D01: Large-scale dynamical mechanisms of Arctic amplification
Arctic amplification does not depend on local feedback processes in the Arctic only, but is also largely a function of remote large–scale atmospheric dynamical mechanisms. The related horizontal atmospheric energy transports into the Arctic change over time due to internally generated and externally forced changes in large–scale atmospheric and oceanic variability patterns. In D01 we will study, whether the horizontal moist static energy (MSE) transports in the atmosphere are impacted by (a) the oceanatmosphere variability and background state, (b) the changing geographical patterns of climate radiative forcing, and (c) the stratospheric variability, which is largely determined by planetary and gravity wave (GW) driven dynamics and the feedback processes between stratospheric dynamics and chemistry. To investigate the relative role of the processes (a), (b), and (c) we will perform a series of ICOsahedra Non-hydrostatic model (ICON) model experiments with (i) prescribed idealised sea ice and oceanic boundary conditions, (ii) idealised changes in mid-latitude radiative forcing patterns, and (iii) modifications of stratospheric GW patterns. To study the impact of the interactive stratospheric ozone chemistry, we complement our simulations with ICON runs including the fast interactive ozone module SWIFT (Semi-empirical Weighted Iterative Fit Technique), which enables mutual interactions between the ozone layer and climate in the global model ICON. Our model results, together with reanalyses and CMIP6 results, will be analysed with respect to (i) MSE transport patterns and large–scale circulation regimes using advanced cluster analyses (e.g., selforganising maps, SOM) to determine current and future trends and changes of atmospheric transport and circulation patterns, and (ii) dynamical mechanisms of Arctic–mid–latitude linkages impacting the detected changes in MSE transport patterns. Special emphasis will be put on the effects of troposphere-stratosphere coupling and low–latitude GW hotspots on the polar vortex dynamics. The modelling results will be compared to observations from the HALO-(AC)³ campaign and satellite retrievals.
Atmospheric energy transports critically depend on the ocean-atmosphere background state, changing patterns of climate forcing and stratospheric variability
Specifically we want to answer the following questions:
- How much are the changes in horizontal MSE transports impacted by the ocean-atmosphere background state, changing patterns of climate forcing and stratopheric variability?
- What are the dynamical mechanisms of Arctic-mid-latitude linkages underlying the trends and changes of the horizontal MSE transports?
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
Dr. Markus Rex
Alfred-Wegener-Institute Helmholtz Center for Polar and Marine Research
Prof. Dr. Johannes Quaas
University of Leipzig
Leipzig Institute for Meteorology (LIM)
Prof. Dr. Christoph Jacobi
University of Leipzig
Leipzig Institute for Meteorology (LIM)
Alfred Wegener Institute
D. Mewes and C. Jacobi, 2020: Horizontal Temperature Fluxes in the Arctic in CMIP5 Model Results Analyzed with Self-Organizing Maps, Atmosphere, vol. 11, no. 3, doi: 10.3390/atmos11030251.
Rinke, A., E. Knudsen, D. Mewes, W. Dorn, D. Handorf, K. Dethloff, J.C. Moore, 2019: Arctic summer sea-ice melt and related atmospheric conditions in coupled regional climate model simulations, J. Geophys. Res., 124, doi:10.1029/2018JD030207
Romanowsky, E., D. Handorf, M. Rex, R. Jaiser, I. Wohltmann, W. Dorn, J. Ukita, J. Cohen, and K. Dethloff, 2019: The role of stratospheric ozone for Arctic-midlatitude linkages, Nature Scientific Reports, 9, Article 7962, doi:10.1038/s41598-019-43823-1
Mewes, D., and C. Jacobi, 2019: Heat Transport Pathways into the Arctic and their Connections to Surface Air Temperatures, Atmos. Chem. Phys., 19, 3927-3937, doi:10.5194/acp-19-3927-2019
Dethloff, K., D. Handorf, R. Jaiser, A. Rinke, P. Klinghammer, 2019: Dynamical mechanisms of Arctic amplification, Annals of New York Academy of Sciences, 1436, doi:10.1111/nyas.13698
Kreyling, D., Wohltmann, I., Lehmann, R., and Rex, M., 2018: The Extrapolar SWIFT model (version 1.0): Fast stratospheric ozone chemistry for global climate models, Geosci. Model Dev., 11, 753-769, doi:10.5194/gmd-11-753-2018
Jacobi, Ch., T. Ermakova, D. Mewes, and A.I. Pogoreltsev, 2017: El Niño influence on the mesosphere/lower thermosphere circulation at midlatitudes as seen by a VHF meteor radar at Collm (51.3°N, 13°E), Adv. Radio Sci., 15, 199-206, doi:10.5194/ars-15-199-2017
Stober, G., Matthias V. , Jacobi Ch., Wilhelm S., Höffner J., Chau J.L., 2017: Exceptionally strong summer-like zonal wind reversal in the upper mesosphere during winter 2015/16, Ann. Geophys., 35, 711-720, doi:10.5194/angeo-35-711-201
Wendisch, M., M. Brückner, J. P. Burrows, S. Crewell, K. Dethloff, K. Ebell, Ch. Lüpkes, A. Macke, J. Notholt, J. Quaas, A. Rinke, and I. Tegen, 2017: Understanding causes and effects of rapid warming in the Arctic. Eos, 98, doi:10.1029/2017EO064803