EGU General Assembly 2020
© Author(s) 2020. This work is distributed under
the Creative Commons Attribution 4.0 License.

Simulating the seasonal cycle of 13C

Sebastian Lienert1,2, Christoph Köstler3, Sönke Zaehle3, and Fortunat Joos1,2
Sebastian Lienert et al.
  • 1Climate and Environmental Physics, Physics Institute University of Bern, Bern, CH-3012, Switzerland
  • 2Oeschger Centre for Climate Change Research, University of Bern, Bern, CH-3012, Switzerland
  • 3Max Planck Institute for Biogeochemistry, P.O. Box 600164, Hans-Knöll-Str. 10, 07745 Jena, Germany

We investigate the seasonal cycle of δ13CO2 using the Earth system model of intermediate complexity Bern3D-LPX. Using a model of atmospheric transport (TM3), the spatial fields of simulated 13CO2 and CO2 exchange are translated to local δ13CO2 anomalies, which are then compared to atmospheric measurements. We discuss the ability of the model to accurately simulate the atmospheric seasonal δ13CO2 cycle, which could prove to be a valuable novel observational constraint. The coupled simulation allows us to distinguish the relative importance of the biosphere and ocean in determining the seasonal cycle of δ13CO2 at different measurement sites across the world.

The amplitude of the seasonal cycle of δ13CO2 is of particular importance to quantify land biosphere processes. The decreasing δ13CO2 of the atmosphere during the last decades (Suess effect) leads to a divergence of the δ13C signature in assimilation and heterotrophic respiration, because of the long lifetime of soil pools. This is expected to lead to a high sensitivity of the seasonal amplitude to the amount of soil respiration. The effect of changes in soil turnover times on the simulated seasonal cycle is explored with factorial simulations of the Dynamic Global Vegetation Model LPX-Bern.

How to cite: Lienert, S., Köstler, C., Zaehle, S., and Joos, F.: Simulating the seasonal cycle of 13C, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-7841,, 2020

This abstract will not be presented.