Preprints
https://doi.org/10.5194/egusphere-2026-3649
© Author(s) 2026. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
https://doi.org/10.5194/egusphere-2026-3649
© Author(s) 2026. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
09 Jul 2026
| 09 Jul 2026
Status: this preprint is open for discussion and under review for Atmospheric Chemistry and Physics (ACP).
Global atmospheric aerosol distributions and composition from the Earth's surface to the stratosphere
Abstract. Atmospheric aerosols play a crucial role in Earth’s climate system, yet their spatio-temporal distribution, particularly in the free troposphere (FT) and upper troposphere–lower stratosphere (UTLS), remains poorly constrained, a major source of uncertainty in estimates of aerosol radiative forcing. To address this, we perform ECHAM/MESSy Atmospheric Chemistry (EMAC) model simulations with a newly developed setup, bridging the tropospheric and stratospheric regimes. Model output is evaluated against a comprehensive suite of observations of aerosol mass, number concentrations, and optical properties, showing good agreement across vertical layers and most geographical regions. The evaluated simulations provide a unified description of global distributions of key aerosol species, their composition, and number concentrations from the Earth's surface to the stratosphere. Simulated aerosol mass exhibits a global minimum between 400 and 200 hPa, marking the transition between FT and UTLS, with particle numbers peaking at similar altitudes or slightly higher in the tropics. Primary particles contribute less than 3.5 % to aerosol mass in the stratospheric overworld up to 10 hPa, substantially less than suggested by previous modelling studies and in closer agreement with recent observations. Stratospheric aerosol mass is dominated by sulfate, with a notable contribution (~15 %) from secondary organic aerosol throughout the global lower stratosphere. This work provides new constraints on aerosol distributions in the FT and UTLS, which remain underrepresented in global modelling studies, and enables future research on aerosol-climate interactions in this critical atmospheric regime.
How to cite. Kohl, M., Brühl, C., Tost, H., Xenofontos, C., Christoudias, T., Gromov, S., Appel, O., Borrmann, S., Bourassa, A., Campunzano-Jost, P., Cheng, Y., Eppers, O., Froyd, K. D., Holanda, B. A., Jimenez, J. L., Jöckel, P., Joppe, P., Kaiser, K., Katich, J. M., Klingmüller, K., Köllner, F., Kupc, A., Martin, A., Pöhlker, C., Pöhlker, M. L., Pöschl, U., Rieger, L., Ruhl, S., Schill, G. P., Schneider, J., Schulz, C., Schwarz, J. P., Tsimpidi, A. P., Vella, R., Williamson, C. J., Yang, Y., Zawada, D., Lelieveld, J., and Pozzer, A.: Global atmospheric aerosol distributions and composition from the Earth's surface to the stratosphere, EGUsphere [preprint], https://doi.org/10.5194/egusphere-2026-3649, 2026.
Competing interests: At least one of the (co-)authors is a member of the editorial board of Atmospheric Chemistry and Physics.
Publisher's note: Copernicus Publications remains neutral with regard to jurisdictional claims made in the text, published maps, institutional affiliations, or any other geographical representation in this paper. While Copernicus Publications makes every effort to include appropriate place names, the final responsibility lies with the authors. Views expressed in the text are those of the authors and do not necessarily reflect the views of the publisher.Download & links
- Preprint
(7346 KB) - Metadata XML
-
Supplement
(7574 KB) - BibTeX
- EndNote
Status: open (until 27 Aug 2026)
Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor
| : Report abuse
- RC1: 'Comment on egusphere-2026-3649', Anonymous Referee #1, 30 Jul 2026 reply
Viewed
Total article views: 481 (including HTML, PDF, and XML)
Cumulative views and downloads
(calculated since 09 Jul 2026)
| HTML | XML | Total | Supplement | BibTeX | EndNote | |
|---|---|---|---|---|---|---|
| 305 | 148 | 28 | 481 | 44 | 29 | 33 |
- HTML: 305
- PDF: 148
- XML: 28
- Total: 481
- Supplement: 44
- BibTeX: 29
- EndNote: 33
Viewed (geographical distribution)
Total article views: 288 (including HTML, PDF, and XML)
Thereof 288 with geography defined
and 0 with unknown origin.
