Director's Research Group
Our group, which is led by Jochem Marotzke and Johann Jungclaus, investigates the role of the ocean in the Earth system from diverse perspectives. Most of us use coupled ocean-atmosphere general circulation models to look at large scale climate. Complementary efforts for improving our understanding of the Earth system include improving the physical processes included in the models, improving their numerical accuracy, investigating shorter periods of variability (days to years), and analyzing observational data. The thematic categories below, despite much overlap, broadly summarize how our research fits together.
One of our research topics is the variability of the Atlantic Meridional Overturning Circulation (AMOC) and its impact on climate. The upper right figure shows the AMOC strength (in Sverdrups, 1 Sv = 106 m3 s-1) at 30°N from the 3000-year control run of the Millennium simulations (see the Millenium project). The lower right figure depicts the lagged regression (K Sv-1) between AMOC and 2m air temperature, with AMOC leading by 3 years. All time series were smoothed by a 31-year running mean before regression. The figure demonstrates that Western Europe is strongly influenced by variations in the ocean circulation and heat transports.
Conceptual and Theoretical Climate Dynamics
This theme focuses on the processes and mechanisms that control the state of the climate system – whether from idealized models, from reduced complexity models with changing CO2 concentrations, or from theoretical analysis of planetary waves in the ocean. The main focus is put on changes in the ocean circulation due to changed boundary conditions.
Chao Li is using ECHAM5/MPI-OM to investigate the impact of ocean heat uptake on climate sensitivity. He is also interested in hysteresis behaviour of thermohaline circulation in response to atmospheric CO2 forcing. 
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Max Popp is investigating dynamics of a runaway greenhouse climate, with emphasis on the influence of clouds on the onset of runaway positive feedback. email
Kenji Shimizu (Klaus Hasselmann Fellow) is investigating the roles of oceanic waves in low-frequency (seasonal to decadal) variations of the ocean by using conceptual models and MPI-OM. email
Past, Present, and Future Climate Variability
Although by definition climate applies over long time periods, many measures of climate exhibit internal variability on short periods (weeks to decades) to moderate periods (decadal to centennial). A better understanding of this inherent variability gives insight into what drives changing climate, in addition to defining the limits of how large long-term trends need to be before they stand out from short-term variability. On millenial time scales and longer, Earth's climate has exhibited drastically different states in geological history, and understanding how these climates were maintained is critical for accurately developing climate models that can extrapolate beyond the forcing parameters suitable for current climate.
Oliver Bothe is comparing climate variability between simulations and reconstructions over the past millenium. email
Nils Fischer is simulating past interglacial periods (the Holocene 6,000 years before present, and the Eemian 125,000 yrs before present) using the MPI Earth System Model with a dynamic land surface component. He is especially interested in changes in ocean circulation and changes in variability of large scale climate patterns such as the North Atlantic Oscillation (NAO) and El Niño/Southern Oscillation (ENSO). He is also involved in the analysis of the CMIP5 experiments conducted at the MPI-M. email
Chie Ihara is working on diagnostic analysis of climate model outputs, such as data based on CMIP5, and is interested in climate variability at timescales longer than interannual. email
Johann Jungclaus is interested in climate variability on decadal to multi-centennial time scales. He is coordinating the MPI-M Integrated Project "Simulations of the last Millennium" and is involved in projects on paleo-climatology in the Holocene and the deep past (e.g. Miocene). Particular research interests are: variability of the thermohaline circulation, patterns of climate variability, high latitude climate variability, and decadal predictions. He coordinates the IPCC AR5-related ocean model development and represents the Ocean Department in the MPI-M Coupled Model Steering Group. email
Mario Krapp is investigating the role of ocean gateways in the Middle-Miocene climate (15 million years ago) using a fully coupled general circulation model (
COSMOS). The main focus is put on the changes in the ocean circulation due to changed boundary conditions. email
Katja Lohmann is interested in the North Atlantic Subpolar Gyre and the Atlantic Meridional Overturning Circulation (AMOC), and in particular the mechanisms explaining their variability and their impact on the (ocean) climate in the northern North Atlantic sector using climate model integrations. Current activity includes the sensitivity of the AMOC to deep water formation and overflow changes as well as analysis of the AMOC in the Millennium integrations. email
Zoltan Szuts investigates mooring data across the Atlantic at 26.5°N to understand the signals that combine to form the meridional overturning circulation. As a member of the RAPID project, he also goes to sea to collect and process the data. His interests also include instrumentation, oceanic electric and magnetic fields, internal waves, and meso-scale features. email
Davide Zanchettin is interested in multidecadal to centennial climate variability. He is now using the COSMOS "Community Simulations for the Last Millennium" for investigating the evolution of regional climates and large-scale climate patterns during the last 1200 years. The goal is to gain a deeper understanding of how internal dynamics and external forcings (natural and anthropogenic) contribute to shaping multidecadal to centennial climate variability. email
Decadal Climate Predictability
To what extent are multi-year forecasts of the climate system possible? By starting model simulations with the best-guess of the current state of the ocean and atmosphere, this research theme investigates the accuracy of climate forecasts, both from limitations of the models and from the inherent variability of the climate system.
