Hypothesis:

Advanced representations of Arctic processes in a global climate model improve the representation of Arctic-midlatitude linkages.

Specifically we want to answer the following questions:

• How sensitive is the simulated Arctic climate to changes of surface-related and gravity wave parameterizations?
• How does a better representation of Arctic processes in a global climate model impact the representation of Arctic-midlatitude linkages under present day climate?
• Will a better representation of Arctic processes in a global climate model lead to significant changes in Arctic-midlatitude linkages under future climate conditions?

To answer these questions, we will implement improved physical parameterizations of boundary layer turbulence, surface drag, surface albedo, and gravity wave drag developed previously within (AC)³ into the global ICON model; perform sensitivity simulations for present-day and future climate conditions with the ICON standard version, and with improved parameterizations; evaluate and quantify dynamical processes of Arctic climate change, Arctic amplification and Arctic-midlatitude linkages exploiting reanalyses and (AC)³ observations by applying the methods developed in project D01 during phases I and II. This work plan relates to all of the strategic questions. We will analyze the contributions of new parameterizations to Arctic amplification (SQ1), quantify the effect on Arctic-midlatitude linkages (SQ2) and analyze their role in the future Arctic amplification evolution (SQ3).

Achievements phase II

• Analysis of the role of horizontal energy transports to synoptic events and LRF.
• Unraveling the impact of changing SIC and SSTs on Arctic-midlatitude linkages including extremes.
• Updated GW representation improves stratospheric circulation in ICON.
• New machine learning methods for circulation pattern detection and analysis.

Achievements phase I

D01 has analysed the horizontal transports of moist static energy into the Arctic using an innovative, self-organising maps algorithm (Mewes and Jacobi, 2019). The impact of Arctic sea-ice decline on the large-scale atmospheric circulation has been analysed in reanalysis data and climate model simulations (Romanowsky et al., 2019). A tropospheric pathway mainly occurs in autumn to early winter and results in more frequent occurrence of blockings over Scandinavia and northern Eurasia. This initiates a stratospheric pathway with enhanced upward propagation of energy to weaken the stratospheric polar vortex. The subsequent downward propagation of these stratospheric circulation anomalies in late winter (Jaiser et al., 2016) contributes to persistent negative North Atlantic Oscillation (NAO) anomalies. An improvement of modelled stratospheric pathway for Arctic-mid-latitude linkages by including interactive stratospheric ozone chemistry into general circulation models was achieved (Romanowsky et al., 2019).

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

Mehrdad, S., Marjani, S., Handorf, D., and Jacobi, C. , 2026: Northern Hemisphere stratospheric polar vortex morphology under localized gravity wave forcing: a shape-based classification. Atmos. Chem. Phys., 26(5):3391–3415, doi:10.5194/acp-26-3391-2026

2025

Zhang, X., Vihma, T., Rinke, A., Moore, G. W. K., Tang, H., Äijälä, C., DuVivier, A., Huang, J., Landrum, L., Li, C., Zhang, J., Boisvert, L., Cheng, B., Cohen, J., Handorf, D., Hanna, E., Hartmuth, K., Jonassen, M. O., Luo, Y., Murto, S., Overland, J. E., Parker, C., Perrie, W., Schulz, K., Schweiger, A., Spengler, T., Steele, M., Tung, W., Tyrrell, N., Valkonen, E., Wang, H., Wang, Z., Weijer, W., Wickström, S., Wu, Y., and Zhang, M. , October 2025: Weather and climate extremes in a changing Arctic. Nature Reviews Earth & Environment, doi:10.1038/s43017-025-00724-4

Kumar, A., Karami, K., Jacobi, C., and Mehrdad, S. , August 2025: Exploring the impact of orographic and non-orographic gravity waves on arctic stratospheric polar vortex dynamics and springtime ozone loss. J. Atmospheric Sol.-Terr. Phys., doi:10.1016/j.jastp.2025.106538

Mehrdad, S., Marjani, S., Handorf, D., and Jacobi, C. , 2025: Non-zonal gravity wave forcing of the Northern Hemisphere winter circulation and effects on middle atmosphere dynamics. Weather Clim. Dyn., 6(4):1491–1514, doi:10.5194/wcd-6-1491-2025

