Ocean in the Earth System: Waves by Christian Klepp

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.  Öffnet ein Fenster zum Versenden einer E-Mailemail

Max Popp is investigating dynamics of a runaway greenhouse climate, with emphasis on the influence of clouds on the onset of runaway positive feedback.   Öffnet ein Fenster zum Versenden einer E-Mailemail


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. Öffnet ein Fenster zum Versenden einer E-Mailemail


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.

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.  Öffnet ein Fenster zum Versenden einer E-Mailemail


Davide Zanchettin is interested in multidecadal to centennial climate variability.  He is now using the externer Link folgtCOSMOS "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.  Öffnet ein Fenster zum Versenden einer E-Mailemail



Variability and 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.


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.   Öffnet ein Fenster zum Versenden einer E-Mailemail


Daniela Matei is using the ECHAM6/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.  Opens window for sending emailemail

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.

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.  Öffnet ein Fenster zum Versenden einer E-Mailemail

Luis KornbluehÖffnet ein Fenster zum Versenden einer E-Mailemail


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.  Öffnet ein Fenster zum Versenden einer E-Mailemail


Uwe SchulzweidaÖffnet ein Fenster zum Versenden einer E-Mailemail


Previous Group Members

Jaison Thomas Ambadan

externer Link folgtJurgen Bader

Opens external link in current windowJohanna Baehr (now at the Opens external link in current windowInstitute of Oceanography, Hamburg)

Astrid Baquero

Werner Bauer

Oliver Bothe

Michael Botzet (now at Decadal Climate Predictions group)

  Jörn Callies

Opens external link in current windowMaria Paz Chidichimo

Deike Kleberg (now at Decadal Climate Predictions group)

externer Link folgtClotilde Dubois

Nils Fischer

Opens external link in current windowAlmut Gaßmann

Heiko Hansen

Malte Heineman

Chie Ihara

Ketan Kulkarn (now at Decadal Climate Predictions group)

Mario Krapp

externer Link folgtFelix Landerer

Fiona McLay

Modali Kameswarrao (now at Decadal Climate Predictions group)

Wolfgang Müller (now at Decadal Climate Predictions group)

Lin Mu

Ismael Núñez-Riboni

Ronny Petrik

Holger Pohlmann (now at Decadal Climate Predictions group)

Marco Restelli

Stefanie Rohrer

Frank Sienz (now at Decadal Climate Predictions group)

externer Link folgtRobin Smith

Zoltan Szuts

Steffen Tietsche

Aiko Voigt (now in the Atmosphere in the Earth System department)

Nina Wilkens

externer Link folgtXiuhua Zhu