, D. D., Saiz-Lopez, A., Stunder, B. J., Thompson, A. M., Ullmann, K., Vaughan, A., and Weinheimer, A. J.: A Pervasive Role for Biomass Burning in Tropical High Ozone/Low Water Structures, Nat. Commun., 7, 10267, https://doi.org/10.1038/ncomms10267, 2016. a, b, c, d, e, f, g, h, i, j, k, l, m, n, o, p
Bozem, H., Butler, T. M., Lawrence, M. G., Harder, H., Martinez, M., Kubistin, D., Lelieveld, J., and Fischer, H.: Chemical processes related to net ozone tendencies in the free troposphere, Atmos. Chem. Phys., 17, 10565–10582, https://doi.org/10.5194/acp-17-10565-2017, 2017. a
Browell, E. V., Fenn, M. A., Butler, C. F., Grant, W. B., Ismail, S., Ferrare, R. A., Kooi, S. A., Brackett, V. G., Clayton, M. B., Avery, M. A., Barrick, J. D. W., Fuelberg, H. E., Maloney, J. C., Newell, R. E., Zhu, Y., Mahoney, M. J., Anderson, B. E., Blake, D. R., Brune, W. H., Heikes, B. G., Sachse, G. W., Singh, H. B., and Talbot, R. W.: Large-scale Air Mass Characteristics Observed over the Remote Tropical Pacific Ocean during March–April 1999: Results from PEM-Tropics B Field Experiment, J. Geophys. Res.-Atmos., 106, 32481–32501, https://doi.org/10.1029/2001JD900001, 2001. a, b
Cau, P., Methven, J., and Hoskins, B.: Origins of Dry Air in the Tropics and Subtropics, J. Climate, 20, 2745–2759, https://doi.org/10.1175/JCLI4176.1, 2007. a, b
Cecil, D. J., Buechler, D. E., and Blakeslee, R. J.: Gridded Lightning Climatology from TRMM-LIS and OTD: Dataset Description, Atmos. Res., 135–136, 404–414, https://doi.org/10.1016/j.atmosres.2012.06.028, 2014. a
Christian, H. J.: Global Frequency and Distribution of Lightning as Observed from Space by the Optical Transient Detector, J. Geophys. Res., 108, 4005, https://doi.org/10.1029/2002JD002347, 2003. a
Crawford, J. H., Davis, D. D., Chen, G., Bradshaw, J., Sandholm, S., Kondo, Y., Merrill, J., Liu, S., Browell, E., Gregory, G., Anderson, B., Sachse, G., Barrick, J., Blake, D., Talbot, R., and Pueschel, R.: Implications of Large Scale Shifts in Tropospheric NOx Levels in the Remote Tropical Pacific, J. Geophys. Res.-Atmos., 102, 28447–28468, https://doi.org/10.1029/97JD00011, 1997. a, b
Dessler, A. E. and Minschwaner, K.: An Analysis of the Regulation of Tropical Tropospheric Water Vapor, J. Geophys. Res.-Atmos., 112, D10120, https://doi.org/10.1029/2006JD007683, 2007. a, b
Diallo, M., Riese, M., Birner, T., Konopka, P., Müller, R., Hegglin, M. I., Santee, M. L., Baldwin, M., Legras, B., and Ploeger, F.: Response of stratospheric water vapor and ozone to the unusual timing of El Niño and the QBO disruption in 2015–2016, Atmos. Chem. Phys., 18, 13055–13073, https://doi.org/10.5194/acp-18-13055-2018, 2018. a
Dima, I. M., Wallace, J., M., and Kraucunas, I.: Tropical Zonal Momentum Balance in the NCEP Reanalyses, J. Atmos. Sci., 62, 2499–2513, https://doi.org/10.1175/JAS3486.1, 2005. a, b, c
ECMWF: ERA5 data, ECMWF MARS archive [data set], https://apps.ecmwf.int/data-catalogues/era5/?stream=moda&levtype=sfc&expver=1&type=an&class=ea, last access: 22 August 2022. a
Folkins, I. and Martin, R. V.: The Vertical Structure of Tropical Convection and Its Impact on the Budgets of Water Vapor and Ozone, J. Atmos. Sci., 62, 1560–1573, https://doi.org/10.1175/JAS3407.1, 2005. a
