TRR 172:  ArctiC Amplification: Climate Relevant Atmospheric and SurfaCe Processes, and Feedback Mechanisms (AC)3

• Subject Area: Geosciences
• Term: since 2016
• Website: Homepage
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 268020496

Planet earth has warmed on average by 0.87 K over the past 150 years. In the Arctic, the warming is much larger, which became most prominent over the last decades. Currently, the Arctic warming exceeds the increase of near-surface air temperature in the mid-latitudes by about 2 K. This phenomenon is commonly referred to as Arctic amplification. The excessive Arctic warming, which is predicted to progress during the 21st century, is both a consequence and a driver of feedback processes specific to the Arctic. These interlinked mechanisms cause further dramatic and alarming changes, such as the stronger-than-expected decline of the Arctic sea ice. The feedback processes are related in part to the unique Arctic conditions such as the pronounced temperature inversions close to the ground, heterogeneous surface conditions (open ocean, sea ice), and persisting low-level clouds (often mixed–phase). Additional feedback processes result from atmospheric and oceanic transport and exchange of heat, humidity, and momentum between the ocean currents and the tropospheric and stratospheric circulation. In addition to physical feedback processes, biogeochemical mechanisms involving atmospheric chemistry and the oceanic biosphere impact on the oxidising capacity of the atmospheric boundary layer and free troposphere, as well as on algae and phytoplankton production in the oceanic surface layers. The overarching goals for phase III are to identify, investigate, and evaluate the key processes contributing to Arctic amplification, to improve the understanding of the local and remote feedback mechanisms, and to quantify their relative importance for Arctic amplification. Four cross-cutting activities (CCAs) will be implemented to qualitatively elevate our research to a new, highly integrative level.

