I am an Assistant Professor in the Department of Natural Resources, Faculty of Geo-information Science and Earth Observation. My research and teaching interests and activities focus on the monitoring of agricultural and forestry landscapes and the estimation and modelling of (bio-)physical and ecological processes. For this I work with a wide range of data such as satellite, UAV/drone and field camera images as well as weather, soil and crop information to create physical, data- and process-based models. I am particularly interested in the impact of weather events and climate change on agriculture and ways to support resilient and sustainable agriculture by gaining information about crops and stress events. This information is generated through the application of hydrological and land-atmosphere models as well as process-based crop models using remote sensing and field time-series data. Based on this, it is of great interest to me to combine the advantages of optical and thermal satellite data with high resolution time series from field cameras or UAVs to provide models that cover larger areas while at the same time provide high accuracy through in-situ data calibration. To support these and a wide range of other research and teaching interests I am working on the establishment of a JECAM site in the vicinity of the University of Twente. This research site will provide detailed agricultural and forestry information for calibration and verification of remotely sensed observations and will create a unique data base for spatial-time series data by measuring weather and soil parameters and provide data by field sensors and repetitive UAV surveys.

Before joining ITC and the University of Twente in 2023, I obtained a BSc degree in Environmental Management at Justus-Liebig University Gießen, a European Double Degree MSc in Environmental Sciences – Soil, Water and Biodiversity (EnvEuro) at University of Hohenheim and University of Natural Resources and Life Sciences Vienna (Boku) and a PhD from Georg-August University Göttingen. My PhD was on the testing and development of methods to calculate evapotranspiration from UAV/drone-recorded images of land surface temperatures in oil palm and forest landscapes in the framework of the EFForTS Collaborative Research Centre. As a Post-Doctoral researcher I worked in the ClimXtreme research network in the CROP project on the impact of compound and extreme weather events on crops at the Center for International Development and Environmental Research (ZEU) at Justus-Liebig University Gießen.


  • Agricultural and Biological Sciences

    • Evapotranspiration
    • Temperature
    • Palm Oil
    • Transpiration
    • Rain Forest
    • Agroforestry
  • Earth and Planetary Sciences

    • Investigation
    • Land Surface Temperature



Combining UAV thermography, point cloud analysis and machine learning for assessing small‐scale evapotranspiration patterns in a tropical rainforestEcohydrology, 17(1), Article e2604, 1-13. Cortés‐Molino, Á., Valdés‐Uribe, A., Ellsäßer, F., Bulusu, M., Ahongshangbam, J., Hendrayanto, Hölscher, D. & Röll, A.https://doi.org/10.1002/eco.2604
Complex canopy structures control tree transpiration: A study based on 3D modelling in a tropical rainforestHydrological processes, 37, Article e15045, 1-14. Röll, A., Kang, T., Hahn, P., Ahongshangbam, J., Ellsäßer, F., Hendrayanto, Sharma, P., Wintz, T. & Hölscher, D.https://doi.org/10.1002/hyp.15045UAV-based thermography reveals spatial and temporal variability of evapotranspiration from a tropical rainforestFrontiers in Forests and Global Change, 6, 1-10. Bulusu, M., Ellsäßer, F., Stiegler, C., Ahongshangbam, J., Marques, I., Hendrayanto, H., Röll, A. & Hölscher, D.https://doi.org/10.3389/ffgc.2023.1232410Compound events in Germany in 2018: drivers and case studies. Xoplaki, E., Ellsäßer, F., Grieger, J., Nissen, K., Pinto, J. G., Augenstein, M., Chen, T.-C., Feldmann, H., Friederichs, P., Gliksman, D., Goulier, L., Haustein, K., Heinke, J., Jach, L., Knutzen, F., Kollet, S., Luterbacher, J., Luther, N., Mohr, S., … Wolf, F.https://doi.org/10.5194/egusphere-2023-1460Tree islands enhance biodiversity and functioning in oil palm landscapesNature, 618, 316-321. Zemp, D. C., Guerrero-Ramirez, N., Brambach, F., Darras, K., Grass, I., Potapov, A., Röll, A., Arimond, I., Ballauff, J., Behling, H., Berkelmann, D., Biagioni, S., Buchori, D., Craven, D., Daniel, R., Gailing, O., Ellsäßer, F., Fardiansah, R., Hennings, N., … Kreft, H.https://doi.org/10.1038/s41586-023-06086-5The extremely hot and dry 2018 summer in central and northern Europe from a multi-faceted weather and climate perspectiveNatural hazards and earth system sciences. Rousi, E., Fink, A. H., Andersen, L. S., Becker, F. N., Beobide-Arsuaga, G., Breil, M., Cozzi, G., Heinke, J., Jach, L., Niermann, D., Petrovic, D., Richling, A., Riebold, J., Steidl, S., Suarez-Gutierrez, L., Tradowsky, J. S., Coumou, D., Düsterhus, A., Ellsäßer, F., … Xoplaki, E.https://doi.org/10.5194/nhess-23-1699-2023
Microclimate and land surface temperature in a biodiversity enriched oil palm plantationForest ecology and management, 497, Article 119480. Donfack, L. S., Röll, A., Ellsäßer, F. J., Ehbrecht, M., Irawan, B., Hölscher, D., Knohl, A., Kreft, H., Siahaan, E. J., Sundawati, L., Stiegler, C. & Zemp, D. C.https://doi.org/10.1016/j.foreco.2021.119480Predicting evapotranspiration from drone-based thermography – a method comparison in a tropical oil palm plantationBiogeosciences, 18(3), 861-872. Ellsäßer, F. J., Stiegler, C., Röll, A., June, T., Hendrayanto, H., Knohl, A. & Hölscher, D.https://doi.org/10.5194/bg-18-861-2021Dataset on microclimate and drone-based thermal patterns within an oil palm agroforestry systemData in brief, 39, Article 107615. Donfack, L. S., Röll, A., Ellsäßer, F., Ehbrecht, M., Irawan, B., Hölscher, D., Knohl, A., Kreft, H., Siahaan, E. J., Sundawati, L., Stiegler, C. & Zemp, C. D.https://doi.org/10.1016/j.dib.2021.107615

Research profiles

Courses academic year 2023/2024

Courses in the current academic year are added at the moment they are finalised in the Osiris system. Therefore it is possible that the list is not yet complete for the whole academic year.

Courses academic year 2022/2023


University of Twente

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