Michael Botzet is part ot the team that is developing, applying and validating the MPI's Earth system model in various configurations. His current research focus is on climate variability and predictability of the physical climate system using ECHAM5/MPI-OM, including highly idealised model experiments. He is also interested in regionalisation methods and particularly keen on improving our understanding of tropical storms and their possible changes due to anthropogenic climate change. email
Daniela Matei is using the ECHAM5/MPI-OM model to investigate the role of the initial conditions for decadal climate predictions. She is also interested in the impact of global warming on interannual to multidecadal Pacific climate variability. email
Wolfgang Müller is working on the development and assessment of seasonal and decadal climate predictions. email
Holger Pohlmann is working on the development and assessment of decadal climate predictions. email
Steffen Tietsche is studying decadal predictability and variability of Arctic sea ice. He is also interested in sea-ice related tipping point behavior and data assimilation. email
Frank Sienz is working on climate extremes and their variability on time scales ranging from month to years. Currently, he is investigating whether multi-year drought events are predictable with decadal climate prediction systems. 
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Model Development and Support
As most of our research is based on complex coupled models of the ocean, the atmosphere, and even the land, another essential component is making sure that the underlying numerical models are as accurate as possible. Among other topics, we look at discretizing the physical equations, coupling output between ocean/atmosphere/land components, and improving parameterizations of sub-grid-scale processes.
Jaison Thomas Ambadan is developing stochastic parameterization methods to define flow-dependent background errors so that they can be incorporated in a Local Ensemble Transform Kalman Filter (LETKF) data assimilation system. This work is a part of the Quantitative Precipitation Forecast (QPF) project, a joint project between MPI-M, the Deutscher Wetterdienst (DWD), and the Meteorological Institute of the University of Bonn (MIUB). The project aims to build an operational global Ensemble Prediction System (EPS) using the global weather forecast model GME of the Deutscher Wetterdienst. email
Werner Bauer works as a PhD student on discretizing the equations of geophysical fluid dynamics to allow for grid refinement. An application of such a discretization technique will be an R-adaptive shallow water model in the framework of ICON, in which grid points are moved to regions where higher
resolution is required. email
Helmuth Haak is working on numerical ocean modeling. He is maintaining and developing MPI-M's ocean model MPI-OM within the MPI-ESM framework. He is interested in ocean and coupled climate modelling as well as general ocean circulation. email
Deike Kleberg. email
Luis Kornblueh. email
René Redler contributes to the coupled model within the MPI-ESM and ICON framework. He is interested in the development of coupler software targeting Earth system models. Furthermore, he is co-editing a series of books addressing software, tools, standards, and model environments for Earth system modelling. email
Uwe Schulzweida. email
Recent Publications
submitted / under review / in press
Kroeger, J., W. Mueller and J.-S. von Storch: Impact of different ocean reanalyses on decadal climate prediction. In: Climate Dynamics, submitted (2011).
