Validation of the Community Land Model Version 5 Over the Contiguous United States (CONUS) Using In Situ and Remote Sensing Data Sets

Abstract

The Community Land Model (CLM) is an effective tool to simulate the biophysical and biogeochemical processes and their interactions with the atmosphere. Although CLM version 5 (CLM5) constitutes various updates in these processes, its performance in simulating energy, water and carbon cycles over the contiguous United States (CONUS) at scales which land surface changes and hydrometeorological and hydroclimatological applications are more locally relevant is yet to be assessed. In this study, we conducted three simulations at 0.125° during 1979–2018 over the CONUS using different configurations of CLM, namely CLM5‐biogeochemistry (CLM5BGC), CLM4.5BGC, and CLM5‐satellite phenology (CLM5SP). We validated and compared their simulations against multiple remote‐sensed and in situ data sets. Overall, the parametric and structural updates (e.g., carbon cost for nitrogen uptake, variable soil thickness, dry surface layer) in CLM5 improve its ability in capturing terrestrial biogeochemical dynamics. The low evapotranspiration in CLM5BGC is associated with biases in simulating vegetation phenological characteristics rather than soil water limitations. The mismatch between CLM5BGC‐simulated peak leaf area index and reference data can be attributed to CLM5BGC's inability in simulating phenology of trees and grasses. The differences between CLM‐simulated irrigation and reference estimates can be attributed to differences between processes represented in models and in reality, and uncertainties in input and validation data sets. Evaluation against observations at small catchments suggest that hydrologic parameters needed to be calibrated to improve simulations of runoff, especially subsurface runoff. Additional efforts are needed to incorporate spatially distributed plant phenology and physiology parameters and regional‐specific agricultural management practices (e.g., planting and harvest).

Revegetation Does Not Decrease Water Yield in the Loess Plateau of China

“…Without changes in atmospheric circulation, P increase might not outpace E increase and the overall water budget following revegetation would be different. In addition to P uncertainties, additional uncertainties may come from E , given the large structural and parameterization uncertainties in existing E products (Cheng et al., 2021; X. Liu et al., 2020; Trugman et al., 2018), which will further complicate the water budget analysis. A more comprehensive uncertainty quantification warrants further research, which should consider all ensembles of E , not just the ensemble mean.…”

Modeling the Joint Effects of Vegetation Characteristics and Soil Properties on Ecosystem Dynamics in a Panama Tropical Forest

“…This is because the model can simulate a better plant productivity (Figure 2b) and water budget including ET (Figure 2d), soil moisture (Figure 2e), and runoff (Figure 2f). These results have important implications as accurate predictions of energy partitioning are necessary to represent the biophysical effect of land surface processes at regional scale, which can feedback to climate through land‐atmosphere interactions (Bonan, 2008; Cheng et al., 2021).…”

Future bioenergy expansion could alter carbon sequestration potential and exacerbate water stress in the United States

“…The 30-year historical forcing data are recycled for 800 years to spin up the model for the carbon and nitrogen pools to reach equilibrium. The performance of CLM5 in simulating land surface fluxes over the CONUS from 1979 to 2018 has been evaluated against various in situ and remote sensing datasets in an earlier study ( 56 ). Two regions (i.e., Pacific Northwest and California) are selected for further analyses due to their similar climate but distinct magnitudes of bioenergy expansion (fig.…”