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Journal Article

Addressing biases in Arctic–boreal carbon cycling in the Community Land Model Version 5

Authors

Birch,  Leah
External Organizations;

Schwalm,  Christopher R.
External Organizations;

Natali,  Sue
External Organizations;

Lombardozzi,  Danica
External Organizations;

Keppel-Aleks,  Gretchen
External Organizations;

Watts,  Jennifer
External Organizations;

Lin,  Xin
External Organizations;

Zona,  Donatella
External Organizations;

Oechel,  Walter
External Organizations;

/persons/resource/tsachs

Sachs,  T.
1.4 Remote Sensing, 1.0 Geodesy, Departments, GFZ Publication Database, Deutsches GeoForschungsZentrum;

Black,  Thomas Andrew
External Organizations;

Rogers,  Brendan M.
External Organizations;

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Fulltext (public)

5006946.pdf
(Publisher version), 5MB

Supplementary Material (public)
There is no public supplementary material available
Citation

Birch, L., Schwalm, C. R., Natali, S., Lombardozzi, D., Keppel-Aleks, G., Watts, J., Lin, X., Zona, D., Oechel, W., Sachs, T., Black, T. A., Rogers, B. M. (2021): Addressing biases in Arctic–boreal carbon cycling in the Community Land Model Version 5. - Geoscientific Model Development, 14, 6, 3361-3382.
https://doi.org/10.5194/gmd-14-3361-2021


Cite as: https://gfzpublic.gfz-potsdam.de/pubman/item/item_5006946
Abstract
The Arctic–boreal zone (ABZ) is experiencing amplified warming, actively changing biogeochemical cycling of vegetation and soils. The land-to-atmosphere fluxes of CO2 in the ABZ have the potential to increase in magnitude and feedback to the climate causing additional large-scale warming. The ability to model and predict this vulnerability is critical to preparation for a warming world, but Earth system models have biases that may hinder understanding of the rapidly changing ABZ carbon fluxes. Here we investigate circumpolar carbon cycling represented by the Community Land Model 5 (CLM5.0) with a focus on seasonal gross primary productivity (GPP) in plant functional types (PFTs). We benchmark model results using data from satellite remote sensing products and eddy covariance towers. We find consistent biases in CLM5.0 relative to observational constraints: (1) the onset of deciduous plant productivity to be late; (2) the offset of productivity to lag and remain abnormally high for all PFTs in fall; (3) a high bias of grass, shrub, and needleleaf evergreen tree productivity; and (4) an underestimation of productivity of deciduous trees. Based on these biases, we focus on model development of alternate phenology, photosynthesis schemes, and carbon allocation parameters at eddy covariance tower sites. Although our improvements are focused on productivity, our final model recommendation results in other component CO2 fluxes, e.g., net ecosystem exchange (NEE) and terrestrial ecosystem respiration (TER), that are more consistent with observations. Results suggest that algorithms developed for lower latitudes and more temperate environments can be inaccurate when extrapolated to the ABZ, and that many land surface models may not accurately represent carbon cycling and its recent rapid changes in high-latitude ecosystems, especially when analyzed by individual PFTs.