A01: Aerosol, clouds, and radiation characteristics from observations and Big Data analysis

The combination of ground–based remote sensing and radiation measurements, as well as modeling for the PASCAL and MOSAiC expeditions enabled us, for the first time, to resolve the causal relationships between the state of the atmosphere, the properties of aerosol and clouds, and the forcing at the sea ice surface in the Central Arctic during a full annual cycle. In addition to the initial project goals we identified the persistent presence of forest fire smoke in the upper troposphere and lower stratosphere during large parts of MOSAiC. Through case studies, we have described the relationship between the microphysical structure of clouds and the cloud-relevant properties of Arctic aerosol particles. Statistics of the frequency of ice formation in Arctic supercooled clouds revealed that clouds that are coupled to the planetary boundary layer form ice more frequently than free-tropospheric clouds do at similar temperatures. We demonstrated that undetected low-level clouds caused significant errors in the surface radiation closure between simulations using ground-based remote sensing of aerosol and clouds and irradiance (flux densities, hereafter called fluxes) measurements at the ground, and improved the cloud detection accordingly. Ultimately, we obtained unique, continuous time series of Large-Eddy Simulation (LES) runs and height-resolved Cloudnet-based cloud macro- and microphysical properties for the whole MOSAiC period.
For phase III it is planned to bring the aerosol and cloud radiative studies into a larger context, by utilizing the extensive observational and modeling data sets by means of big data approaches. At the foundation of our method is the extensive combined model-observational data set, that will be applied to big data and to regime-based analyses. Radiative closure between observation- and LES-based radiative transfer simulations and surface radiation measurements will quantify uncertainties in our understanding of the Arctic radiation budget. Finally, year-long LES representing both present-day and perturbed MOSAiC climate are subjected to unsupervised and supervised learning and clustering analyses to identify and quantify emergent constraints, guided by climate model data.


Machine learning algorithms and radiative closure help to quantify physical and dynamical emergent constraints affecting Arctic amplification.

Specific research questions in addressing this scientific hypothesis are:

  • What are the contributions of major atmospheric regimes to Arctic aerosol and cloud properties observed during MOSAiC?
  • Can we retrieve the conditions of the atmospheric column accurately enough to achieve a radiative closure for the whole MOSAiC drift experiment?
  • Do the combined high-resolution data sets contain hidden information on fast-acting feedback mechanisms that function as emergent constraints on Arctic amplification?

A regime-based characterization of aerosol-cloud-radiation relations directly addresses the role of aerosols and clouds in the current and (by means of regime shifts) future Arctic surface radiative forcing (SQ1). Connecting the regimes to long-range transports of aerosols and humidity meets SQ2. Finally, SQ3 is addressed by identifying emergent constraints.

Achievements phase II

  • Surface-coupling effects on Arctic clouds were found to increase the occurrence of heterogeneously formed ice at low sub-zero temperatures
  • Development of a robust model workflow for the accurate Large-Eddy Simulation (LES) of Arctic mixed-phase clouds based on observations-based calibration
  • Generation of drift-long MOSAiC datasets of both daily LES and the time-height-resolved Cloudnet product of cloud microphysical properties, based on RV Polarstern observations

Achievements phase I

A01 collected remote sensing measurements of vertical proiles of aerosol and cloud properties under different meteorological conditions during PASCAL (Knudsen et al., 2018a; Wendisch et al., 2019; Radenz et al., 2019). From the data, the aerosol and cloud radiative forcing at the surface was derived (Barrientos Velasco et al., 2019). A distinct difference in the temperature for ice formation between clouds coupled to and decoupled from the surface was discovered. From the simulations, constrained by the observations, new insights into local and remote controls of clouds and radiation in the Arctic were obtained (Neggers et al., 2019). The experience made during the observations helped to refine and further develop the techniques, which will allow improved microphysical characterisations of mixed–phase cloud layers during phase II.

