D01: Large-scale dynamical impacts on regional Arctic climate change
PIs: Christoph Jacobi, Johannes Quaas, Markus Rex
We shall investigate the interaction between the variable large–scale circulation and Arctic regional climate patterns. We will diagnose the degree of Arctic Amplification on regional scales in response to large–scale dynamics and its past and projected changes. The central question is to what degree regional Arctic climate change and Arctic Amplification is modulated by changes in large scale horizontal heat fluxes, planetary wave–mean flow interactions, in particular during sudden stratospheric warming events, and generally tropospheric and stratospheric circulation patterns, expressed in terms of the variability of Northern hemisphere circulation variability, e.g., of the NAO (North Atlantic Oscillation) and the NAM (Northern Annual Mode). This includes potential linkages to stratospheric ozone, and the question which part of Arctic Amplification is generated by stratosphere–troposphere exchange. Meteorological reanalyses as well as climate model simulation results, such as available in the Coupled Model Intercomparison Project Phase 5 (CMIP5) multi–model ensemble, together with additional climate model runs with the ICON model, conducted in the project, will be used. The variability of large scale heat fluxes, planetary waves, and dynamical patterns like NAO and NAM will be analysed statistically in connection with regional Arctic tropospheric and surface parameters focusing on temperatures and sea ice extent. The final result will be a quantitative analysis of the:
- Role of horizontally and vertically coupled large–scale circulation changes on regional patterns of Arctic climate change and Arctic Amplification,
- Relative importance of changes in the large–scale circulation and of local feedback processes on Arctic Amplification, regionally resolved in the Arctic, and
- Role of troposphere/stratosphere coupling for Arctic Amplification, including the role of stratospheric ozone variability.
This will provide a tool to interpret observed regional climate change and to distinguish between the effects of changes in the large–scale circulation and those of regional physical processes responsible for Arctic Amplification.
Regionally dependent large–scale and local feedback effects are expected to be of different strength, and the question is, where local feedback effects are observed most strongly.
Hypothesis: Regional Arctic climate change and Arctic Amplification is modulated by largescale tropospheric and stratospheric circulation patterns.
Role within (AC)³
- Define regions most sensitive to local feedback processes in cooperation with Cluster A
- Assist interpreting observations in collaboration with B06, E02, E03
- Provide large-scale analyses as boundary values for regional modelling in B05, D02, D03 and E04
- Analyse in-situ processes with D02 and D03 and use their results in WP3
- Physical feedback mechanisms analysis in E01
- NAM and NAO analyses with B01 and E01
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