Fueglistaler, S., Wernli, H., and Peter, T.: Tropical Troposphere-to-Stratosphere Transport Inferred from Trajectory Calculations, J. Geophys. Res.-Atmos., 109, D03108, https://doi.org/10.1029/2003JD004069, 2004. a
Gettelman, A. and Forster, P. d. F.: A Climatology of the Tropical Tropopause Layer, J. Meteorol. Soc. Jpn., 80, 911–924, https://doi.org/10.2151/jmsj.80.911, 2002. a, b
Gettelman, A., Lauritzen, P. H., Park, M., and Kay, J. E.: Processes Regulating Short-Lived Species in the Tropical Tropopause Layer, J. Geophys. Res., 114, D13303, https://doi.org/10.1029/2009JD011785, 2009. a
Gill, A. E.: Some simple solutions for heat-induced tropical circulation, Q. J. Roy. Meteor. Soc., 106, 447–462, 1980. a
Harris, N. R. P., Carpenter, L. J., Lee, J. D., Vaughan, G., Filus, M. T., Jones, R. L., OuYang, B., Pyle, J. A., Robinson, A. D., Andrews, S. J., Lewis, A. C., Minaeian, J., Vaughan, A., Dorsey, J. R., Gallagher, M. W., Le Breton, M., Newton, R., Percival, C. J., Ricketts, H. M. A., Bauguitte, S. J.-B., Nott, G. J., Wellpott, A., Ashfold, M. J., Flemming, J., Butler, R., Palmer, P. I., Kaye, P. H., Stopford, C., Chemel, C., Boesch, H., Humpage, N., Vick, A., MacKenzie, A. R., Hyde, R., Angelov, P., Meneguz, E., and Manning, A. J.: Coordinated Airborne Studies in the Tropics (CAST), B. Am. Meteorol. Soc., 98, 145–162, https://doi.org/10.1175/BAMS-D-14-00290.1, 2017. a
Hersbach, H., Bell, B., Berrisford, P., Hirahara, S., Horányi, A., Muñoz-Sabater, J., Nicolas, J., Peubey, C., Radu, R., Schepers, D., Simmons, A., Soci, C., Abdalla, S., Abellan, X., Balsamo, G., Bechtold, P., Biavati, G., Bidlot, J., Bonavita, M., Chiara, G., Dahlgren, P., Dee, D., Diamantakis, M., Dragani, R., Flemming, J., Forbes, R., Fuentes, M., Geer, A., Haimberger, L., Healy, S., Hogan, R. J., Hólm, E., Janisková, M., Keeley, S., Laloyaux, P., Lopez, P., Lupu, C., Radnoti, G., Rosnay, P., Rozum, I., Vamborg, F., Villaume, S., and Thépaut, J.-N.: The ERA5 Global Reanalysis, Q. J. Roy. Meteor. Soc., 146, 1999–2049, https://doi.org/10.1002/qj.3803, 2020. a, b
Huang, B., L'Heureux, M., Hu, Z.-Z., and Zhang, H.-M.: Ranking the Strongest ENSO Events While Incorporating SST Uncertainty, Geophys. Res. Lett., 43, 9165–9172, 2016. a
Kley, D., Smit, H. G. J., Vömel, H., Grassl, H., Ramanathan, V., Crutzen, P. J., Williams, S., Meywerk, J., and Oltmans, S. J.: Tropospheric Water-Vapour and Ozone Cross-Sections in a Zonal Plane over the Central Equatorial Pacific Ocean, Q. J. Roy. Meteor. Soc., 123, 2009–2040, https://doi.org/10.1002/qj.49712354312, 1997. a, b, c
Komhyr, W. D.: Electrical Concentration Cells for Gas Analysis, Ann. Geophys., 25, 203–210, 1969. a
Krüger, K. and Quack, B.: Introduction to special issue: the TransBrom Sonne expedition in the tropical West Pacific, Atmos. Chem. Phys., 13, 9439–9446, https://doi.org/10.5194/acp-13-9439-2013, 2013. a
Krüger, K., Tegtmeier, S., and Rex, M.: Long-term climatology of air mass transport through the Tropical Tropopause Layer (TTL) during NH winter, Atmos. Chem. Phys., 8, 813–823, https://doi.org/10.5194/acp-8-813-2008, 2008. a
Kunz, A., Konopka, P., Müller, R., and Pan, L. L.: Dynamical Tropopause Based on Isentropic Potential Vorticity Gradients, J. Geophys. Res., 116, D01110, https://doi.org/10.1029/2010JD014343, 2011. a
