Seminar: Xu Shan
Institutsseminar
- Date: Apr 16, 2026
- Time: 02:00 PM (Local Time Germany)
- Speaker: Xu Shan
- (Reichstein department)
How Plant Hydraulic Scheme Constrains Carbon Turnover Processes in Terrestrial Biosphere Model: model-data integration experiments using Earth Observation and FLUXNET measurements
An improved representation of the carbon and water cycle dynamics in terrestrial ecosystems underpins a large uncertainty reduction in modeling Earth system dynamics. The climate sensitivity of ecosystem processes controls land-atmosphere interactions and the overall atmospheric carbon uptake and release dynamics across scales. Local and Earth observations of vegetation dynamics are key for the evaluation of our understanding and support the quantification of process representation in model development.
Long-wavelength radar backscatter provides unique insights into the dynamics of plant water and carbon dynamics when compared to optical EO products, as such, embeds the potential for constraining various parameters controlling local climate vegetation responses. In this study, we present an approach for assimilating L-band ALOS PALSAR backscatter data and MODIS optical data along with carbon and water fluxes measured at FLUXNET sites into a terrestrial ecosystem model to improve estimates of vegetation parameters of turnover rates. A semi-empirical radiative transfer model is employed as the observation operator linking modeled plant water content to L-band backscatter. Multiple model–data integration experiments are conducted to assess the added value of plant hydraulic scheme in terrestrial biosphere model, including configurations with and without plant hydraulic schemes, with and without radar constraints, and across temporal scales ranging from sub-daily to monthly.
Our results indicate that adding plant hydraulic scheme into land carbon/water simulations primarily improves the estimates of carbon and water fluxes. It also reduces the uncertainty of carbon turnover parameters. Assimilating L-band backscatter observations also improves estimates of carbon and water states and fluxes and strengthens constraints on related parameters. However, persistent equifinality between plant water and carbon cycle processes remains. Ultimately, this study highlights the potential of L-band backscatter to enhance vegetation carbon cycle modeling, emphasizes the added value of the newly launched ESA BIOMASS mission, and underscores the importance of integrating vegetation water dynamics into carbon models.
Long-wavelength radar backscatter provides unique insights into the dynamics of plant water and carbon dynamics when compared to optical EO products, as such, embeds the potential for constraining various parameters controlling local climate vegetation responses. In this study, we present an approach for assimilating L-band ALOS PALSAR backscatter data and MODIS optical data along with carbon and water fluxes measured at FLUXNET sites into a terrestrial ecosystem model to improve estimates of vegetation parameters of turnover rates. A semi-empirical radiative transfer model is employed as the observation operator linking modeled plant water content to L-band backscatter. Multiple model–data integration experiments are conducted to assess the added value of plant hydraulic scheme in terrestrial biosphere model, including configurations with and without plant hydraulic schemes, with and without radar constraints, and across temporal scales ranging from sub-daily to monthly.
Our results indicate that adding plant hydraulic scheme into land carbon/water simulations primarily improves the estimates of carbon and water fluxes. It also reduces the uncertainty of carbon turnover parameters. Assimilating L-band backscatter observations also improves estimates of carbon and water states and fluxes and strengthens constraints on related parameters. However, persistent equifinality between plant water and carbon cycle processes remains. Ultimately, this study highlights the potential of L-band backscatter to enhance vegetation carbon cycle modeling, emphasizes the added value of the newly launched ESA BIOMASS mission, and underscores the importance of integrating vegetation water dynamics into carbon models.
(by Xu Shan, Sujan Koirala, Markus Zehner, Ranit De, Lazaro Alonso, Konstantinos Papathanassiou, and Nuno Carvalhais)