| Country | # | Views | % |
|---|
| Total: | 0 |
| HTML: | 0 |
| PDF: | 0 |
| XML: | 0 |
- 1
1
Latest update: 19 Aug 2026
Atmospheric Chemistry Department, Max Planck Institute for Chemistry, Mainz, Germany
Christoph Brühl
Atmospheric Chemistry Department, Max Planck Institute for Chemistry, Mainz, Germany
Holger Tost
Institute for Physics of the Atmosphere, Johannes Gutenberg University, Mainz, Germany
Christos Xenofontos
Climate and Atmosphere Research Center, The Cyprus Institute, Nicosia, Cyprus
Theodoros Christoudias
Climate and Atmosphere Research Center, The Cyprus Institute, Nicosia, Cyprus
Sergey Gromov
Atmospheric Chemistry Department, Max Planck Institute for Chemistry, Mainz, Germany
Oliver Appel
Institute for Physics of the Atmosphere, Johannes Gutenberg University, Mainz, Germany
Aerosol Chemistry Department, Max Planck Institute for Chemistry, Mainz, Germany
Stephan Borrmann
Institute for Physics of the Atmosphere, Johannes Gutenberg University, Mainz, Germany
Aerosol Chemistry Department, Max Planck Institute for Chemistry, Mainz, Germany
Adam Bourassa
Institute of Space and Atmospheric Studies, University of Saskatchewan, Saskatchewan, Canada
Pedro Campunzano-Jost
University of Colorado Boulder, Boulder, Colorado, USA
Yafang Cheng
Aerosol Chemistry Department, Max Planck Institute for Chemistry, Mainz, Germany
Oliver Eppers
Institute for Physics of the Atmosphere, Johannes Gutenberg University, Mainz, Germany
Aerosol Chemistry Department, Max Planck Institute for Chemistry, Mainz, Germany
Karl D. Froyd
University of Colorado Boulder, Boulder, Colorado, USA
NOAA Chemical Sciences Laboratory, Boulder, Colorado, USA
Bruna A. Holanda
Multiphase Chemistry Department, Max Planck Institute for Chemistry, Mainz, Germany
now at: Hessian Agency for Nature Conservation, Environment and Geology, Wiesbaden, Germany
Jose L. Jimenez
Institute of Space and Atmospheric Studies, University of Saskatchewan, Saskatchewan, Canada
Patrick Jöckel
Deutsches Zentrum für Luft- und Raumfahrt (DLR), Institut für Physik der Atmosphäre, Oberpfaffenhofen, Germany
Philipp Joppe
Institute for Physics of the Atmosphere, Johannes Gutenberg University, Mainz, Germany
Aerosol Chemistry Department, Max Planck Institute for Chemistry, Mainz, Germany
Katharina Kaiser
Aerosol Chemistry Department, Max Planck Institute for Chemistry, Mainz, Germany
Joseph M. Katich
University of Colorado Boulder, Boulder, Colorado, USA
NOAA Chemical Sciences Laboratory, Boulder, Colorado, USA
now at: BAE Systems, Inc., Boulder, CO, USA, 80301
Klaus Klingmüller
Atmospheric Chemistry Department, Max Planck Institute for Chemistry, Mainz, Germany
Franziska Köllner
Institute for Physics of the Atmosphere, Johannes Gutenberg University, Mainz, Germany
Aerosol Chemistry Department, Max Planck Institute for Chemistry, Mainz, Germany
Agnieszka Kupc
Aerosol Physics and Environmental Physics, Faculty of Physics, University of Vienna, Vienna, Austria
Anna Martin
Atmospheric Chemistry Department, Max Planck Institute for Chemistry, Mainz, Germany
Christopher Pöhlker
Multiphase Chemistry Department, Max Planck Institute for Chemistry, Mainz, Germany
now at: Physikalisch-Technische Bundesanstalt (PTB), Braunschweig, Germany
Mira L. Pöhlker
Leibniz Institute for Tropospheric Research (TROPOS), Leipzig, Germany
Ulrich Pöschl
Multiphase Chemistry Department, Max Planck Institute for Chemistry, Mainz, Germany
Landon Rieger
Climate Modelling Division, Environment and Climate Change Canada, Victoria BC, Canada
Samuel Ruhl
Atmospheric Chemistry Department, Max Planck Institute for Chemistry, Mainz, Germany
Gregory P. Schill
NOAA Chemical Sciences Laboratory, Boulder, Colorado, USA
Johannes Schneider
Aerosol Chemistry Department, Max Planck Institute for Chemistry, Mainz, Germany
Christiane Schulz
Aerosol Chemistry Department, Max Planck Institute for Chemistry, Mainz, Germany
now at: Leibniz-Zentrum für Agrarlandschaftsforschung (ZALF) e. V., Müncheberg, Germany
Joshua P. Schwarz
NOAA Chemical Sciences Laboratory, Boulder, Colorado, USA
Alexandra P. Tsimpidi
Institute of Climate and Energy Systems: Troposphere (ICE-3), Forschungszentrum Jülich GmbH, Jülich, Germany
Ryan Vella
Atmospheric Chemistry Department, Max Planck Institute for Chemistry, Mainz, Germany
Institute for Physics of the Atmosphere, Johannes Gutenberg University, Mainz, Germany
now at: Institute for Atmospheric and Climate Science, ETH Zurich, Zurich, Switzerland
Christina J. Williamson
Finnish Meteorological Institute, Helsinki, Finland
Institute for Atmospheric and Earth System Research/Physics, Faculty of Science, University of Helsinki, Helsinki, Finland
Yifan Yang
Leibniz Institute for Tropospheric Research (TROPOS), Leipzig, Germany
Daniel Zawada
Institute of Space and Atmospheric Studies, University of Saskatchewan, Saskatchewan, Canada
Jos Lelieveld
Atmospheric Chemistry Department, Max Planck Institute for Chemistry, Mainz, Germany
Climate and Atmosphere Research Center, The Cyprus Institute, Nicosia, Cyprus
Atmospheric Chemistry Department, Max Planck Institute for Chemistry, Mainz, Germany
Climate and Atmosphere Research Center, The Cyprus Institute, Nicosia, Cyprus
Short summary
Aerosols are crucial for Earth's climate, yet their vertical distribution remains poorly understood. We present first consistent global simulations of aerosol distributions and composition from the Earth's surface to the stratosphere, validated by extensive observations. Key findings include a global minimum in aerosol mass in the free troposphere, a significant contribution of organic aerosol in the lower stratosphere, and limited transport of primary particles to the stratosphere.