Kumar, A., Mandal, J., Mehrdad, S., and Jacobi, C. , 2025: A novel approach to predict the arctic stratospheric ozone from stratospheric polar vortex dynamics using explainable machine learning. Sci. Rep., doi:10.1038/s41598-025-24379-9

2024

Mehrdad, S., Handorf, D., Höschel, I., Karami, K., Quaas, J., Dipu, S., and Jacobi, C. , October 2024: Arctic Climate Response to European Radiative Forcing: A Deep Learning Study on Circulation Pattern Changes. Weather Clim. Dyn., 5(4):1223–1268, doi:10.5194/wcd-5-1223-2024

Kuchar, A., Öhlert, M., Eichinger, R., and Jacobi, C. , July 2024: Large-Ensemble Assessment of the Arctic Stratospheric Polar Vortex Morphology and Disruptions. Weather Clim. Dyn., 5(3):895–912, doi:10.5194/wcd-5-895-2024

2023

Köhler, R. H., Jaiser, R., and Handorf, D. , December 2023: How Do Different Pathways Connect the Stratospheric Polar Vortex to Its Tropospheric Precursors? Weather Clim. Dyn., 4(4):1071–1086, doi:10.5194/wcd-4-1071-2023

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

Jaiser, R., Akperov, M., Timazhev, A., Romanowsky, E., Handorf, D., and Mokhov, I. , September 2023: Linkages between Arctic and Mid-Latitude Weather and Climate: Unraveling the Impact of Changing Sea Ice and Sea Surface Temperatures during Winter. Meteorol. Z., 32(3):173–194, doi:10.1127/metz/2023/1154

Galytska, E., Weigel, K., Handorf, D., Jaiser, R., Köhler, R., Runge, J., and Eyring, V. , September 2023: Evaluating Causal Arctic-Midlatitude Teleconnections in CMIP6. J. Geophys. Res. Atmospheres, 128(17):e2022JD037978, doi:10.1029/2022JD037978

Riebold, J., Richling, A., Ulbrich, U., Rust, H., Semmler, T., and Handorf, D. , July 2023: On the Linkage between Future Arctic Sea Ice Retreat, Euro-Atlantic Circulation Regimes and Temperature Extremes over Europe. Weather Clim. Dyn., 4(3):663–682, doi:10.5194/wcd-4-663-2023

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., 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

Karami, K., Borchert, S., Eichinger, R., Jacobi, C., Kuchar, A., Mehrdad, S., Pisoft, P., and Sacha, P. , April 2023: The Climatology of Elevated Stratopause Events in the UA-ICON Model and the Contribution of Gravity Waves. J. Geophys. Res. Atmospheres, 128(7):e2022JD037907, doi:10.1029/2022JD037907

Karami, K., Garcia, R., Jacobi, C., Richter, J. H., and Tilmes, S. , March 2023: The Holton–Tan Mechanism under Stratospheric Aerosol Intervention. Atmospheric Chem. Phys., 23(6):3799–3818, doi:10.5194/acp-23-3799-2023

2022

Karami, K., Mehrdad, S., and Jacobi, C. , December 2022: Response of the Resolved Planetary Wave Activity and Amplitude to Turned off Gravity Waves in the UA-ICON General Circulation Model. J. Atmospheric Sol.-Terr. Phys., 241:105967, doi:10.1016/j.jastp.2022.105967

Schneider, T., Lüpkes, C., Dorn, W., Chechin, D., Handorf, D., Khosravi, S., Gryanik, V. M., Makhotina, I., and Rinke, A. , January 2022: Sensitivity to Changes in the Surface-layer Turbulence Parameterization for Stable Conditions in Winter: A Case Study with a Regional Climate Model over the Arctic. Atmospheric Sci. Lett., 23(1):e1066, doi:10.1002/asl.1066

2021

Rinke, A., Cassano, J. J., Cassano, E. N., Jaiser, R., and Handorf, D. , July 2021: Meteorological Conditions during the MOSAiC Expedition. Elem. Sci. Anthr., 9(1):00023, doi:10.1525/elementa.2021.00023

