Predicted Land Carbon Dynamics Are Strongly Dependent on the Numerical Coupling of Nitrogen Mobilizing and Immobilizing Processes: A Demonstration with the E3SM Land Model

Tang, Jinyun; Riley, William J.

doi:10.1175/ei-d-17-0023.1

Cited by 19 publications

(24 citation statements)

References 59 publications

(56 reference statements)

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“…Some of them also consider the phosphorus cycle (Goll et al, ; Wang et al, ; Yang et al, ). Although these models were built with the concept that nutrient deficiency limits the carbon cycle, large uncertainties stem from how nutrient limitations are implemented (Medlyn et al, ; Tang & Riley, ; Zaehle et al, ).…”

Section: Introductionmentioning

confidence: 99%

Representing Nitrogen, Phosphorus, and Carbon Interactions in the E3SM Land Model: Development and Global Benchmarking

Zhu

Riley

Tang

et al. 2019

J Adv Model Earth Syst

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110

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Over the past several decades, the land modeling community has recognized the importance of nutrient regulation on the global terrestrial carbon cycle. Implementations of nutrient limitation in land models are diverse, varying from applying simple empirical down-regulation of potential gross primary productivity under nutrient deficit conditions to more mechanistic treatments. In this study, we introduce a new approach to model multinutrient (nitrogen [N] and phosphorus [P]) limitations in the Energy Exascale Earth System Model (E3SM) Land Model version 1 (ELMv1-ECA). The development is grounded on (1) advances in representing multiple-consumer, multiple-nutrient competition; (2) a generic dynamic allocation scheme based on water, N, P, and light availability; (3) flexible plant CNP stoichiometry; (4) prognostic treatment of N and P constraints on several carbon cycle processes; and (5) global data sets of plant physiological traits. Through benchmarking the model against best knowledge of global plant and soil carbon pools and fluxes, we show that our implementation of nutrient constraints on the present-day carbon cycle is robust at the global scale. Compared with predecessor versions, ELMv1-ECA better predicts global-scale gross primary productivity, ecosystem respiration, leaf area index, vegetation biomass, soil carbon stocks, evapotranspiration, N 2 O emissions, and NO 3 leaching. Factorial experiments indicate that representing the phosphorus cycle improves modeled carbon fluxes, while considering dynamic allocation improves modeled carbon stock density. We also highlight the value of using the International Land Model Benchmarking (ILAMB) package to evaluate and document performance during model development.

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Section: Introductionmentioning

confidence: 99%

Representing Nitrogen, Phosphorus, and Carbon Interactions in the E3SM Land Model: Development and Global Benchmarking

Zhu

Riley

Tang

et al. 2019

J Adv Model Earth Syst

Self Cite

110

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show abstract

“…Here we demonstrated how continuous and discrete time approaches can reconstruct soil radiocarbon profiles using only land model 12 C stocks and fluxes and atmospheric 14 C values. We applied the approach here to the ELMv1‐ECA model (Riley et al, ; Tang & Riley, ; Zhu et al, ), which explicitly represents soil organic matter 14 C dynamics with seven soil pools and ten vertical layers, and showed that our approach very accurately reproduces the full model simulations (bias

< 0.01

%). The approach can also be used for the new suite of CMIP6 simulations to evaluate whether the models are accurately representing soil C age and transit time, in addition to soil carbon stock (He et al, ; Lawrence et al, ).…”

Section: Discussionmentioning

confidence: 98%

Mathematical Reconstruction of Land Carbon Models From Their Numerical Output: Computing Soil Radiocarbon From C Dynamics