Levy, H.: Normal Atmosphere: Large Radical and Formaldehyde Concentrations Predicted, Science, 173, 141–143, https://doi.org/10.1126/science.173.3992.141, 1971. a, b
Liu, S. C., McFarland, M., Kley, D., Zafiriou, O., and Huebert, B.: Tropospheric NOx and O3 Budgets in the Equatorial Pacific, J. Geophys. Res., 88, 1360, https://doi.org/10.1029/JC088iC02p01360, 1983. a, b
Mapes, B. E.: Water's Two Height Scales: The Moist Adiabat and the Radiative Troposphere, Q. J. Roy. Meteor. Soc., 127, 2353–2366, https://doi.org/10.1002/qj.49712757708, 2001. a
Mapes, B. E. and Zuidema, P.: Radiative-Dynamical Consequences of Dry Tongues in the Tropical Troposphere, J. Atmos. Sci., 53, 620–638, https://doi.org/10.1175/1520-0469(1996)053<0620:RDCODT>2.0.CO;2, 1996. a
Matsuno, T.: Quasi-geostrophic motions in the equatorial area, J. Meteorol. Soc. Jpn. Ser. II, 44, 25–43, 1966. a
Müller, K. and Wohltmann, I.: ATLAS Backward Trajectory Dataset for the Palau Atmospheric Observatory Balloon-borne ozonesonde record 2016–2019, Zenodo [data set], https://doi.org/10.5281/zenodo.8038600, 2023. a
Müller, K., Graeser, J., Patris, S., Beninga, I., Ruhe, W., Ucharm, G., and Tradowsky, J.: Ozone sonde and radio sonde data record Palau Atmospheric Observatory 2016–2021 (V1.0), Zenodo [data set], https://doi.org/10.5281/zenodo.6920648, 2022. a
Müller, K., Tradowsky, J. S., von der Gathen, P., Ritter, C., Patris, S., Notholt, J., and Rex, M.: Measurement report: The Palau Atmospheric Observatory and its ozonesonde record – continuous monitoring of tropospheric composition and dynamics in the tropical western Pacific, Atmos. Chem. Phys., 24, 2169–2193, https://doi.org/10.5194/acp-24-2169-2024, 2024. a, b, c, d, e, f, g, h, i, j, k, l, m, n, o, p, q, r, s, t, u, v
Newell, R. E. and Gould-Stewart, S.: A Stratospheric Fountain?, J. Atmos. Sci., 38, 2789–2796, 1981. a
Newell, R. E., Zhu, Y., Browell, E. V., Ismail, S., Read, W. G., Waters, J. W., Kelly, K. K., and Liu, S. C.: Upper Tropospheric Water Vapor and Cirrus: Comparison of DC-8 Observations, Preliminary UARS Microwave Limb Sounder Measurements and Meteorological Analyses, J. Geophys. Res.-Atmos., 101, 1931–1941, 1996. a
Newell, R. E., Thouret, V., Cho, J. Y. N., Stoller, P., Marenco, A., and Smit, H. G.: Ubiquity of Quasi-Horizontal Layers in the Troposphere, Nature, 398, 316–319, https://doi.org/10.1038/18642, 1999. a
Newton, R., Vaughan, G., Ricketts, H. M. A., Pan, L. L., Weinheimer, A. J., and Chemel, C.: Ozonesonde profiles from the West Pacific Warm Pool: measurements and validation, Atmos. Chem. Phys., 16, 619–634, https://doi.org/10.5194/acp-16-619-2016, 2016. a
Nicely, J. M., Anderson, D. C., Canty, T. P., Salawitch, R. J., Wolfe, G. M., Apel, E. C., Arnold, S. R., Atlas, E. L., Blake, N. J., Bresch, J. F., Campos, T. L., Dickerson, R. R., Duncan, B., Emmons, L. K., Evans, M. J., Fernandez, R. P., Flemming, J., Hall, S. R., Hanisco, T. F., Honomichl, S. B., Hornbrook, R. S., Huijnen, V., Kaser, L., Kinnison, D. E., Lamarque, J.-F., Mao, J., Monks, S. A., Montzka, D. D., Pan, L. L., Riemer, D. D., Saiz-Lopez, A., Steenrod, S. D., Stell, M. H., Tilmes, S., Turquety, S., Ullmann, K., and Weinheimer, A. J.: An Observationally Constrained Evaluation of the Oxidative Capacity in the Tropical Western Pacific Troposphere: Observationally Constrained OH in TWP, J. Geophys. Res.-Atmos., 121, 7461–7488, https://doi.org/10.1002/2016JD025067, 2016. a, b, c, d