Aerosols are crucial for Earth's climate, yet their vertical distribution remains poorly...
This manuscript presents a new setup of the EMAC model that allows to seamlessly simulate tropospheric and stratospheric aerosols. Compared to the two standard EMAC versions (one for the troposphere and one for the stratosphere), this new version includes an additional “small coarse” mode for particles between 800 and 3200 nm diameter. The authors evaluate extensively the new model setup against air-, ground-, and satellite-borne observations.
This is an very good model evaluation paper. The new setup is generally well described, the comparison with observations is detailed and rigorous, the text is clear, and the figures are meaningful and very well thought out (I really appreciate how they deliver a lot of information while remaining clearly legible). If this paper was submitted to GMD, I would only have minor comments to improve the readability of the manuscript (see below). However, I don't think this paper is within the scope of ACP (“Articles should have important and clearly argued implications for our understanding of the state and behavior of the atmosphere and climate or present substantial new insights into the atmosphere's role in other parts of the Earth system.”).
General comment: Throughout the manuscript, the references to the relevant figures are generally at the beginning of the section that discuss them. Since each figure has many panels, it would be clearer if the panels were numbered and the text contained the reference to the panels where each of them is discussed. I often had trouble understanding which figure I was supposed to look at while reading the text.
L165: is half-year spin up enough for the stratosphere? If starting from a clear atmosphere, the spin up for the stratosphere is generally several years.
L177: I am a bit confused by the description of the aerosol speciation. Are the concentrations of sulfate, ammonium, nitrate, sodium, chloride, potassium, calcium, magnesium, organic aerosols (separated in 26 species), black carbon, dust, and sea salt prognostically calculated for each of the modes (5 soluble and 5 insoluble modes)? Are soluble species allowed in the insoluble modes to simulate coating?
L230: I think it should be specified that the past studies are only the ones with EMAC.
L250: which parameterization is used for sedimentation? Is it the same for all modes (just varying the radius)?
L265: I don’t understand what “respectively” refers to. Maybe a word is missing?
L291: I am not sure I understand what is done to compare with aircraft measurements. Shouldn’t the aircraft measurement (not the model) be binned on the model vertical levels? Is the vertical distance between consecutive aircraft measurements larger than one model level?
L315: I am surprised that both TROPO and STRATO overestimate NO3, and TS does it better. Is there an explanation for why?
L335: I don’t think MERRA2 is a good benchmark to compare speciation. In MERRA2, the total (not speciated) AOD is assimilated, but the speciation is calculated based on the one of the underlying forecast model (GEOS). If GEOS gets the speciation incorrectly, this error will remain after the assimilation adjust the AOD.
Table 2: generally, M/O is not bad, but R2 is quite low. Can the authors draw any conclusion from this? Could it be that compensating errors in different regions cancel each other, giving a good globally averaged M/O but making the R2 low? It would be interesting to see a map of M/O at each GHOST location: maybe it could show if there are systematic under/overestimation based on the aerosol species dominating PM and give indications on which processes are better simulated.
Fig 3: is “log” in base 10 or e? For clarity, I’d use ln if base e and log_10 if base 10.
L355: why is the pattern opposite in the comparison with MODIS vs AERONET? Is it because MODIS and AERONET are different even when they observe the same locations, or because they measure different locations?
L377 “low M/O … datasets.”: I am not sure I understand this. If concentrations are below the detection limit, are they considered zero or equal to the detection limit? Couldn’t the same detection limit be applied to the model output?
L386: how are biomass burning and volcanic emissions distributed in the vertical?
L486: BC is missing for StratoClim in Fig. 6. Was it not measured?
Fig A1: the vertical labels say PM, but only the sea salt component of PM is shown, correct? Also, I have the same comment as for L335. I don’t think comparing speciation to MERRA2 is useful (and in any case the label on the color calendar should not say “observed” but rather “reanalysis” or “MERRA2”). If GEOS has a bias in sea salt, this bias will remain after assimilating the AOD.