Metzler

Zhu

Riley

et al. 2020

J Adv Model Earth Syst

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Radiocarbon ( 14 C) is a powerful tracer of the global carbon cycle that is commonly used to assess carbon cycling rates in various Earth system reservoirs and as a benchmark to assess model performance. Therefore, it has been recommended that Earth System Models (ESMs) participating in the Coupled Model Intercomparison Project Phase 6 report predicted radiocarbon values for relevant carbon pools. However, a detailed representation of radiocarbon dynamics may be an impractical burden on model developers. Here, we present an alternative approach to compute radiocarbon values from the numerical output of an ESM that does not explicitly represent these dynamics. The approach requires computed 12 C stocks and fluxes among all carbon pools for a particular simulation of the model. From this output, a time-dependent linear compartmental system is computed with its respective state-transition matrix. Using transient atmospheric 14 C values as inputs, the state-transition matrix is then applied to compute radiocarbon values for each pool, the average value for the entire system, and component fluxes. We demonstrate the approach with ELMv1-ECA, the land component of an ESM model that explicitly represents 12 C, and 14 C in 7 soil pools and 10 vertical layers. Results from our proposed method are highly accurate (relative error <0.01%) compared with the ELMv1-ECA 12 C and 14 C predictions, demonstrating the potential to use this approach in CMIP6 and other model simulations that do not explicitly represent 14 C.Plain Language Summary Models representing ecosystem carbon dynamics are generally complex and difficult to analyze. Comparing different models with different structures is even more challenging due to the variety of processes represented in the models. However, it is possible to use the numerical output of models to reconstruct the original structure using a common mathematical framework. In this manuscript, we demonstrate this approach and apply it to compute radiocarbon dynamics of a land carbon model. The proposed approach can reconstruct the carbon and radiocarbon dynamics of the original model very accurately and can be used to study system-level dynamics of complex contrasting models.

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“…Golaz et al () described simulations performed using the fully coupled E3SM at resolution of ~100 km for the atmosphere and land, 30–60 km for the ocean and sea ice, and 0.5° for the river. The E3SM land model (ELM; Drewniak, ; Liang et al, ; Ricciuto et al, ; Tang & Riley, ) was developed from the Community Land Model version 4.5 (CLM4.5; Oleson et al, ) and is coupled to MOSART using one‐way coupling. Each MOSART computational unit (grid) includes subgrid hillslopes, subgrid tributaries, and a single main channel which connects the local grid cell with the upstream/downstream grid cells through the river network.…”

Section: Methods and Datamentioning

confidence: 99%

Flood Inundation Generation Mechanisms and Their Changes in 1953–2004 in Global Major River Basins

et al. 2019

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Despite the serious threats posed by floods, the driving mechanisms of floods are still not well understood. Here we apply a physically based inundation model coupled with a river routing model (Model for Scale Adaptive River Transport (MOSART)) within the Energy Exascale Earth System Model (E3SM) framework to investigate flood inundation dynamics. After calibration using observed streamflow and satellite-derived flood extent, the model is used to simulate global flood inundation from 1953 to 2004. The mean date and seasonality of annual maximum flood, defined based on flood extent, exhibit significant regional differences across 16 major basins. Generally, soil moisture and monthly maximum daily rainfall (MMR) are the dominant drivers of flood in tropical basins while monthly maximum daily snowmelt (MMS) is the dominant driver in high-latitude basins. From 1953From -1982From to 1975From -2004 changes in flood generation mechanisms are found in some basins such as Amazon, Lena, Yenisey, and Kolyma. Analysis of the rainfall seasonality and water balance at grid scale reveals a stronger rainfall seasonality in the Amazon during the later period that increases the synchrony between extreme rainfall and wet soil. With high antecedent soil moisture coinciding with rainfall, MMR contributes more to flood in the later period. Fewer extreme rainfall events and increasing soil moisture reduced the contribution of MMR and increased the role of MMS in floods in the Lena and Yenisey basins, respectively. Lastly, increased soil moisture and frequency of large MMS reduced the contribution of the latter to floods in the Kolyma basin. Key Points: • Global flood inundation dynamics are simulated with a physically based inundation model coupled with a river routing model • Flood date, seasonality, and generation mechanisms show large spatial variability across 16 major river basins around the world • Rainfall importance to flood decreased in most rainfall-driven basins and snowmelt importance decreased at high latitudes in

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Predicted Land Carbon Dynamics Are Strongly Dependent on the Numerical Coupling of Nitrogen Mobilizing and Immobilizing Processes: A Demonstration with the E3SM Land Model

Cited by 19 publications

References 59 publications

Representing Nitrogen, Phosphorus, and Carbon Interactions in the E3SM Land Model: Development and Global Benchmarking

Representing Nitrogen, Phosphorus, and Carbon Interactions in the E3SM Land Model: Development and Global Benchmarking

Mathematical Reconstruction of Land Carbon Models From Their Numerical Output: Computing Soil Radiocarbon From C Dynamics

Flood Inundation Generation Mechanisms and Their Changes in 1953–2004 in Global Major River Basins

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