Ogino, S.-Y., Fujiwara, M., Shiotani, M., Hasebe, F., Matsumoto, J., Hoang, T. H., and Nguyen, T. T.: Ozone Variations over the Northern Subtropical Region Revealed by Ozonesonde Observations in Hanoi, J. Geophys. Res.-Atmos., 118, 3245–3257, https://doi.org/10.1002/jgrd.50348, 2013. a
Ogino, S.-Y., Miyazaki, K., Fujiwara, M., Nodzu, M. I., Shiotani, M., Hasebe, F., Matsumoto, J., Witte, J., Thompson, A. M., Nguyen-Thi, H. A., and Nguyen, T. V.: Cause of a Lower-Tropospheric High-Ozone Layer in Spring Over Hanoi, J. Geophys. Res.-Atmos., 127, e2021JD035727, https://doi.org/10.1029/2021JD035727, 2022. a
Oltmans, S. J., Johnson, B. J., Harris, J. M., Vömel, H., Thompson, A. M., Koshy, K., Simon, P., Bendura, R. J., Logan, J. A., Hasebe, F., Shiotani, M., Kirchhoff, V. W. J. H., Maata, M., Sami, G., Samad, A., Tabuadravu, J., Enriquez, H., Agama, M., Cornejo, J., and Paredes, F.: Ozone in the Pacific Tropical Troposphere from Ozonesonde Observations, J. Geophys. Res.-Atmos., 106, 32503–32525, https://doi.org/10.1029/2000JD900834, 2001. a
Pan, L. L., Paulik, L. C., Honomichl, S. B., Munchak, L. A., Bian, J., Selkirk, H. B., and Vömel, H.: Identification of the Tropical Tropopause Transition Layer Using the Ozone-Water Vapor Relationship, J. Geophys. Res.-Atmos., 119, 3586–3599, https://doi.org/10.1002/2013JD020558, 2014. a
Pan, L. L., Honomichl, S. B., Randel, W. J., Apel, E. C., Atlas, E. L., Beaton, S. P., Bresch, J. F., Hornbrook, R., Kinnison, D. E., Lamarque, J.-F., Saiz-Lopez, A., Salawitch, R. J., and Weinheimer, A. J.: Bimodal Distribution of Free Tropospheric Ozone over the Tropical Western Pacific Revealed by Airborne Observations, Geophys. Res. Lett., 42, 7844–7851, https://doi.org/10.1002/2015GL065562, 2015. a, b, c, d, e, f, g, h, i, j
Pan, L. L., Atlas, E. L., Salawitch, R. J., Honomichl, S. B., Bresch, J. F., Randel, W. J., Apel, E. C., Hornbrook, R. S., Weinheimer, A. J., Anderson, D. C., Andrews, S. J., Baidar, S., Beaton, S. P., Campos, T. L., Carpenter, L. J., Chen, D., Dix, B., Donets, V., Hall, S. R., Hanisco, T. F., Homeyer, C. R., Huey, L. G., Jensen, J. B., Kaser, L., Kinnison, D. E., Koenig, T. K., Lamarque, J.-F., Liu, C., Luo, J., Luo, Z. J., Montzka, D. D., Nicely, J. M., Pierce, R. B., Riemer, D. D., Robinson, T., Romashkin, P., Saiz-Lopez, A., Schauffler, S., Shieh, O., Stell, M. H., Ullmann, K., Vaughan, G., Volkamer, R., and Wolfe, G.: The Convective Transport of Active Species in the Tropics (CONTRAST) Experiment, B. Am. Meteorol. Soc., 98, 106–128, https://doi.org/10.1175/BAMS-D-14-00272.1, 2017. a, b, c
Paulik, L. C. and Birner, T.: Quantifying the deep convective temperature signal within the tropical tropopause layer (TTL), Atmos. Chem. Phys., 12, 12183–12195, https://doi.org/10.5194/acp-12-12183-2012, 2012. a
