Overview
Andre is working on the developments in the UK's leading land surface model (JULES), which forms the land part of the Met Office climate models. He specialises in terrestrial carbon and nutrients dynamics. During his research in C-CASCADES project, he developed an extension to Joint UK Land Environment Simulator (JULES) which includes representation of processes related to DOC in soil and its transport out of soil to the river system (JULES-DOCM).
He is currently enrolled in CRESCENDO and AFEX projects to include representation of N and P in JULES model. The new developments include the N and P fluxes within vegetation and soil components as well as specification of pools and processes related to N and P cycling within soil column. He obtained his PhD from Exeter University in 2019, where he studied earth system modelling.
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Journal articles
Nakhavali M, Lauerwald R, Regnier P, Guenet B, Chadburn S, Friedlingstein P (2020). Leaching of dissolved organic carbon from mineral soils plays a significant role in the terrestrial carbon balance.
Glob Chang BiolAbstract:
Leaching of dissolved organic carbon from mineral soils plays a significant role in the terrestrial carbon balance.
The leaching of dissolved organic carbon (DOC) from soils to the river network is an overlooked component of the terrestrial soil C budget. Measurements of DOC concentrations in soil, runoff and drainage are scarce and their spatial distribution highly skewed towards industrialized countries. The contribution of terrestrial DOC leaching to the global-scale C balance of terrestrial ecosystems thus remains poorly constrained. Here, using a process based, integrative, modelling approach to upscale from existing observations, we estimate a global terrestrial DOC leaching flux of 0.28 ± 0.07 Gt C year-1 which is conservative, as it only includes the contribution of mineral soils. Our results suggest that globally about 15% of the terrestrial Net Ecosystem Productivity (NEP, calculated as the difference between Net Primary Production and soil respiration) is exported to aquatic systems as leached DOC. In the tropical rainforest, the leached fraction of terrestrial NEP even reaches 22%. Furthermore, we simulated spatial-temporal trends in DOC leaching from soil to the river networks from 1860 to 2010. We estimated a global increase in terrestrial DOC inputs to river network of 35 Tg C year-1 (14%) from 1860 to 2010. Despite their low global contribution to the DOC leaching flux, boreal regions have the highest relative increase (28%) while tropics have the lowest relative increase (9%) over the historical period (1860s compared to 2000s). The results from our observationally constrained model approach demonstrate that DOC leaching is a significant flux in the terrestrial C budget at regional and global scales.
Abstract.
Author URL.
Nakhavali M, Friedlingstein P, Lauerwald R, Tang J, Chadburn S, Camino-Serrano M, Guenet B, Harper A, Walmsley D, Peichl M, et al (2018). Representation of dissolved organic carbon in the JULES land surface model (vn4.4-JULES-DOCM).
Geoscientific Model Development,
11(2), 593-609.
Abstract:
Representation of dissolved organic carbon in the JULES land surface model (vn4.4-JULES-DOCM)
© Author(s) 2018. Current global models of the carbon (C) cycle consider only vertical gas exchanges between terrestrial or oceanic reservoirs and the atmosphere, thus not considering the lateral transport of carbon from the continents to the oceans. Therefore, those models implicitly consider all of the C which is not respired to the atmosphere to be stored on land and hence overestimate the land C sink capability. A model that represents the whole continuum from atmosphere to land and into the ocean would provide a better understanding of the Earth's C cycle and hence more reliable historical or future projections. A first and critical step in that direction is to include processes representing the production and export of dissolved organic carbon in soils. Here we present an original representation of dissolved organic C (DOC) processes in the Joint UK Land Environment Simulator (JULES-DOCM) that integrates a representation of DOC production in terrestrial ecosystems based on the incomplete decomposition of organic matter, DOC decomposition within the soil column, and DOC export to the river network via leaching. The model performance is evaluated in five specific sites for which observations of soil DOC concentration are available. Results show that the model is able to reproduce the DOC concentration and controlling processes, including leaching to the riverine system, which is fundamental for integrating terrestrial and aquatic ecosystems. Future work should include the fate of exported DOC in the river system as well as DIC and POC export from soil.
Abstract.
Full text.
Publications by year
2020
Nakhavali M, Lauerwald R, Regnier P, Guenet B, Chadburn S, Friedlingstein P (2020). Leaching of dissolved organic carbon from mineral soils plays a significant role in the terrestrial carbon balance.
Glob Chang BiolAbstract:
Leaching of dissolved organic carbon from mineral soils plays a significant role in the terrestrial carbon balance.
The leaching of dissolved organic carbon (DOC) from soils to the river network is an overlooked component of the terrestrial soil C budget. Measurements of DOC concentrations in soil, runoff and drainage are scarce and their spatial distribution highly skewed towards industrialized countries. The contribution of terrestrial DOC leaching to the global-scale C balance of terrestrial ecosystems thus remains poorly constrained. Here, using a process based, integrative, modelling approach to upscale from existing observations, we estimate a global terrestrial DOC leaching flux of 0.28 ± 0.07 Gt C year-1 which is conservative, as it only includes the contribution of mineral soils. Our results suggest that globally about 15% of the terrestrial Net Ecosystem Productivity (NEP, calculated as the difference between Net Primary Production and soil respiration) is exported to aquatic systems as leached DOC. In the tropical rainforest, the leached fraction of terrestrial NEP even reaches 22%. Furthermore, we simulated spatial-temporal trends in DOC leaching from soil to the river networks from 1860 to 2010. We estimated a global increase in terrestrial DOC inputs to river network of 35 Tg C year-1 (14%) from 1860 to 2010. Despite their low global contribution to the DOC leaching flux, boreal regions have the highest relative increase (28%) while tropics have the lowest relative increase (9%) over the historical period (1860s compared to 2000s). The results from our observationally constrained model approach demonstrate that DOC leaching is a significant flux in the terrestrial C budget at regional and global scales.
Abstract.
Author URL.
2018
Nakhavali M, Friedlingstein P, Lauerwald R, Tang J, Chadburn S, Camino-Serrano M, Guenet B, Harper A, Walmsley D, Peichl M, et al (2018). Representation of dissolved organic carbon in the JULES land surface model (vn4.4-JULES-DOCM).
Geoscientific Model Development,
11(2), 593-609.
Abstract:
Representation of dissolved organic carbon in the JULES land surface model (vn4.4-JULES-DOCM)
© Author(s) 2018. Current global models of the carbon (C) cycle consider only vertical gas exchanges between terrestrial or oceanic reservoirs and the atmosphere, thus not considering the lateral transport of carbon from the continents to the oceans. Therefore, those models implicitly consider all of the C which is not respired to the atmosphere to be stored on land and hence overestimate the land C sink capability. A model that represents the whole continuum from atmosphere to land and into the ocean would provide a better understanding of the Earth's C cycle and hence more reliable historical or future projections. A first and critical step in that direction is to include processes representing the production and export of dissolved organic carbon in soils. Here we present an original representation of dissolved organic C (DOC) processes in the Joint UK Land Environment Simulator (JULES-DOCM) that integrates a representation of DOC production in terrestrial ecosystems based on the incomplete decomposition of organic matter, DOC decomposition within the soil column, and DOC export to the river network via leaching. The model performance is evaluated in five specific sites for which observations of soil DOC concentration are available. Results show that the model is able to reproduce the DOC concentration and controlling processes, including leaching to the riverine system, which is fundamental for integrating terrestrial and aquatic ecosystems. Future work should include the fate of exported DOC in the river system as well as DIC and POC export from soil.
Abstract.
Full text.
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