Role within (AC)³

Collabortion Matrix Phase III_A01


Niklas Schnierstein


University of Cologne
Institute for Geophysics and Meteorology (IGM)
Pohligstr. 3
50969 Cologne


will follow


Dr. Carola Barrientos Velasco

Postdoc (associated)

Leibniz Institute for Tropospheric Research (TROPOS)
Permoserstr. 15
04318 Leipzig


++49 (0) 341 2717 7359




Prof. Dr. Andreas Macke

Principal Investigator

Leibniz Institute for Tropospheric Research (TROPOS)
Permoserstr. 15
04318 Leipzig


++49 (0) 341 2717 7060




Prof. Dr. Roel Neggers

Principal Investigator

University of Cologne
Institute for Geophysics and Meteorology (IGM)
Pohligstr. 3
50969 Cologne


++49 (0) 221 4701614



Hannes Griesche vom TROPOS vor dem Wolkenradar. In dem Schrank befindet sich eine Stabilisierungsplattform, welche die Schiffsbewegungen ausgleicht, so dass das Radar jederzeit senkrecht in den Himmel schaut. Foto: Carola Barrientos, TROPOS

Dr. Hannes Griesche


Leibniz Institute for Tropospheric Research (TROPOS)
Permoserstr. 15
04318 Leipzig







Griesche, H.J., Seifert, P., Engelmann, R., M. Radenz, J. Hofer, D. Althausen, A. Walbröl, C. Barrientos-Velasco, H. Baars, S. Dahlke, S. Tukiainen & A. Macke, 2024, Cloud micro- and macrophysical properties from ground-based remote sensing during the MOSAiC drift experiment. Sci Data 11, 505. https://doi.org/10.1038/s41597-024-03325-w

Griesche, H. J., Barrientos-Velasco, C., Deneke, H., Hünerbein, A., Seifert, P., and Macke, A., 2024: Low-level Arctic clouds: a blind zone in our knowledge of the radiation budget, Atmos. Chem. Phys., 24, 597–612, https://doi.org/10.5194/acp-24-597-2024.


Kecorius, S.; Hoffmann, E. H.; Tilgner, A.; Barrientos-Velasco, C.; van Pinxteren, M.; Zeppenfeld, S.; Vogl, T.; Madueño, L.; Lovrić, M.; Wiedensohler, A.; Kulmala, M.; Paasonen, P. & Herrmann, H., 2023: Rapid growth of Aitken-mode particles during Arctic summer by fog chemical processing and its implication, PNAS Nexus, 10.1093/pnasnexus/pgad124

Saavedra Garfias, P., Kalesse-Los, H., von Albedyll, L., Griesche, H., and Spreen, G., 2023: Asymmetries in cloud microphysical properties ascribed to sea ice leads via water vapour transport in the central Arctic, Atmos. Chem. Phys., 23, 14521–14546, https://doi.org/10.5194/acp-23-14521-2023.

Ansmann, A.; Ohneiser, K.; Engelmann, R.; Radenz, M.; Griesche, H.; Hofer, J.; Althausen, D.; Creamean, J. M.; Boyer, M. C.; Knopf, D. A.; Dahlke, S.; Maturilli, M.; Gebauer, H.; Bühl, J.; Jimenez, C.; Seifert, P. & Wandinger, U., 2023: Annual cycle of aerosol properties over the central Arctic during MOSAiC 2019–2020 — light-extinction, CCN, and INP levels from the boundary layer to the tropopause, Atmos. Chem. Phys., 23, 12821–12849, https://doi.org/10.5194/acp-23-12821-2023

Kirbus, B.; Tiedeck, S.; Camplani, A.; Chylik, J.; Crewell, S.; Dahlke, S.; Ebell, K.; Gorodetskaya, I.; Griesche, H.; Handorf, D.; Höschel, I.; Lauer, M.; Neggers, R.; Rückert, J.; Shupe, M. D.; Spreen, G.; Walbröl, A.; Wendisch, M. & Rinke, A., 2023: Surface impacts and associated mechanisms of a moisture intrusion into the Arctic observed in mid-April 2020 during MOSAiC, Front. Earth Sci., 11, https://doi.org/10.3389/feart.2023.1147848