Ploeger, F., Fueglistaler, S., Grooß, J.-U., Günther, G., Konopka, P., Liu, Y. S., Müller, R., Ravegnani, F., Schiller, C., Ulanovski, A., and Riese, M.: Insight from ozone and water vapour on transport in the tropical tropopause layer (TTL), Atmos. Chem. Phys., 11, 407–419, https://doi.org/10.5194/acp-11-407-2011, 2011. a
Randel, W. J., Park, M., Wu, F., and Livesey, N.: A Large Annual Cycle in Ozone above the Tropical Tropopause Linked to the Brewer–Dobson Circulation, J. Atmos. Sci., 64, 4479–4488, https://doi.org/10.1175/2007JAS2409.1, 2007. a
Randel, W. J., Rivoire, L., Pan, L. L., and Honomichl, S. B.: Dry Layers in the Tropical Troposphere Observed during CONTRAST and Global Behavior from GFS Analyses: Dry Layers in the Tropical Troposphere, J. Geophys. Res.-Atmos., 121, 14142–14158, https://doi.org/10.1002/2016JD025841, 2016. a, b, c, d, e, f
Rex, M., Wohltmann, I., Ridder, T., Lehmann, R., Rosenlof, K., Wennberg, P., Weisenstein, D., Notholt, J., Krüger, K., Mohr, V., and Tegtmeier, S.: A tropical West Pacific OH minimum and implications for stratospheric composition, Atmos. Chem. Phys., 14, 4827–4841, https://doi.org/10.5194/acp-14-4827-2014, 2014. a, b, c, d, e
Ruzmaikin, A., Aumann, H. H., and Manning, E. M.: Relative Humidity in the Troposphere with AIRS, J. Atmos. Sci., 71, 2516–2533, https://doi.org/10.1175/JAS-D-13-0363.1, 2014. a
Schoeberl, M. R., Selkirk, H. B., Vömel, H., and Douglass, A. R.: Sources of Seasonal Variability in Tropical Upper Troposphere and Lower Stratosphere Water Vapor and Ozone: Inferences from the Ticosonde Data Set at Costa Rica, J. Geophys. Res.-Atmos., 120, 9684–9701, https://doi.org/10.1002/2015JD023299, 2015. a, b, c
Sherwood, S. C., Kursinski, E. R., and Read, W. G.: A Distribution Law for Free-Tropospheric Relative Humidity, J. Climate, 19, 6267–6277, https://doi.org/10.1175/JCLI3978.1, 2006. a
Sherwood, S. C., Roca, R., Weckwerth, T. M., and Andronova, N. G.: Tropospheric Water Vapor, Convection, and Climate, Rev. Geophys., 48, RG2001, https://doi.org/10.1029/2009RG000301, 2010. a, b
Smit, H. G. J., Thompson, A. M., and the ASOPOS 2.0 Panel: Ozonesonde Measurement Principles and Best Operational Practices, WMO Global Atmosphere Watch Report Series, No. 268, World Meteorological Organization, Geneva, https://library.wmo.int/idurl/4/57720 (last access: 8 January 2024), 2021. a
Solomon, S., Thompson, D. W. J., Portmann, R. W., Oltmans, S. J., and Thompson, A. M.: On the Distribution and Variability of Ozone in the Tropical Upper Troposphere: Implications for Tropical Deep Convection and Chemical-Dynamical Coupling, Geophys. Res. Lett., 32, L23813, https://doi.org/10.1029/2005GL024323, 2005. a, b
Stauffer, R. M., Thompson, A. M., and Witte, J. C.: Characterizing Global Ozonesonde Profile Variability From Surface to the UT/LS With a Clustering Technique and MERRA-2 Reanalysis, J. Geophys. Res.-Atmos., 123, 6213–6229, https://doi.org/10.1029/2018JD028465, 2018. a, b
Stoller, P., Cho, J. Y. N., Newell, R. E., Thouret, V., Zhu, Y., Carroll, M. A., Albercook, G. M., Anderson, B. E., Barrick, J. D. W., Browell, E. V., Gregory, G. L., Sachse, G. W., Vay, S., Bradshaw, J. D., and Sandholm, S.: Measurements of Atmospheric Layers from the NASA DC-8 and P-3B Aircraft during PEM-Tropics A, J. Geophys. Res.-Atmos., 104, 5745–5764, https://doi.org/10.1029/98JD02717, 1999. a, b, c, d, e, f, g, h, i
