Impact of terrestrial hydrology on L-A feedbacks and isotope signatures

• Applicant: Professor Dr. Harald Kunstmann
• Subject Area: Hydrogeology, Hydrology, Limnology, Urban Water Management, Water Chemistry, Integrated Water Resources Management ; Atmospheric Science
• Term: since 2024
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 514721519

L-A feedbacks depend on the exchange of water between the land and the atmosphere and more generally on L-A water pathways. A sound understanding of the processes related to L-A water pathways requires a joint measuring-modeling effort and the consideration of a great variety of both terrestrial and atmospheric variables, as they are offered by the LAFO observatory and LAFI. We will particularly consider stable water isotopologues and focus on the role of terrestrial hydrological processes on L-A feedbacks. The research objective of P9 is to improve our understanding of the relationship and interactions between groundwater, soil moisture in the unsaturated zone, ET partitioning, isotope signatures and L-A feedbacks, in the framework of LAFI objectives 2, 3, 4, E and S. The research hypotheses of P9 are that the consideration of isotopes in a L-A system model allows to better constrain the partitioning between E and T, reduce systematic errors in simulated ET, and more accurately characterize L-A coupling strength. Our studies will be performed with the isotope-enabled version of the fully coupled atmospheric-hydrological modeling system WRF-NoahMP-Gecros-Hydro-iso at turbulence permitting scales, which will allow to represent the isotopic fractionation processes associated with E and T at a relevant scale for comparison to in-situ isotope observation. The collaboration with P1, P4, P5, P6, P7 and P8 under the supervision of PS will allow to share expertise with LAFO datasets and feedback measures. P2 will provide remote sensing information to better constrain the model parameters related to plant transpiration. P3 will provide isotope observations in the land-vegetation-atmosphere system that will be crucial to evaluate and improve WRF-NoahMP-Gecros-Hydro-iso in terms of E – T partitioning. We will benefit from the work done in P4 and P7 to correctly use the Gecros crop modeling option in WRF-NoahMP-Gecros-Hydro-iso, and our modeled isotope results will feed back to the E – T partitioning analysis of P3 and P4. P9 will deliver model data to P10 as part of CCWG-DL. Our analysis of modeled L-A feedbacks with WRF-NoahMP-Gecros-Hydro-iso will be part of CCWG-MME.

• DFG Programme: Research Units
• Subproject of: FOR 5639: Land-Atmosphere Feedback Initiative (LAFI)
• Co-Investigator: Dr. Joel Arnault, Ph.D.