Towards ecosystem reanalysis by coupling of water and carbon cycles
Prof. Dr. Harrie-Jan Hendricks-Franssen
Forschungszentrum Jülich | +49 2461 614462 |
Prof. Dr. Wulf Amelung
University of Bonn | +49 228 73-2780 |
Prof. Dr. Jürgen Kusche
University of Bonn | +49 228 73-2629 |
In project C03 we investigate the impact of uncertain ecosystem parameters and the representation of soil respiration in a land surface modelling approach on the simulation of the coupled water, energy and biogeochemical cycles over Eurasia, focusing on the variability of water and carbon fluxes in space and time. This is particularly relevant for simulating the impact of land use and land cover change on these cycles. We will set up an ensemble of land surface models, all with (slightly) different inputs of atmospheric forcings and soil and vegetation parameters, to represent the uncertainty we have in these forcings and parameters. We will investigate which sources of uncertainty are more important and whether the land surface model is able to reproduce the observed values taking into account these sources of uncertainty. Using measurement data from well-equipped sites across Europe (e.g., from the ICOS and eLTER networks), we will modify model parameters so that model simulations better reproduce measured values. At the same time, based on experimental data across Europe, the representation of soil respiration in the model will be improved, in particular the dependence of soil respiration on soil temperature and soil moisture. In addition, an ensemble of land surface model runs over Eurasia will be performed using these updated parameters and the improved representation of the respiration process. We will test whether the implemented changes have improved the performance of the land surface model by using a completely independent data source, the monitoring of continental water storage changes by the GRACE satellite. We hypothesize that the continental-scale net ecosystem exchange (NEE) from a reanalysis with improved ecosystem parameters and improved representation of soil respiration (SR) will be better correlated with observed total water storage (TWS) variability.
Contribution to the CRC
Simulation of the coupled water and carbon cycles paves the way to the CRC’s next phase. Project C03 will work closely with project A01, providing data on soil physical and chemical properties which will be used by A01 and A02. Multidecadal GRACE-like water storage change fields will be of use e.g. for projects D03 and D07, when it comes to analyzing water budgets for the pre-GRACE time frame. Our project will further benefit from collaboration with several projects in cluster C.
To test our hypothesis, we will derive measurements on heterotrophic soil respiration and its dependence on soil moisture and temperature across a European climate-transect and under different land uses. Furthermore, we will estimate ecosystem parameters at highly equipped measurement observation sites (ICOS and LTER) from soil moisture, LAI, and NEE measurements (land surface model CLM5, parameter estimation with Iterative Ensemble Smoother). We will also combine gained knowledge on soil respiration and ecosystem parameters to establish a prototype for ecosystem reanalysis over Eurasia and set up an ensemble of spatially distributed CLM5.0 model simulations. Finally, we will provide a long-term GRACE like TWS data. The reconstruction will be based on data from satellite laser ranging (SLR) available since 1990s and GRACE. Furthermore, we will assess the observed coupling between atmospheric CGR and TWS variability and compare this with the simulated coupling for default (standard CLM5) and estimated ecosystem parameters.
Main results in 2022
- Conducted sampling and measuring campaign of 9 out of 12 sites on a European transect
- Vereecken, H., W. Amelung, S.L. Bauke, M. Bechtold, G. Blöschl, H. Bogena, N., Brüggemann, A. Carminati, M. Javaux, A.G. Konings, J. Kusche, C. Montzka, I. Neuweiler, D. Or, S. Steele-Dunne, A. Verhoef, M. Young, J. Vanderborght, Y. Zhang. 2022. Soil hydrology in the Earth system. Nature Rev Earth Environ. 9: 573-387; https://doi.org/10.1038/s43017-022-00324-6
- Schimmel, H. and W. Amelung (2022): Organic soils. In: Encyclopedia of Soils in the Environment, Second Edition. Reference Module in Earth Systems and Environmental Sciences, Elsevier, https://doi.org/10.1016/B978-0-12-822974-3.00073-2
Main results in 2023
- Finishing soil sampling and measuring campaign on the European transect.
- Conducting ensemble simulations using CLM5.0 at well-equipped European sites to assess the impact of uncertain meteorological data, soil parameters, and vegetation parameters on model outcomes, while also comparing simulations to measurements