Sun, X., Palm, M., Müller, K., Hachmeister, J., and Notholt, J.: Determination of the chemical equator from GEOS-Chem model simulation: a focus on the tropical western Pacific region, Atmos. Chem. Phys., 23, 7075–7090, https://doi.org/10.5194/acp-23-7075-2023, 2023. a, b
Takashima, H., Shiotani, M., Fujiwara, M., Nishi, N., and Hasebe, F.: Ozonesonde Observations at Christmas Island (2° N, 157° W) in the Equatorial Central Pacific, J. Geophys. Res., 113, D10112, https://doi.org/10.1029/2007JD009374, 2008. a
Thompson, A. M., Tao, W.-K., Pickering, K. E., Scala, J. R., and Simpson, J.: Tropical Deep Convection and Ozone Formation, B. Am. Meteorol. Soc., 78, 1043–1054, https://doi.org/10.1175/1520-0477(1997)078<1043:TDCAOF>2.0.CO;2, 1997. a
Thompson, A. M., Witte, J. C., McPeters, R. D., Oltmans, S. J., Schmidlin, F. J., Logan, J. A., Fujiwara, M., Kirchhoff, V. W. J. H., Posny, F., Coetzee, G. J. R., Hoegger, B., Kawakami, S., Toshihiro, O., Johnson, B. J., Vömel, H., and Labow, G. J.: Southern Hemisphere Additional Ozonesondes (SHADOZ) 1998–2000 Tropical Ozone Climatology 1. Comparison with Total Ozone Mapping Spectrometer (TOMS) and Ground-Based Measurements, J. Geophys. Res., 108, 8238, https://doi.org/10.1029/2001JD000967, 2003a. a, b
Thompson, A. M., Witte, J. C., Oltmans, S. J., Schmidlin, F. J., Logan, J. A., Fujiwara, M., Kirchhoff, V. W. J. H., Posny, F., Coetzee, G. J. R., Hoegger, B., Kawakami, S., Ogawa, T., Fortuin, J. P. F., and Kelder, H. M.: Southern Hemisphere Additional Ozonesondes (SHADOZ) 1998–2000 Tropical Ozone Climatology 2. Tropospheric Variability and the Zonal Wave-One, J. Geophys. Res., 108, 8241, https://doi.org/10.1029/2002JD002241, 2003b. a, b, c, d
Thompson, A. M., Miller, S. K., Tilmes, S., Kollonige, D. W., Witte, J. C., Oltmans, S. J., Johnson, B. J., Fujiwara, M., Schmidlin, F. J., Coetzee, G. J. R., Komala, N., Maata, M., bt Mohamad, M., Nguyo, J., Mutai, C., Ogino, S.-Y., Da Silva, F. R., Leme, N. M. P., Posny, F., Scheele, R., Selkirk, H. B., Shiotani, M., Stübi, R., Levrat, G., Calpini, B., Thouret, V., Tsuruta, H., Canossa, J. V., Vömel, H., Yonemura, S., Diaz, J. A., Tan Thanh, N. T., and Thuy Ha, H. T.: Southern Hemisphere Additional Ozonesondes (SHADOZ) Ozone Climatology (2005-2009): Tropospheric and Tropical Tropopause Layer (TTL) Profiles with Comparisons to OMI-based Ozone Products, J. Geophys. Res.-Atmos., 117, D23301, https://doi.org/10.1029/2011JD016911, 2012. a
Thompson, A. M., Witte, J. C., Sterling, C., Jordan, A., Johnson, B. J., Oltmans, S. J., Fujiwara, M., Vömel, H., Allaart, M., Piters, A., Coetzee, G. J. R., Posny, F., Corrales, E., Diaz, J. A., Félix, C., Komala, N., Lai, N., Ahn Nguyen, H. T., Maata, M., Mani, F., Zainal, Z., Ogino, S.-y., Paredes, F., Penha, T. L. B., Silva, F. R., Sallons-Mitro, S., Selkirk, H. B., Schmidlin, F. J., Stübi, R., and Thiongo, K.: First Reprocessing of Southern Hemisphere Additional Ozonesondes (SHADOZ) Ozone Profiles (1998–2016): 2. Comparisons With Satellites and Ground-Based Instruments, J. Geophys. Res.-Atmos., 122, 13000–13025, https://doi.org/10.1002/2017JD027406, 2017. a
