Hypothesis:

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 profiles 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

Project Posters

Phase III Evaluation poster 2023	Phase II Evaluation poster 2019	Phase I Evaluation poster 2015

Project Members

Publications

2026

2025

Neggers, R. A. J., Chylik, J., and Schnierstein, N. , June 2025: The entrainment efficiency of persistent arctic mixed-phase clouds as inferred from daily large-eddy simulations during the MOSAiC drift. J. Atmospheric Sci., 82(6):1195–1213, doi:10.1175/JAS-D-24-0188.1

Ansmann, A., Jimenez, C., Knopf, D. A., Roschke, J., Bühl, J., Ohneiser, K., and Engelmann, R. , May 2025: Impact of wildfire smoke on Arctic cirrus formation - Part 2: Simulation of MOSAiC 2019-2020 cases. Atmospheric Chem. Phys., 25(9):4867–4884, doi:10.5194/acp-25-4867-2025

Seidel, C., Althausen, D., Ansmann, A., Wendisch, M., Griesche, H., Radenz, M., Hofer, J., Dahlke, S., Maturilli, M., Walbröl, A., Baars, H., and Engelmann, R. , April 2025: Close correlation between vertically integrated tropospheric water vapor and the downward, broadband thermal-infrared irradiance at the ground: Observations in the central arctic during MOSAiC. J. Geophys. Res.-Atmospheres, doi:10.1029/2024JD042378

Ehrlich, A., Crewell, S., Herber, A., Klingebiel, M., Lüpkes, C., Mech, M., Becker, S., Borrmann, S., Bozem, H., Buschmann, M., Clemen, H., De La Torre Castro, E., Dorff, H., Dupuy, R., Eppers, O., Ewald, F., George, G., Giez, A., Grawe, S., Gourbeyre, C., Hartmann, J., Jäkel, E., Joppe, P., Jourdan, O., Jurányi, Z., Kirbus, B., Lucke, J., Luebke, A. E., Maahn, M., Maherndl, N., Mallaun, C., Mayer, J., Mertes, S., Mioche, G., Moser, M., Müller, H., Pörtge, V., Risse, N., Roberts, G., Rosenburg, S., Röttenbacher, J., Schäfer, M., Schaefer, J., Schäfler, A., Schirmacher, I., Schneider, J., Schnitt, S., Stratmann, F., Tatzelt, C., Voigt, C., Walbröl, A., Weber, A., Wetzel, B., Wirth, M., and Wendisch, M. , April 2025: A Comprehensive in Situ and Remote Sensing Data Set Collected during the HALO–(A C)\textsuperscript3 Aircraft Campaign. Earth Syst. Sci. Data, 17(3):1295–1328, doi:10.5194/essd-17-1295-2025

Barrientos-Velasco, C., Cox, C. J., Deneke, H., Dodson, J. B., Hünerbein, A., Shupe, M. D., Taylor, P. C., and Macke, A. , April 2025: Estimation of the radiation budget during MOSAiC based on ground-based and satellite remote sensing observations. Atmospheric Chem. Phys., 25(7):3929–3960, doi:10.5194/acp-25-3929-2025

Jimenez, C., Ansmann, A., Ohneiser, K., Griesche, H., Engelmann, R., Radenz, M., Hofer, J., Althausen, D., Knopf, D. A., Dahlke, S., Bühl, J., Baars, H., Seifert, P., and Wandinger, U. , 2025: MOSAiC studies of long-lasting mixed-phase cloud events and analysis of the liquid-phase properties of Arctic clouds. Atmospheric Chem. Phys., 25(20):12955–12981, doi:10.5194/acp-25-12955-2025

Ansmann, A., Jimenez, C., Roschke, J., Bühl, J., Ohneiser, K., Engelmann, R., Radenz, M., Griesche, H., Hofer, J., Althausen, D., Knopf, D. A., Dahlke, S., Gaudek, T., Seifert, P., and Wandinger, U. , 2025: Impact of wildfire smoke on Arctic cirrus formation – Part 1: Analysis of MOSAiC 2019–2020 observations. Atmos. Chem. Phys., 25(9):4847–4866, doi:10.5194/acp-25-4847-2025

2024

Walbröl, A., Griesche, H. J., Mech, M., Crewell, S., and Ebell, K. , October 2024: Combining Low- and High-Frequency Microwave Radiometer Measurements from the MOSAiC Expedition for Enhanced Water Vapour Products. Atmospheric Meas. Tech., 17(20):6223–6245, doi:10.5194/amt-17-6223-2024