• DFG Programme: CRC/Transregios

Current projects

• A01 - Aerosol, clouds, and radiation characteristics from observations and Big Data analysis (Project Heads Macke, Andreas ;  Neggers, Roel )
• A02 - Balloon-borne observations and dedicated simulations of the transitions between typical states of the Arctic atmospheric boundary layer (Project Heads Siebert, Holger ;  Wendisch, Manfred )
• A03 - Impact of low-level clouds and surface conditions on Arctic atmospheric boundary layer turbulence and radiation (Project Heads Handorf, Dörthe ;  Herber, Andreas ;  Lüpkes, Christof ;  Schäfer, Michael ;  Wendisch, Manfred )
• B01 - Changes of the top–of–atmosphere reflectance, brightness temperatures, and cloud properties in the Arctic from 1995 to the present derived from satellite data (Project Heads Burrows, John Philip ;  Vountas, Ph.D., Marco )
• B02 - Remote sensing of aerosols and their properties in the Arctic from satellite observations (Project Heads Burrows, John Philip ;  Bösch, Hartmut ;  Vountas, Ph.D., Marco )
• B03 - Transformation of Arctic mixed–phase clouds in cold air outbreaks characterized by airborne and satellite remote sensing (Project Heads Crewell, Susanne ;  Deneke, Hartwig ;  Ehrlich, André ;  Macke, Andreas )
• B04 - Spatial distribution, sources, and cloud processing of aerosol particles (Project Heads Herber, Andreas ;  Herrmann, Hartmut ;  van Pinxteren, Manuela ;  Pöhlker, Mira ;  Stratmann, Frank )
• B05 - Variability and trends of water vapor in the Arctic (Project Heads Crewell, Susanne ;  Ebell, Kerstin ;  Heygster, Georg ;  Rinke, Annette ;  Spreen, Gunnar )
• C01 - ffects of heterogeneous sea ice properties on radiative energy fluxes and its influence on Arctic amplification (Project Heads Heygster, Georg ;  Jäkel, Evelyn ;  Nicolaus, Marcel ;  Spreen, Gunnar ;  Wendisch, Manfred )
• C03 - Atmospheric composition and ocean color feedback to Arctic amplification (Project Heads Blechschmidt, Anne-Marlene ;  Bracher, Astrid ;  Burrows, John Philip ;  Richter, Andreas )
• C04 - Coupling between atmosphere, mixed layer and pycnocline under Arctic amplification: the role of sea ice related processes (Project Heads Kanzow, Ph.D., Torsten ;  Rhein, Monika ;  Walter, Maren )
• D01 - Large-scale dynamical mechanisms of Arctic–mid-latitude linkages (Project Heads Handorf, Dörthe ;  Jacobi, Christoph ;  Quaas, Johannes ;  Rex, Markus )
• D02 - Trends, patterns, and climate effects of aerosol in the Arctic (Project Heads Heinold, Bernd ;  Kretzschmar, Jan ;  Quaas, Johannes ;  Tegen, Ina )
• D03 - Interactions between atmosphere and sea ice-ocean in the Arctic (Project Heads Rinke, Annette ;  Spreen, Gunnar )
• D04 - Interaction of meridional ocean heat transports and regional processes in the Arctic Ocean (Project Heads Gerdes, Rüdiger ;  Kanzow, Ph.D., Torsten ;  Salzmann, Marc )
• D06 - Causal pathways of Arctic-midlatitude interactions (Project Head Kretschmer, Marlene )
• E01 - The role of atmospheric convection in Arctic feedbacks (Project Heads Neggers, Roel ;  Quaas, Johannes )
• E02 - Ny-Ålesund column thermodynamic structure, clouds, aerosols, trace gases and radiative effects (Project Heads Dahlke, Sandro ;  Ebell, Kerstin ;  Maturilli, Marion ;  Notholt, Justus )
• E03 - Process-level assessments of Arctic mixed-phase clouds (Project Heads Kneifel, Stefan ;  Löhnert, Ulrich ;  Neggers, Roel ;  Schemann, Vera ;  Schnitt, Sabrina ;  Shao, Yaping )
• E04 - Moisture intrusions: Processes and climatological impacts (Project Heads Crewell, Susanne ;  Rinke, Annette ;  Spreen, Gunnar )
• E05 - Process-level Understanding of Sublimation and Evaporation of Precipitation (Project Heads Kalesse-Los, Heike ;  Maahn, Maximilian )
• E06 - Diagnosing moisture sources, transport and transformation with water vapor isotopes from satellites and in atmospheric modeling (Project Heads Bösch, Hartmut ;  Quaas, Johannes )
• INFZ03 - Research data management (Project Heads Buschmann, Matthias ;  Notholt, Justus )
• MGKZ02 - Integrated Research Training Group (Project Heads Crewell, Susanne ;  Notholt, Justus ;  Spreen, Gunnar ;  Wendisch, Manfred )
• Z01 - Central services, administration and coordination (Project Heads Crewell, Susanne ;  Notholt, Justus ;  Wendisch, Manfred )
• Z04 - Modeling infrastructure (Project Heads Handorf, Dörthe ;  Quaas, Johannes ;  Schemann, Vera )

Completed projects

• B06 - Latitudinal variability of water vapour, aerosols, and optically thin clouds (Project Heads Neuber, Roland ;  Notholt, Justus )
• B07 - Inluence of sea ice leads or polynyas on Arctic cloud properties (Project Head Kalesse-Los, Heike )
• B08 - Characterising the spatial variability of ice water content in and below mixed-phase clouds (Project Head Maahn, Maximilian )
• C02 - Interactions of snow on sea ice with atmospheric constituents including black carbon (Project Heads Ehrlich, André ;  Gerdes, Rüdiger )

• Applicant Institution: Universität Leipzig
• Co-Applicant Institution: Universität Bremen; Universität zu Köln
• Participating Institution: Alfred-Wegener-Institut; Helmholtz-Zentrum für Polar- und Meeresforschung; Alfred-Wegener-Institut ; Helmholtz-Zentrum für Polar- und Meeresforschung ; Forschungsstelle Potsdam; Leibniz-Institut für Troposphärenforschung e.V. (TROPOS)
• Spokesperson: Professor Dr. Manfred Wendisch