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

Köhler, R., Handorf, D., Jaiser, R., Dethloff, K., Zängl, G., Majewski, D., and Rex, M. , March 2021: Improved Circulation in the Northern Hemisphere by Adjusting Gravity Wave Drag Parameterizations in Seasonal Experiments With ICON-NWP. Earth Space Sci., 8(3):e2021EA001676, doi:10.1029/2021EA001676

2020

Mewes, D. and Jacobi, C. , March 2020: Horizontal Temperature Fluxes in the Arctic in CMIP5 Model Results Analyzed with Self-Organizing Maps. Atmosphere, 11(3):251, doi:10.3390/atmos11030251

Vihma, T., Graversen, R., Chen, L., Handorf, D., Skific, N., Francis, J. A., Tyrrell, N., Hall, R., Hanna, E., Uotila, P., Dethloff, K., Karpechko, A. Y., Björnsson, H., and Overland, J. E. , January 2020: Effects of the Tropospheric Large-scale Circulation on European Winter Temperatures during the Period of Amplified Arctic Warming. Int. J. Climatol., 40(1):509–529, doi:10.1002/joc.6225

2019

Dethloff, K., Handorf, D., Jaiser, R., and Rinke, A. , November 2019: Kältere Winter durch abnehmendes arktisches Meereis: Klima- und Zirkulationsänderungen in der Arktis. Phys. Unserer Zeit, 50(6):290–297, doi:10.1002/piuz.201901547

Rinke, A., Knudsen, E. M., Mewes, D., Dorn, W., Handorf, D., Dethloff, K., and Moore, J. C. , June 2019: Arctic Summer Sea Ice Melt and Related Atmospheric Conditions in Coupled Regional Climate Model Simulations and Observations. J. Geophys. Res. Atmospheres, 124(12):6027–6039, doi:10.1029/2018JD030207

Romanowsky, E., Handorf, D., Jaiser, R., Wohltmann, I., Dorn, W., Ukita, J., Cohen, J., Dethloff, K., and Rex, M. , May 2019: The Role of Stratospheric Ozone for Arctic-midlatitude Linkages. Sci. Rep., 9(1):7962, doi:10.1038/s41598-019-43823-1

Mewes, D. and Jacobi, C. , March 2019: Heat Transport Pathways into the Arctic and Their Connections to Surface Air Temperatures. Atmospheric Chem. Phys., 19(6):3927–3937, doi:10.5194/acp-19-3927-2019

Dethloff, K., Handorf, D., Jaiser, R., Rinke, A., and Klinghammer, P. , January 2019: Dynamical Mechanisms of Arctic Amplification. Ann. N. Y. Acad. Sci., 1436(1):184–194, doi:10.1111/nyas.13698

2018

Kreyling, D., Wohltmann, I., Lehmann, R., and Rex, M. , March 2018: The Extrapolar SWIFT Model (Version 1.0): Fast Stratospheric Ozone Chemistry for Global Climate Models. Geosci. Model Dev., 11(2):753–769, doi:10.5194/gmd-11-753-2018

2017

Jacobi, C., Ermakova, T., Mewes, D., and Pogoreltsev, A. I. , September 2017: El Niño Influence on the Mesosphere/Lower Thermosphere Circulation at Midlatitudes as Seen by a VHF Meteor Radar at Collm (51.3 \textasciicircum \circ N, 13 \textasciicircum \circ E). Adv. Radio Sci., 15:199–206, doi:10.5194/ars-15-199-2017

Stober, G., Matthias, V., Jacobi, C., Wilhelm, S., Höffner, J., and Chau, J. L. , June 2017: Exceptionally Strong Summer-like Zonal Wind Reversal in the Upper Mesosphere during Winter 2015/16. Ann. Geophys., 35(3):711–720, doi:10.5194/angeo-35-711-2017

Wendisch, M., Brückner, M., Burrows, J., Crewell, S., Dethloff, K., Ebell, K., Lüpkes, C., Macke, A., Notholt, J., Quaas, J., Rinke, A., and Tegen, I. , January 2017: Understanding Causes and Effects of Rapid Warming in the Arctic. Eos, doi:10.1029/2017EO064803

2016