Griesche, H. J., Seifert, P., Engelmann, R., Radenz, M., Hofer, J., Althausen, D., Walbröl, A., Barrientos-Velasco, C., Baars, H., Dahlke, S., Tukiainen, S., and Macke, A. , May 2024: Cloud Micro- and Macrophysical Properties from Ground-Based Remote Sensing during the MOSAiC Drift Experiment. Sci. Data, 11(1):505, doi:10.1038/s41597-024-03325-w

Griesche, H. J., Barrientos-Velasco, C., Deneke, H., Hünerbein, A., Seifert, P., and Macke, A. , January 2024: Low-Level Arctic Clouds: A Blind Zone in Our Knowledge of the Radiation Budget. Atmospheric Chem. Phys., 24(1):597–612, doi:10.5194/acp-24-597-2024

Schnierstein, N., Chylik, J., Shupe, M. D., and Neggers, R. A. J. , 2024: Standardized daily high-resolution large-eddy simulations of the arctic boundary layer and clouds during the complete MOSAiC drift. J. Adv. Model. Earth Syst., 16(11):e2024MS004296, doi:10.1029/2024MS004296

Paulus, F. M., Karalis, M., George, G., Svensson, G., Wendisch, M., and Neggers, R. A. J. , 2024: Airborne measurements of mesoscale divergence at high latitudes during HALO–(AC)3. J. Atmos. Sci., 81(12):2051–2067, doi:10.1175/JAS-D-24-0034.1

2023

Saavedra Garfias, P., Kalesse-Los, H., Von Albedyll, L., Griesche, H., and Spreen, G. , November 2023: Asymmetries in Cloud Microphysical Properties Ascribed to Sea Ice Leads via Water Vapour Transport in the Central Arctic. Atmospheric Chem. Phys., 23(22):14521–14546, doi: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., and Wandinger, U. , October 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. Atmospheric Chem. Phys., 23(19):12821–12849, doi:10.5194/acp-23-12821-2023

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. , September 2023: Constraints on Simulated Past Arctic Amplification and Lapse Rate Feedback from Observations. Atmospheric Chem. Phys., 23(17):9963–9992, doi:10.5194/acp-23-9963-2023

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., and Herrmann, H. , May 2023: Rapid Growth of Aitken-mode Particles during Arctic Summer by Fog Chemical Processing and Its Implication. PNAS Nexus, 2(5):pgad124, doi:10.1093/pnasnexus/pgad124

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., and Rinke, A. , April 2023: Surface Impacts and Associated Mechanisms of a Moisture Intrusion into the Arctic Observed in Mid-April 2020 during MOSAiC. Front. Earth Sci., 11:1147848, doi:10.3389/feart.2023.1147848

Chylik, J., Chechin, D., Dupuy, R., Kulla, B. S., Lüpkes, C., Mertes, S., Mech, M., and Neggers, R. A. J. , April 2023: Aerosol Impacts on the Entrainment Efficiency of Arctic Mixed-Phase Convection in a Simulated Air Mass over Open Water. Atmospheric Chem. Phys., 23(8):4903–4929, doi:10.5194/acp-23-4903-2023

2022

Walbröl, A., Crewell, S., Engelmann, R., Orlandi, E., Griesche, H., Radenz, M., Hofer, J., Althausen, D., Maturilli, M., and Ebell, K. , September 2022: Atmospheric Temperature, Water Vapour and Liquid Water Path from Two Microwave Radiometers during MOSAiC. Sci. Data, 9(1):534, doi:10.1038/s41597-022-01504-1

Lonardi, M., Pilz, C., Akansu, E. F., Dahlke, S., Egerer, U., Ehrlich, A., Griesche, H., Heymsfield, A. J., Kirbus, B., Schmitt, C. G., Shupe, M. D., Siebert, H., Wehner, B., and Wendisch, M. , September 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. Elem. Sci. Anthr., 10(1):000120, doi:10.1525/elementa.2021.000120

Barrientos-Velasco, C., Deneke, H., Hünerbein, A., Griesche, H. J., Seifert, P., and Macke, A. , July 2022: Radiative Closure and Cloud Effects on the Radiation Budget Based on Satellite and Shipborne Observations during the Arctic Summer Research Cruise, PS106. Atmospheric Chem. Phys., 22(14):9313–9348, doi:10.5194/acp-22-9313-2022