Nunez-Riboni, I., M. Bersch, H. Haak and J. Jungclaus: A multi-decadal meriodional displacement of the subpolar front in the Newfoundland Basin. Ocean Science Discussions 8, 453-482 (2011), under review.
Rayner, D., J. J.-M. Hirschi, T. Kanzow, W. E. Johns, P. G. Wright, E. Frajka-Williams, H. L. Bryden, C. S. Meinen, M. O. Baringer, J. Marotzke, L. M. Beal and S. A. Cunningham: Monitoring the Atlantic meridional overturning circulation. In: Deep-Sea Research Part II: Topical Studies in Oceanography, Online arctice in press (2011).
Saeed, F.; S. Hagemann, S. Saeed, and D. Jacob: Influence of mid-latitude circulation on upper Indus basin precipitation: the explicit role of irrigation. In: Climate Dynamics, submitted (2011).
Szuts, Z.B. : Using motionally-induced electric signals to indirectly measure ocean velocity: instrumental and theoretical developments. In: Progress in Oceanography, in revision (2011).
Szuts, Z.B. and T.B. Sanford : Observations of vertically-averaged velocity in the North Atlantic Current. In: Deep-Sea Research Part II: Topical Studies in Oceanography, in revision (2011).
2011
Akimova, A., U. Schauer, S. Danilov and I. Nunez-Riboni: The role of the deep mixing in the Storfjorden shelf water plume. In: Deep-Sea Research Part I-Oceanographic Research Papers 58, 403-414, (2011). doi: 10.1016/j.dsr.2011.02.001
Bothe, O., K. Fraedrich and X. Zhu: Large-scale circulations and Tibetan Plateau summer drought and wetness in a high-resolution climate model. In: International Journal of Climatology 31, 832-846 (2011). doi: 10.1002/joc.2124
Dallmeyer, A., M. Claussen, U. Herzschuh, and N. Fischer, 2011: Holocene vegetation and biomass changes on the Tibetan Plateau: a model-pollen data comparison. Clim. Past., 7, 881 - 901. 10.5194/cpd-7-1073-2011.
Fischer, N., and J. H. Jungclaus, 2011: Evolution of the seasonal temperature cycle in a transient Holocene simulation: Orbital forcing and sea-ice. Clim. Past Disc., 7, 463 - 483.
Gassmann, A.: Inspection of hexagonal and triangular C-grid discretizations of the shallow water equations. In: Journal of Computational Physics 230, 2706-2721 (2011). doi: 10.1016/j.jcp.2011.01.014
Heinemann, M., A. Timmermann and U. Fendel: Interactions between marine biota and ENSO: a conceptual model analysis. In: Nonlinear Processes 18, 29-40 (2011).
Johns, WE; M.O. Baringer, L.M. Beal, S.A. Cunningham, T. Kanzow, H. L. Bryden, J.J.M. Hirschi, J. Marotzke, C.S. Meinen, B. Shaw, and R. Curry: Continuous, array-based estimates of Atlantic Ocean heat transport at 26.5 degrees N. In: Journal of Climate 24, 2429-2449 (2011). doi: 10.1175/2010JCLI3997.1
Krapp, M. and Jungclaus, J. H., 2011: The Middle Miocene climate as modelled in an atmosphere-ocean-biosphere model, Clim. Past, 7, 1169-1188, doi:10.5194/cp-7-1169-2011.
Park, T., C. J. Jang, J. H. Jungclaus, H. Haak, W. Part and I. Sang Oh: Effects of the Changjiang river discharge on sea surface warming in the Yellow and East China Seas in summer. In: Continental Shelf Research 31, 15-22 (2011). doi: 10.1016/j.csr.2010.10.012
Petrik, R., M. Baldauf, H. Schlünzen, and A. Gassmann: Validation of a mesoscale weather prediction model using sub-domain budgets. In: Tellus A 63(4), 707-726 (2011). doi: 10.1111/j.1600-0870.2011.00528.x 
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Pierrehumbert, R. T., D. S. Abbott, A. Voigt and D. Koll: Climate of the neoproterozoic. In: Annual Review of Earth and Planetary Sciences 39, 417-460 (2011). doi: 10.1146/annurev-earth-040809-152447
Pozzer, A., Jöckel, P., Kern, B., and Haak, H.: The Atmosphere-Ocean General Circulation Model EMAC-MPIOM, Geosci. Model Dev., 4, 771-784, doi:10.5194/gmd-4-771-2011, 2011.