Thompson, A. M., Smit, H. G. J., Witte, J. C., Stauffer, R. M., Johnson, B. J., Morris, G., von der Gathen, P., Van Malderen, R., Davies, J., Piters, A., Allaart, M., Posny, F., Kivi, R., Cullis, P., Hoang Anh, N. T., Corrales, E., Machinini, T., da Silva, F. R., Paiman, G., Thiong'o, K., Zainal, Z., Brothers, G. B., Wolff, K. R., Nakano, T., Stübi, R., Romanens, G., Coetzee, G. J. R., Diaz, J. A., Mitro, S., Mohamad, M., and Ogino, S.-Y.: Ozonesonde Quality Assurance: The JOSIE–SHADOZ (2017) Experience, B. Am. Meteorol. Soc., 100, 155–171, https://doi.org/10.1175/BAMS-D-17-0311.1, 2019. a
Thompson, A. M., Stauffer, R. M., Wargan, K., Witte, J. C., Kollonige, D. E., and Ziemke, J. R.: Regional and Seasonal Trends in Tropical Ozone From SHADOZ Profiles: Reference for Models and Satellite Products, J. Geophys. Res.-Atmos., 126, e2021JD034691, https://doi.org/10.1029/2021JD034691, 2021. a
Thouret, V., Cho, J. Y. N., Newell, R. E., Marenco, A., and Smit, H. G. J.: General Characteristics of Tropospheric Trace Constituent Layers Observed in the MOZAIC Program, J. Geophys. Res.-Atmos., 105, 17379–17392, https://doi.org/10.1029/2000JD900238, 2000. a, b, c
Van Tuyl, A. H.: Advective influences on forced tropical motions, J. Atmos. Sci., 43, 141–161, 1986. a
Waugh, D. W. and Polvani, L. M.: Climatology of Intrusions into the Tropical Upper Troposphere, Geophys. Res. Lett., 27, 3857–3860, https://doi.org/10.1029/2000GL012250, 2000. a
Wohltmann, I. and Rex, M.: The Lagrangian chemistry and transport model ATLAS: validation of advective transport and mixing, Geosci. Model Dev., 2, 153–173, https://doi.org/10.5194/gmd-2-153-2009, 2009. a
Wohltmann, I., Lehmann, R., and Rex, M.: The Lagrangian chemistry and transport model ATLAS: simulation and validation of stratospheric chemistry and ozone loss in the winter 1999/2000, Geosci. Model Dev., 3, 585–601, https://doi.org/10.5194/gmd-3-585-2010, 2010. a
Yadav, I. C., Linthoingambi Devi, N., Li, J., Syed, J. H., Zhang, G., and Watanabe, H.: Biomass burning in Indo-China peninsula and its impacts on regional air quality and global climate change – a review, Environ. Pollut., 227, 414–427, https://doi.org/10.1016/j.envpol.2017.04.085, 2017. a
Yoneyama, K. and Parsons, D. B.: A Proposed Mechanism for the Intrusion of Dry Air into the Tropical Western Pacific Region, J. Atmos. Sci., 56, 1524–1546, https://doi.org/10.1175/1520-0469(1999)056<1524:APMFTI>2.0.CO;2, 1999. a
Zhang, C., Mapes, B. E., and Soden, B. J.: Bimodality in tropical water vapour, Q. J. Roy. Meteor. Soc., 129, 2847–2866, https://doi.org/10.1256/qj.02.166, 2003. a, b
Short summary
The transport history of tropospheric air masses above the tropical western Pacific is studied by local ozone and relative humidity profile measurements from Palau. A prominent anti-correlation between both tracers separates air masses of different origin and genesis. Back trajectories confirm a local convective origin of the year-round humid ozone-poor background. Anomalously dry ozone-rich air is generated in tropical Asia by pollution and dehydrated during transport via radiative cooling.
The transport history of tropospheric air masses above the tropical western Pacific is studied...
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