Wendisch, M.; Brückner, M.; Crewell, S.; Ehrlich, A.; Notholt, J.; Lüpkes, C.; Macke, A.; Burrows, J. P.; Rinke, A.; Quaas, J.; Maturilli, M.; Schemann, V.; Shupe, M. D.; Akansu, E. F.; Barrientos-Velasco, C.; Bärfuss, K.; Blechschmidt, A.-M.; Block, K.; Bougoudis, I.; Bozem, H.; Böckmann, C.; Bracher, A.; Bresson, H.; Bretschneider, L.; Buschmann, M.; Chechin, D. G.; Chylik, J.; Dahlke, S.; Deneke, H.; Dethloff, K.; Donth, T.; Dorn, W.; Dupuy, R.; Ebell, K.; Egerer, U.; Engelmann, R.; Eppers, O.; Gerdes, R.; Gierens, R.; Gorodetskaya, I. V.; Gottschalk, M.; Griesche, H.; Gryanik, V. M.; Handorf, D.; Harm-Altstädter, B.; Hartmann, J.; Hartmann, M.; Heinold, B.; Herber, A.; Herrmann, H.; Heygster, G.; Höschel, I.; Hofmann, Z.; Hölemann, J.; Hünerbein, A.; Jafariserajehlou, S.; Jäkel, E.; Jacobi, C.; Janout, M.; Jansen, F.; Jourdan, O.; Jurányi, Z.; Kalesse-Los, H.; Kanzow, T.; Käthner, R.; Kliesch, L. L.; Klingebiel, M.; Knudsen, E. M.; Kovács, T.; Körtke, W.; Krampe, D.; Kretzschmar, J.; Kreyling, D.; Kulla, B.; Kunkel, D.; Lampert, A.; Lauer, M.; Lelli, L.; von Lerber, A.; Linke, O.; Löhnert, U.; Lonardi, M.; Losa, S. N.; Losch, M.; Maahn, M.; Mech, M.; Mei, L.; Mertes, S.; Metzner, E.; Mewes, D.; Michaelis, J.; Mioche, G.; Moser, M.; Nakoudi, K.; Neggers, R.; Neuber, R.; Nomokonova, T.; Oelker, J.; Papakonstantinou-Presvelou, I.; Pätzold, F.; Pefanis, V.; Pohl, C.; van Pinxteren, M.; Radovan, A.; Rhein, M.; Rex, M.; Richter, A.; Risse, N.; Ritter, C.; Rostosky, P.; Rozanov, V. V.; Donoso, E. R.; Saavedra-Garfias, P.; Salzmann, M.; Schacht, J.; Schäfer, M.; Schneider, J.; Schnierstein, N.; Seifert, P.; Seo, S.; Siebert, H.; Soppa, M. A.; Spreen, G.; Stachlewska, I. S.; Stapf, J.; Stratmann, F.; Tegen, I.; Viceto, C.; Voigt, C.; Vountas, M.; Walbröl, A.; Walter, M.; Wehner, B.; Wex, H.; Willmes, S.; Zanatta, M. & Zeppenfeld, S., 2023: Atmospheric and Surface Processes, and Feedback Mechanisms Determining Arctic Amplification: A Review of First Results and Prospects of the (AC)³ Project, Bull. Am. Meteorol. Soc., American Meteorological Society, 104, E208–E242, https://doi.org/10.1175/bams-d-21-0218.1

Linke, O., Quaas, J., Baumer, F., Becker, S., Chylik, J., Dahlke, S., Ehrlich, A., Handorf, D., Jacobi, C., Kalesse-Los, H., Lelli, L., Mehrdad, S., Neggers, R. A. J., Riebold, J., Saavedra Garfias, P., Schnierstein, N., Shupe, M. D., Smith, C., Spreen, G., Verneuil, B., Vinjamuri, K. S., Vountas, M., and Wendisch, M., 2023: Constraints on simulated past Arctic amplification and lapse rate feedback from observations, Atmos. Chem. Phys., 23, 9963–9992, https://doi.org/10.5194/acp-23-9963-2023.

Chylik, J., Chechin, D., Dupuy, R., Kulla, B. S., Lüpkes, C., Mertes, S., Mech, M., and Neggers, R. A. J., 2023: Aerosol impacts on the entrainment efficiency of Arctic mixed-phase convection in a simulated air mass over open water, Atmos. Chem. Phys., https://doi.org/10.5194/acp-23-4903-2023.


