MARCOTTE, Mme Coralie (2024) Improving the representation of plant carbon uptake and transpiration in the ORCHIDEE land surface model during drought events using multiple proxies PRE - Research Project, ENSTA.
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Abstract
Gross Primary Production (GPP) represent the absorption of CO2 by vegetation during photosynthesis. Climate models, especially land surface models such as ORCHIDEE, are useful for simulating carbon exchanges between land surfaces and the atmosphere, such as GPP, which lacks direct observation data. To improve the representation of GPP, this project studies the integration of two proxies into the ORCHIDEE model, Solar Induced Fluorescence (SIF), emitted by plants, and Carbonyl Sulfide (COS), a gas absorbed by vegetation. Using observations of variables, the parameters of the models for these two proxies and the GPP model have been optimised by assimilating observed data, for two specific sites. The results highlight the importance of the proxies in improving the simulated GPP, although this is not systematic. The proxies nevertheless help to better constrain other essential variables in the model, such as stomatal conductance and evapo-transpiration. A re-evaluation of the SIF model, or having data available on more sites, would provide more benefits from the SIF and COS. Finally, a new proxy for providing new information on vegetation activity, the Vegetation Optical Depth (VOD), has been studied at one site. The correlations obtained in particular with two model variables, Leaf Area Index (LAI) and stomatal conductance, pave the way for a promising implementation of a VOD model in ORCHIDEE.
Item Type: | Thesis (PRE - Research Project) |
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Uncontrolled Keywords: | Climate change, Gross Primary Productivity (GPP), Solar Induced Fluorescence (SIF), Carbo- nyl Sulfide (COS), Land surface model, Data assimilation, Vegetation Optical Depth (VOD) |
Subjects: | Earth Sciences and Environmental Engineering |
ID Code: | 10259 |
Deposited By: | Hugo Marcotte |
Deposited On: | 09 sept. 2024 15:17 |
Dernière modification: | 09 sept. 2024 15:17 |
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