JSBACH is the land component of MPI-ESM. As integral part of ECHAM6, it provides the lower atmospheric boundary conditions over land. In addition, in the wider context of the Earth System Model, it adds the biogeochemical and biogeophysical degrees of freedom to the Earth system dynamics that arise from terrestrial processes.
JSBACH has originally been derived by isolating the land components from ECHAM5 (Roeckner et al., 2003), in particular the soil hydrology, the soil heat transport, and the land surface energy balance. To represent the dynamics of land carbon uptake and release, the core system has subsequently been extended by incorporating the photosynthesis and canopy radiation components from the BETHY model (Knorr, 1998), by adding a prognostic phenology scheme, and by developing suitable components for uptake, storage, and release of carbon from vegetation and soils. Natural changes in the geographic extent of landcover is simulated prognostically by a dynamic vegetation module (including wind and fire damage) whereas anthropogenic land cover change is prescribed either by sequences of maps, or by forcing JSBACH with the transition matrices of the New Hampshire Harmonized Protocol developed for CMIP5.
Accessing the JSBACH source code
JSBACH can be run online, i.e. as part of ECHAM6, or offline ("JSBALONE") forced by climate data. The resolution of the online version is determined by the hosting ECHAM6 model, whereas the resolution of the offline version follows the resolution of the climate forcing data. In a third configuration ("CBALONE"), the land carbon cycle and the sub-models for land cover change can be run separately such that, when forced by simulation data from online runs, land cover and carbon can be reproduced to numerical accuracy.
A full documentation is under development. Particular aspects of the model are described in:
Land carbon cycle: Raddatz, T. J., C. H. Reick, W. Knorr, J. Kattge, E. Roeckner, R. Schnur, K.-G. Schnitzler, P. Wetzel and J. Jungclaus: Will the tropical land biosphere dominate the climate - carbon cycle feedback during the twenty-first century?. In: Climate Dynamics 29, 565-574 (2007). doi: 10.1007/s00382-007-0247-8
Land physics and coupling to atmosphere: Roeckner, E., G. Bäuml, L. Bonaventura, R. Brokopf, M. Esch, M. Giorgetta, S. Hagemann, I. Kirchner, L. Kornblueh, E. Manzini, A. Rhodin, U. Schlese, U. Schulzweida, A. Tompkins: The atmospheric general circulation model ECHAM 5. PART I: Model description, MPI Report 349 (2003)
Dynamic albedo scheme: Vamborg, F. S. E., V. Brovkin, and M. Claussen: The effect of a dynamic background albedo scheme on Sahel/Sahara precipitation during the mid-Holocene, Climate of the Past, 7, 117-131 (2011). doi:10.5194/cp-7-117-2011.
Photosynthesis and canopy radiation: Knorr, W.: Satellite Remote Sensing and Modelling of the global CO2 exchange of land vegetation: A synthesis study, Examensarbeiten Nr. 49, MPI for Meteorology (1998)
Land cover change: Reick, C., Raddatz, T., Brovkin, V. & Gayler, V. (2013). Representation of natural and anthropogenic land cover change in MPI-ESM. Journal of Advances in Modeling Earth Systems, 5, 459-482 , doi:10.1002/jame.20022.