M. Lonardi, C. Pilz, E. F. Akansu, S. Dahlke, U. Egerer, A. Ehrlich, H. Griesche, A. J. Heymsfield, B. Kirbus, C. G. Schmitt, M. D. Shupe, H. Siebert, B. Wehner, M. Wendisch, 2022; Tethered balloon-borne profile measurements of atmospheric properties in the cloudy atmospheric boundary layer over the Arctic sea ice during MOSAiC: Overview and first results. Elementa: Science of the Anthropocene; 10 (1): 000120. doi: https://doi.org/10.1525/elementa.2021.000120

Barrientos Velasco, C., 2022: Radiative effects of clouds in the Arctic, Dissertation, Universität Leipzig, https://nbn-resolving.org/urn:nbn:de:bsz:15-qucosa2-821848

Barrientos-Velasco, C., Deneke, H., Hünerbein, A., Griesche, H. J., Seifert, P., and Macke, A., 2022: Radiative closure and cloud effects on the radiation budget based on satellite and shipborne observations during the Arctic summer research cruise, PS106, Atmos. Chem. Phys., 22, 9313–9348, https://doi.org/10.5194/acp-22-9313-2022.

Richter, P., Palm, M., Weinzierl, C., Griesche, H., Rowe, P. M., and Notholt, J., 2022: A dataset of microphysical cloud parameters, retrieved from Fourier-transform infrared (FTIR) emission spectra measured in Arctic summer 2017, Earth Syst. Sci. Data, 14, 2767–2784, https://doi.org/10.5194/essd-14-2767-2022.

Griesche, H., 2022: Arctic low-level mixed-phase clouds and their complex interactions with aerosol and radiation – Remote sensing of the Arctic troposphere with the shipborne supersite OCEANET-Atmosphere, Dissertation, Universität Leipzig, https://nbn-resolving.org/urn:nbn:de:bsz:15-qucosa2-797651

Geerts, B.; Giangrande, S. E.; McFarquhar, G. M.; Xue, L.; Abel, S. J.; Comstock, J. M.; Crewell, S.; DeMott, P. J.; Ebell, K.; Field, P.; Hill, T. C. J.; Hunzinger, A.; Jensen, M. P.; Johnson, K. L.; Juliano, T. W.; Kollias, P.; Kosovic, B.; Lackner, C.; Luke, E.; Lüpkes, C.; Matthews, A. A.; Neggers, R.; Ovchinnikov, M.; Powers, H.; Shupe, M. D.; Spengler, T.; Swanson, B. E.; Tjernström, M.; Theisen, A. K.; Wales, N. A.; Wang, Y.; Wendisch, M. & Wu, P., 2022: The COMBLE Campaign: A Study of Marine Boundary Layer Clouds in Arctic Cold-Air Outbreaks, Bull. Am. Meteorol. Soc., 103, E1371 – E1389, https://doi.org/10.1175/BAMS-D-21-0044.1

Walbröl, A., Crewell, S., Engelmann, R., Orlandi, E., Grische, H., Radenz, M., Hofer, J., Althausen, D., Maturilli, M. & Ebell, K., 2022: Atmospheric temperature, water vapour and liquid water path from two microwave radiometers during MOSAiC. Sci Data 9, 534. https://doi.org/10.1038/s41597-022-01504-1


