Multi-hypothesis Representation of Leaf Level Photosynthesis Reveals the Sources of Variation in Terrestrial Biosphere Model Representation of CO2 Assimilation
Abstract
Terrestrial Biosphere Models (TBMs) represent photosynthesis with ostensibly the same equations but have been shown to have markedly different modeled responses to key environmental drivers. These responses are the primary mechanism by which plants respond to, and modulate, global change and are critical to understand and represent accurately in TBMs. However, it is challenging to identify the underlying causes of variation in modeled assimilation simply by comparing model outputs. To address this challenge, we examined the technical descriptions and code underlying the representation of photosynthesis in nine major TBMs and replicated their underlying model hypotheses and assumptions in a new tool - the Multi Assumption Analysis Testbed (MAAT). This enabled us to replicate the assembly of hypotheses associated with representation of photosynthesis in the original TBMs. We then used MAAT to predict the response of leaf level photosynthesis to irradiance, atmospheric CO2 concentration, vapor pressure deficit, and temperature in a tropical forest plant functional type as represented by each TBM. In a final step we progressively unified individual TBM hypotheses and assumptions thus revealing the model choices that underlie variation among the TBMs in their representation of photosynthesis and the resulting leaf level responses to key environmental drivers.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2019
- Bibcode:
- 2019AGUFM.H12H..06R
- Keywords:
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- 1847 Modeling;
- HYDROLOGY;
- 1873 Uncertainty assessment;
- HYDROLOGY;
- 1880 Water management;
- HYDROLOGY;
- 1916 Data and information discovery;
- INFORMATICS