Using model reduction to predict the soil-surface C<sup>18</sup>OO flux: an example of representing complex biogeochemical dynamics in a computationally efficient manner
Abstract
Abstract. Earth System Models (ESMs) must calculate large-scale interactions between the land and atmosphere while accurately characterizing fine-scale spatial heterogeneity in water, carbon, and nutrient dynamics. We present here a high-dimensional model representation (HDMR) approach that allows detailed process representation of a coupled carbon and water tracer (the δ18O value of the soil-surface CO2 flux (δFs)) in a computationally tractable manner. δFs depends on the δ18O value of soil water, soil moisture, soil temperature, and soil CO2 production (all of which are depth-dependent), and the δ18O value of above-surface CO2. We tested the HDMR approach over a growing season in a C4-dominated pasture using two vertical soil discretizations. The difference between the HDMR approach and the full model solution in the three-month integrated isoflux was less than 0.2% (0.5 mol m−2‰), and the approach is up to 100 times faster than the full numerical solution. This type of model reduction approach allows representation of complex coupled biogeochemical processes in regional and global climate models and can be extended to characterize subgrid-scale spatial heterogeneity.
Publisher
Copernicus GmbH
Reference51 articles.
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