Redler, R., S. Valcke and H. Haak, 2011: The PRISM Support Initiative, COSMOS and OASIS4, In: A. Baklanov, A. Mahura and R. Sokhi (Eds.), Integrated Systems of Meso-Meteorological and Chemical Transport Models, pp. 105-115, Springer Verlag, Berlin, 186 Seiten. url
Saeed, S., Y. Liu and G. Rasul: Multiyear hindcast simulations of summer monsoon over South Asia using a nested regional climate model-BCC_RegCM1.0. In: Theoretical and Applied Climatology, 103, 249-264 (2011). doi: 10.1007/s00704-010-0297-4
Saeed, S., W. A. Mueller, S. Hagemann, D. Jacob, M. Mujumdar and R. Krishnan: Precipitation variability over the South Asian monsoon heat flow and associated teleconnections. In: Geophysical Research Letters 38, Seq. No.: L08702 (2011). doi: 10.1029/2011GL046984
Schmidt, G. A., J. H. Jungclaus, C. M. Ammann, E. Bard, P. Braconnot, T. J. Crowley, G. Delaygue, F. Joos, N. A. Krivova, R. Muscheler, B. L. Otto-Bliesner, J. Pongratz, D. T. Shindell, S. K. Solanki, F. Steinhilber and L. E. A. Vieira: Climate forcing reconstructions for use in PMIP simulations of the last millennium (v1.0). In: Geoscientific Model Development 4, 33-45 (2011). doi: 10.5194/gmd-4-33-2011
Skamarock, W. C., and A. Gassmann, 2011: Conservative transport schemes for spherical geodesic grids: High-order flux operators for ODE-based time integration. Mon. Weather Rev., 139, 2962 - 2975. doi: 10.1175/mwrd-10-05056.1.
Szuts, Z.B., J.R. Blundell, M.P. Chidichimo, and J. Marotzke: A vertical-mode decomposition to investigate low-frequency internal motion across the Atlantic at 26 N. In: Ocean Science Discussion, 8, 2047-2100. 2011. doi:10.5194/osd-8-2047-2011
Tietsche, S., D. Notz, J. H. Jungclaus and J. Marotzke: Recovery mechanisms of Arctic summer sea ice. In: Geophysical Research Letters 38, Art.-No. L02707 (2011). doi: 10.1029/2010GL045698
Voigt, A., D.S. Abbot, R.T. Pierrehumbert and J. Marotzke: Initiation of a marmoun snowball earth in a state-of-the-art atmosphere-ocean general circulation model. In: Climate of the Past, 7, 249-263 (2010) PDF
Voigt, A., Held, I. M., and Marotzke, J. 2011: Hadley cell dynamics in a virtually dry Snowball Earth atmosphere. J. Atmos. Sci, Early Online. doi: 10.1175/JAS-D-11-083.1
Zhu, X., O. Bothe and K. Fraedrich: Summer atmospheric bridging between Europe and East Asia: Influences on drought and wetness on the Tibetan Plateau. In: Quaternary International 236, 151-157 (2011) doi: 10.1016/j.quaint.2010.06.015
Previous Group Members
Johanna Baehr (now at the Institute of Oceanography, Hamburg)
Astrid Baquero
Jörn Callies
Heiko Hansen
Fiona McLay
Lin Mu
Ismael Núñez-Riboni (now in the Ocean Biogeochemistry group)
Stefanie Rohrer
Aiko Voigt (now in the Atmosphere in the Earth System department)
Nina Wilkens