The terrestrial ecosystem plays a major role in studies on the global carbon cycle and on plant production. Not only information on vegetation structure and biochemistry but also on the actual photosynthesis is required for studying vegetation dynamics. Remote sensing has proven to be an important monitoring instrument in this respect.
The reflectance signal has limited capabilities for deriving photosynthesis products. Recent technical sensor developments towards sub-nanometer spectral resolutions offer sun-induced fluorescence (SIF) measurements as an alternative approach for providing complementary information on actual photosynthesis. Therefore, this study focuses on the combined use of SIF and vegetation indices as proxies for studying the dynamics of agricultural systems. However, SIF is a very weak signal that is difficult to separate from the reflectance signal. In order to measure SIF close to the two main emission peaks, the atmospheric oxygen absorption lines O2-B (687 nm) and O2-A (760 nm) will be used. The European Space Agency (ESA) has approved the development and testing of the Fluorescence Explorer (FLEX) space mission to study the complete SIF signal of terrestrial vegetation. The interpretation of the complete SIF signal at the 300 m FLEX pixel will be a huge challenge, in particular deriving information at the farm scale. First, we will study the SIF signal with the so-called FluorSpec (a sub-nanometer spectrometer with 0.14 nm bandwidth) by performing measurements in the field. Secondly, since unmanned aerial vehicles (UAV) are very versatile platforms, we will use such a platform equipped with the FluorSpec to fill the gap between canopy-based SIF measurements and the FLEX level in order to develop understanding and validation of the FLEX signal.
- Calculate red and far-red SIF, based on available retrieval methods using the full SIF signal, based on field measurements
- Test the applicability of the new UAV-based SIF measurements
- Study the complementary use of reflectance and SIF measurements on agricultural crops
This topic can be split in multiple thesis topics.
- Zarco-Tejada, P.J., González-Dugo, M.V., & Fereres, E. (2016). Seasonal stability of chlorophyll fluorescence quantified from airborne hyperspectral imagery as an indicator of net photosynthesis in the context of precision agriculture. Remote Sensing of Environment, 179, 89-103, doi: 10.1016/j.rse.2016.03.024
- Rossini, M., Meroni, M., Celesti, M., Cogliati, S., Julitta, T., Panigada, C., Rascher, U., van der Tol, C., & Colombo, R. (2016). Analysis of red and far-red sun-induced chlorophyll fluorescence and their ratio in different canopies based on observed and modeled data. Remote Sensing, 8, doi: 10.3390/rs8050412
- Smorenburg, K., Courrèges-Lacoste, G.B., Berger, M., Buschmann, C., Court, A., Del Bello, U., Langsdorf, G., Lichtenthaler, H.K., Sioris, C., Stoll, M.P., & Visser, H. (2002). Remote sensing of solar induced fluorescence of vegetation. Proceedings of SPIE - The International Society for Optical Engineering, 4542, 178-190, doi: 10.1117/12.454193
Theme(s): Sensing & measuring