A satellite data driven biophysical modeling approach for estimating northern peatland and tundra CO2 and CH4 fluxes

[摘要] The northern terrestrial net ecosystem carbon balance (NECB) is contingent oninputs from vegetation gross primary productivity (GPP) to offset theecosystem respiration (R_eco) of carbon dioxide (CO₂) andmethane (CH₄) emissions, but an effective framework to monitor theregional Arctic NECB is lacking. We modified a terrestrial carbon flux (TCF)model developed for satellite remote sensing applications to evaluate wetlandCO₂ and CH₄ fluxes over pan-Arctic eddy covariance (EC) flux towersites. The TCF model estimates GPP, CO₂ and CH₄ emissions using insitu or remote sensing and reanalysis-based climate data as inputs. The TCFmodel simulations using in situ data explained > 70% of the r²variability in the 8 day cumulative EC measured fluxes. Model simulationsusing coarser satellite (MODIS) and reanalysis (MERRA) records accounted forapproximately 69% and 75% of the respective r² variability inthe tower CO₂ and CH₄ records, with corresponding RMSEuncertainties of ≤ 1.3 g C m⁻² d⁻¹ (CO₂) and18.2 mg C m⁻² d⁻¹ (CH₄). Although the estimated annualCH₄ emissions were small (< 18 g C m⁻² yr⁻¹) relativeto R_eco (> 180 g C m⁻² yr⁻¹), they reduced theacross-site NECB by 23% and contributed to a global warming potential ofapproximately 165 ± 128 g CO₂eq m⁻² yr⁻¹ whenconsidered over a 100 year time span. This model evaluation indicates astrong potential for using the TCF model approach to document landscape-scalevariability in CO₂ and CH₄ fluxes, and to estimate the NECB fornorthern peatland and tundra ecosystems.

[学科分类] 地球化学与岩石