Richter, P., Palm, M., Weinzierl, C., Griesche, H., Rowe, P. M., and Notholt, J. , June 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(6):2767–2784, doi:10.5194/essd-14-2767-2022

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., and Wu, P. , May 2022: The COMBLE Campaign: A Study of Marine Boundary Layer Clouds in Arctic Cold-Air Outbreaks. Bull. Am. Meteorol. Soc., 103(5):E1371–E1389, doi:10.1175/BAMS-D-21-0044.1

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

2021

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. , October 2021: The Unexpected Smoke Layer in the High Arctic Winter Stratosphere during MOSAiC 2019–2020. Atmospheric Chem. Phys., 21(20):15783–15808, doi: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. , September 2021: Wildfire Smoke, Arctic Haze, and Aerosol Effects on Mixed-Phase and Cirrus Clouds over the North Pole Region during MOSAiC: An Introduction. Atmospheric Chem. Phys., 21(17):13397–13423, doi:10.5194/acp-21-13397-2021

Gryanik, V. M., Lüpkes, C., Sidorenko, D., and Grachev, A. , August 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(8):e2021MS002590, doi:10.1029/2021MS002590

Griesche, H. J., Ohneiser, K., Seifert, P., Radenz, M., Engelmann, R., and Ansmann, A. , July 2021: Contrasting Ice Formation in Arctic Clouds: Surface-Coupled vs. Surface-Decoupled Clouds. Atmospheric Chem. Phys., 21(13):10357–10374, doi:10.5194/acp-21-10357-2021

Egerer, U., Ehrlich, A., Gottschalk, M., Griesche, H., Neggers, R. A. J., Siebert, H., and Wendisch, M. , April 2021: Case Study of a Humidity Layer above Arctic Stratocumulus and Potential Turbulent Coupling with the Cloud Top. Atmospheric Chem. Phys., 21(8):6347–6364, doi:10.5194/acp-21-6347-2021

Wendisch, M., Handorf, D., Tegen, I., Neggers, R., and Spreen, G. , March 2021: Glimpsing the Ins and Outs of the Arctic Atmospheric Cauldron. Eos, doi:10.1029/2021EO155959

2020

Griesche, H. J., Seifert, P., Ansmann, A., Baars, H., Barrientos Velasco, C., Bühl, J., Engelmann, R., Radenz, M., Zhenping, Y., and Macke, A. , October 2020: Application of the Shipborne Remote Sensing Supersite OCEANET for Profiling of Arctic Aerosols and Clouds during \emphPolarstern Cruise PS106. Atmospheric Meas. Tech., 13(10):5335–5358, doi:10.5194/amt-13-5335-2020

Barrientos Velasco, C., Deneke, H., Griesche, H., Seifert, P., Engelmann, R., and Macke, A. , April 2020: Spatiotemporal Variability of Solar Radiation Introduced by Clouds over Arctic Sea Ice. Atmospheric Meas. Tech., 13(4):1757–1775, doi:10.5194/amt-13-1757-2020

2019

Radenz, M., Bühl, J., Seifert, P., Griesche, H., and Engelmann, R. , September 2019: peakTree: A Framework for Structure-Preserving Radar Doppler Spectra Analysis. Atmospheric Meas. Tech., 12(9):4813–4828, doi:10.5194/amt-12-4813-2019

Neggers, R. A. J., Chylik, J., Egerer, U., Griesche, H., Schemann, V., Seifert, P., Siebert, H., and Macke, A. , July 2019: Local and Remote Controls on Arctic Mixed-Layer Evolution. J. Adv. Model. Earth Syst., 11(7):2214–2237, doi:10.1029/2019MS001671

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

2018

Knudsen, E. M., Heinold, B., Dahlke, S., Bozem, H., Crewell, S., Gorodetskaya, I. V., Heygster, G., Kunkel, D., Maturilli, M., Mech, M., Viceto, C., Rinke, A., Schmithüsen, H., Ehrlich, A., Macke, A., Lüpkes, C., and Wendisch, M. , December 2018: Meteorological Conditions during the ACLOUD/PASCAL Field Campaign near Svalbard in Early Summer 2017. Atmospheric Chem. Phys., 18(24):17995–18022, doi:10.5194/acp-18-17995-2018

2017

2016