Abstract
Abstract. Accurate simulations of soil respiration and carbon dioxide (CO2) fluxes are critical to project global biogeochemical cycles and the magnitude of carbon–climate feedbacks in Earth system models (ESMs). Currently, soil respiration is not represented well in ESMs, and few studies have attempted to address this deficiency. In this study, we evaluated the simulation of soil respiration in the Energy Exascale Earth System Model (E3SM) land model version 0 (ELMv0) using long-term observations from the Missouri Ozark AmeriFlux (MOFLUX) forest site in the central US. Simulations using the default model parameters underestimated soil water potential (SWP) during peak growing seasons and overestimated SWP during non-growing seasons and consequently underestimated annual soil respiration and gross primary production (GPP). A site-specific soil water retention curve greatly improved model simulations of SWP, GPP, and soil respiration. However, the model continued to underestimate the seasonal and interannual variabilities and the impact of the extreme drought in 2012. Potential reasons may include inadequate representations of vegetation mortality, the soil moisture function, and the dynamics of microbial organisms and soil macroinvertebrates. Our results indicate that the simulations of mean annual GPP and soil respiration can be significantly improved by better model representations of the soil water retention curve.
Highlights
Soils store over twice as much carbon (C) as the atmosphere (Chapin III et al, 2011)
For the upper 30 cm of soil, the ELMv0 simulations using the default Clapp and Hornberger model tended to underestimate the soil water potential (SWP) when volumetric water content (VWC) was less than 15 % (Fig. 1a), while SWP rapidly approached zero when VWC was greater than 25 % (Fig. 1a)
The simulated Soil respiration (SR) had smaller interannual variability compared to the observations
Summary
Soils store over twice as much carbon (C) as the atmosphere (Chapin III et al, 2011). Soil respiration (SR) is the second largest C flux between terrestrial ecosystems and the atmosphere (Luo and Zhou, 2006). An accurate simulation of SR is critical for projecting terrestrial C status, and climate change, in Earth system models (ESMs) (IPCC, 2013). Despite significant experimental data accumulation and model development during the past decades, simulations of soil CO2 efflux to the atmosphere still have a high degree of uncertainty (Friedlingstein et al, 2006; Jones et al, 2013; Todd-Brown et al, 2013, 2014; Tian et al, 2015), calling for comprehensive assessments of model performance against observational data. Liang et al.: Evaluating the E3SM land model version 0
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
