The motivation of this joint project is to obtain more accurate predictions of climate and sea level changes, in order to provide political decision-makers and the society as a whole with the best possible expert knowledge as a basis for their actions.

The second project phase builds on the knowledge, results and collaborations that were developed and established during the first phase of GROCE. The overall goals are to improve our understanding of the dynamics of the changing Greenland system, and to quantify the current and future ice mass loss with greater reliability and accuracy.

To achieve these goals, GROCE-2 bundles the excellent expertise of German research institutions in the fields of oceanography, glaciology, geodesy and atmospheric physics, and combines in-situ observations, remote sensing methods, modeling of ocean and glacier dynamics, as well as processes in the atmosphere and the lithosphere over a large range of time scales (intraseasonal to a century) and space scales (few hundred meters to few thousand kilometers).

It is the goal of this subproject 9 to estimate melt rates at the water-ice interface below the 79°N glacier (79NG) by means of idealised and spatially highly resolved model simulations. Since the necessary resolution cannot be achieved in realistic coupled ocean-ice-shield models, physical parameterisations and numerical methods will be developed to be integrated in the coupled model of TP2 (ice-shield-ocean interaction – the future of the 79°N glacier).

The energy transfers between the three dynamical regimes (small-scale turbulence, internal gravity waves and geostrophically balanced motion) are fundamental to the energy cycle of both the atmosphere and the ocean. Nonetheless, they are poorly understood and quanti fied, and their representation in state-of-the-art Earth system models is unsatisfactory. Since the interactions of the dynamical regimes ultimately link the smallest scales to the largest scales by a variety of complex processes, understanding these interactions is mandatory to construct atmosphere and ocean models and to predict climate. The current lack of understanding is refl ected by energetically inconsistent models with relatively large biases, but also paralleled by inconsistencies of a numerical and mathematical nature. We believe that it is now time to combine recent e fforts to overcome these de ficiencies, to foster new activities to understand the dynamical interactions, and to improve the consistency of ocean and atmosphere models. Through the knowledge gained in the CRC, we hope to reduce the biases and to increase the skill of atmosphere and ocean models, and ultimately to improve climate models and climate predictions. The main aims of this CRC are
i) to develop the necessary understanding of the energy transfers between the di fferent dynamical regimes of the atmosphere and the ocean,
ii) to develop, test and implement with this understanding new and consistent parameterisations in models, and
iii) to develop numerical methods featuring consistent energetics.
It is our vision to subsequently establish an energetically consistent framework of energy conversions in the climate system, and to develop physically, mathematically and numerically consistent models for both the atmosphere and the ocean.