Director's Research Group

The OES Director’s Research Group, which is led by Jochem Marotzke and Johann Jungclaus, investigates the dynamics and climate impacts of large-scale ocean variability. We use ocean and Earth system models (ESM) and increasingly incorporate the ICON model as a standard research tool. We combine ocean observations and numerical modelling, exploring existing data sets.


Research activities can be divided into five broad areas:

  • near-term climate prediction

  • past, present and future climate variability

  • conceptual studies of climate dynamics

  • joint analyses of simulations and observational data

  • model development and support

    Simulated and observed 15-year trends of globally averaged surface temperature since 1900. The colour shading indicates how frequently a particular simulated temperature trend occurs as a function of the start year, based on the available 114 simulations. The trends are sorted in classes of 0.025 °C per decade. The circles mark the observed temperature trends.

Near-term climate predictions

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. The projects anchored in the Director’s group cooperate closely with the Decadal Climate Prediction (MiKliP) working group, but focus more on oceanic aspects.


Contacts: Jochem Marotzke, Johann Jungclaus, Daniela Matei, Katja Lohmann, and Ralf Hand




Past, Present, and Future Climate Variability

Many measures of climate exhibit internal variability of various time-scales from days to millennia.   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 centennial to millennial 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. Investigating the response to (mainly) natural forcing under climatic background conditions different from today is crucial for an improved understanding of variability and regional connectivity.


Contacts: Johann Jungclaus, Jochem Marotzke, Ralf Hand, Sebastian Milinski, Christopher Hedemann, Laura Suarez-Gutierrez, Roberta D'Agostino


Projects: MiKlip, PMIP, PACMEDY


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 such as aqua-planets, from reduced complexity models with changing CO2 concentrations, or from theoretical analysis of planetary waves in the ocean.  The main focus is on changes in the ocean circulation due to changed boundary conditions.

Contacts: Jochem Marotzke, Chao Li, Josiane Salameh


Joint analyses of simulations and observational data

We continue our involvement in projects that combine ocean observations and numerical modelling. We focus on process understanding, model evaluation, and assessment of integrated measures of climate change such as heat content variations. We explore the unique RAPID/MOCHA hydrographic dataset and observations from key ocean sites, such as the Greenland-Scotland Ridge, as obtained in the EU NACLIM and BMBF RACE projects. We make use of the growing data set provided by the ARGO program and carbonate system measurements from the SOCAT and GLODAP initiatives.


Contacs: Jochem Marotzke, Johann Jungclaus, Peter Landschützer, Katja Lohmann




Model Development and Support

The OES director’s group participates in the development of the ICON-O ocean model and the Earth System Model ICON-ESM with the goal of establishing the new-generation model ICON-ESM as the standard research tool at the MPI-M. We contribute to the further development through improved parameterizations in collaboration with the Numerical Model Development Group and the Theoretical Oceanography department of Hamburg University. For integrated projects such as CMIP6 we contribute to the definition, test, and application of model set-ups and to the analyses of experiments.


Contacts: Johann Jungclaus, Oliver Gutjahr, Nils Brueggemann, Helmuth Haak, Stephan Lorenz, Michael Botzet