Shupe, M.D., M. Rex, B. Blomquist, P.O.G. Persson, J. Schmale, T. Uttal, D. Althausen, H. Angot, S. Archer, L. Bariteau, I. Beck, J. Bilberry, S. Bussi, C. Buck, M. Boyer, Z. Brasseur, I.M. Brooks, R. Calmer, J. Cassano, V. Castro, D. Chu, D. Costa, C.J. Cox, J. Creamean, S. Crewell, S. Dahlke, E. Damm, G. de Boer, H. Deckelmann, K. Dethloff, M. Dütsch, K. Ebell, A. Ehrlich, J. Ellis, R. Engelmann, A.A. Fong, M.M. Frey, M.R. Gallagher, L. Ganzeveld, R. Gradinger, J. Graeser, V. Greenamyer, H. Griesche, S. Griffiths, J. Hamilton, G. Heinemann, D. Helmig, A. Herber, C. Heuzé, J. Hofer, T. Houchens, D. Howard, J. Inoue, H.-W. Jacobi, R. Jaiser, T. Jokinen, O. Jourdan, G. Jozef, W. King, A. Kirchgaessner, M. Klingebiel, M. Krassovski, T. Krumpen, A. Lampert, W. Landing, T. Laurila, D. Lawrence, B. Loose, M. Lonardi, C. Lüpkes, M. Maahn, A. Macke, W. Maslowski, C. Marsay, M. Maturilli, M. Mech, S. Morris, M. Moser, M. Nicolaus, P. Ortega, J. Osborn, F. Pätzold, D.K. Perovich, T. Petäjä, C. Pilz, R. Pirazzini, K. Posman, H. Powers, K.A. Pratt, A. Preußer, L. Quéléver, M. Radenz, B. Rabe, A. Rinke, T. Sachs, A. Schulz, H. Siebert, T. Silva, A. Solomon, A. Sommerfeld, G. Spreen, M. Stephens, A. Stohl, G. Svensson, J. Uin, J. Viegas, C. Voigt, P. von der Gathen, B. Wehner, J.M. Welker, M. Wendisch, M. Werner, Z. Xie, F. Yue, 2022: Overview of the MOSAiC expedition – Atmosphere.  Elementa: Science of the Anthropocene, 10 (1): 00060, https://doi.org/10.1525/elementa.2021.00060.


Gryanik, V. M., Lüpkes, C., Sidorenko, D., and Grachev, A., 2021. A universal approach for the non-iterative parametrization of near-surface turbulent fluxes in climate and weather prediction models. J. Adv. Model. Earth Syst., 13, e2021MS002590. https://doi.org/10.1029/2021MS002590

Ohneiser, K., Ansmann, A., Chudnovsky, A., Engelmann, R., Ritter, C., Veselovskii, I., Baars, H., Gebauer, H., Griesche, H., Radenz, M., Hofer, J., Althausen, D., Dahlke, S., and Maturilli, M., 2021: The unexpected smoke layer in the High Arctic winter stratosphere during MOSAiC 2019–2020 , Atmos. Chem. Phys., 21, 15783–15808, https://doi.org/10.5194/acp-21-15783-2021.

Engelmann, R., Ansmann, A., Ohneiser, K., Griesche, H., Radenz, M., Hofer, J., Althausen, D., Dahlke, S., Maturilli, M., Veselovskii, I., Jimenez, C., Wiesen, R., Baars, H., Bühl, J., Gebauer, H., Haarig, M., Seifert, P., Wandinger, U., and Macke, A., 2021: Wildfire smoke, Arctic haze, and aerosol effects on mixed-phase and cirrus clouds over the North Pole region during MOSAiC: an introduction, Atmos. Chem. Phys., 21, 13397–13423, https://doi.org/10.5194/acp-21-13397-2021.

Griesche, H. J., Ohneiser, K., Seifert, P., Radenz, M., Engelmann, R., and Ansmann, A., 2021: Contrasting ice formation in Arctic clouds: surface-coupled vs. surface-decoupled clouds, Atmos. Chem. Phys., 21, 10357–10374, https://doi.org/10.5194/acp-21-10357-2021.

Egerer, U., Ehrlich, A., Gottschalk, M., Griesche, H., Neggers, R. A. J., Siebert, H., and Wendisch, M., 2021: Case study of a humidity layer above Arctic stratocumulus and potential turbulent coupling with the cloud top, Atmos. Chem. Phys., 21, 6347–6364, https://doi.org/10.5194/acp-21-6347-2021.

Wendisch, M., D. Handorf, I. Tegen, R. A. J. Neggers, and G. Spreen, 2021, Glimpsing the ins and outs of the Arctic atmospheric cauldron, Eos, 102, https://doi.org/10.1029/2021EO155959. Published on 16 March 2021.


