Capturing Effects of Crop Growth on the Atmosphere in the Southern Great Plains

The Science

Winter wheat, which is planted in fall and harvested in early summer, has a different growth cycle and responds to environmental stresses differently from summer crops. Researchers implemented new algorithms and parameterizations in the Community Land Model (CLM) to capture the atmospheric influence of winter wheat, the dominant crop cover in the Southern Great Plains.

The Impact

This new field-tested modeling capability enables Earth system models to more accurately represent the unique growth timing of winter wheat and therefore the role of vegetation in land-atmosphere coupling in wheat-growing regions.  Winter wheat is a staple crop for global food security, and is the dominant vegetation cover for a significant fraction of Earth’s croplands. Accurate simulation of winter wheat growth is not only crucial for future yield prediction, but also for accurately predicting the energy and water cycles for winter wheat dominated regions.

Summary

Researchers modified the winter wheat sub-model in the Community Land Model (CLM) to better simulate winter wheat growth and yield. They calibrated three key parameters and modified the grain carbon allocation algorithm for simulations at the DOE Atmospheric Radiation Measurement (ARM) scientific user facility Southern Great Plains site, and validated the model performance at eight additional sites across North America. The new winter wheat model improved the prediction of monthly variation in leaf area index, and reduced latent heat flux and net ecosystem exchange root mean square error (RMSE) by 41 and 35% during the spring growing season.  While the model accurately simulated the interannual variation in yield at the ARM site, it underestimated yield at sites and in regions (northwestern and southeastern US) with historically greater yields.

Principal Investigator(s)

Lara Kueppers
UC Berkeley/Lawrence Berkeley National Laboratory
[email protected]

Margaret Torn
Lawrence Berkeley National Laboratory 
[email protected]

Funding

This material is based upon work supported by the U.S. Department of Energy, Office of Science, Office of Biological and Environmental Research, Atmospheric System Research, under contract number DE-AC02-05CH11231. Funding for the US-ARM AmeriFlux site was provided by the U.S. Department of Energy’s Office of Science. This research used resources of the National Energy Research Scientific Computing Center, a DOE Office of Science User Facility supported by the Office of Science of the U.S. Department of Energy under contract no. DE-AC02-05CH11231. In addition, funding for AmeriFlux data resources was provided by the U.S. Department of Energy’s Office of Science.

References

Y. Lu, Williams, I. N., Bagley, J. E., Torn, M. S. & Kueppers, L. M. Representing winter wheat in the Community Land Model (version 4.5). Geoscientific Model Development 10, 1873-1888 (2017), doi:10.5194/gmd-10-1873-2017.