Griesche, H. J., Seifert, P., Ansmann, A., Baars, H., Barrientos Velasco, C., Bühl, J., Engelmann, R., Radenz, M., Zhenping, Y., and Macke, A., 2020: Application of the shipborne remote sensing supersite OCEANET for profiling of Arctic aerosols and clouds during Polarstern cruise PS106, Atmos. Meas. Tech., 13, 5335–5358, https://doi.org/10.5194/amt-13-5335-2020.

Barrientos Velasco, C., Deneke, H., Griesche, H., Seifert, P., Engelmann, R., and Macke, A., 2020: Spatiotemporal variability of solar radiation introduced by clouds over Arctic sea ice, Atmos. Meas. Tech., 13, 1757–1775, https://doi.org/10.5194/amt-13-1757-2020.


Radenz, M., J. Bühl, P. Seifert, H. Griesche, and R. Engelmann, 2019: peakTree: A framework for structure-preserving radar Doppler spectra analysis, Atmos. Meas. Tech.12, 4813–4828, doi:10.5194/amt-12-4813-2019

Neggers, R. A. J., J. Chylík, U. Egerer, H. Griesche, V. Schemann, P. Seifert, H. Siebert and A. Macke, 2019:
Local and remote controls on Arctic mixed-layer evolution, accepted for publication in J. Adv. Mod. Earth Syst.doi:10.1029/2019MS001671

Wendisch, M., A. Macke, A. Ehrlich, C. Lüpkes, M. Mech, D. Chechin, K. Dethloff, C. Barrientos, H. Bozem, M. Brückner, H.-C. Clemen, S. Crewell, T. Donth, R. Dupuy, C. Dusny, K. Ebell, U. Egerer, R. Engelmann, C. Engler, O. Eppers, M. Gehrmann, X. Gong, M. Gottschalk, C. Gourbeyre, H. Griesche, J. Hartmann, M. Hartmann, B. HeinoldA. Herber, H. Herrmann, G. Heygster, P. Hoor, S. Jafariserajehlou, E. Jäkel, E. Järvinen, O. Jourdan, U. Kästner, S. Kecorius, E.M. Knudsen, F. Köllner, J. Kretzschmar, L. Lelli, D. Leroy, M. Maturilli, L. Mei, S. Mertes, G. Mioche, R. Neuber, M. Nicolaus, T. Nomokonova, J. Notholt, M. Palm, M. van Pinxteren, J. Quaas, P. Richter, E. Ruiz-Donoso, M. Schäfer, K. Schmieder, M. Schnaiter, J. Schneider, A. Schwarzenböck, P. Seifert, M.D. Shupe, H. Siebert, G. Spreen, J. Stapf, F. Stratmann, T. Vogl, A. Welti, H. Wex, A. Wiedensohler, M. Zanatta, S. Zeppenfeld, 2019: The Arctic Cloud Puzzle: Using ACLOUD/PASCAL Multi-Platform Observations to Unravel the Role of Clouds and Aerosol Particles in Arctic Amplification, Bull. Amer. Meteor. Soc., 100 (5), 841–871, doi:10.1175/BAMS-D-18-0072.1


Knudsen, E.M., B. Heinold, S. Dahlke, H. Bozem, S. Crewell, I. V. Gorodetskaya, G. Heygster, D. Kunkel, M. MaturilliM. Mech, C. Viceto, A. Rinke, H. Schmithüsen, A. Ehrlich, A. Macke, C. Lüpkes, M. Wendisch, 2018: Meteorological conditions during the ACLOUD/PASCAL field campaign near Svalbard in early summer 2017, Atmos. Chem. Phys., 18, 17995-18022, doi:10.5194/acp-18-17995-2018

Wegmann, M., Orsolini, Y., V´azquez, M., Gimeno, L., Nieto, R., Bulygina, O., Jaiser, R., Handorf, D., Rinke, A., Dethloff, K., Sterin, A., and Brönnimann, S.: Arctic moisture source for Eurasian snow cover variations in autumn, Environ. Res. Lett., 10, 054015, doi:10.1088/1748-9326/10/5/054015, 2015.

Project Poster

 Phase III Evaluation poster 2023

 Phase II Evaluation poster 2019

 Phase I Evaluation poster 2015