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

The northern terrestrial net ecosystem carbon bal­ ance (NECB) is contingent on inpnts from vegetation gross primary prodnctivity (GPP) to offset the ecosystem respi­ ration (Reco) of carbon dioxide (CO2 ) and methane (CH4 ) emissions, bnt an effective framework to monitor the re­ gional Arctic NECB is lacking. We modified a terrestrial car­ bon llnx (TCF) model developed for satellite remote sens­ ing applications to evalnate wetland CO2 and CH4 llnxes over pan-Arctic eddy covariance (EC) llnx tower sites. The TCF model estimates GPP, CO2 and CH4 emissions nsing in sitn or remote sensing and reanalysis-based climate data as inpnts. The TCF model simnlations nsing in sitn data explained > 7 0 % of the r^ variability in the 8 day cnmnlative EC measmed llnxes. Model simnlations nsing coarser satellite (MODIS) and reanalysis (MERRA) records acconnted for approximately 69 % and 75 % of the respective r^ variability in the tower CO2 and CH4 records, with cor­ responding RMSE nncertainties of < 1 .3 g C m -2 d i (CO2 ) and 18.2mgCm“ ̂d“ ̂ (CH4 ). Althongh the estimated annnal CH4 emissions were small (< 18gC m “ ^yr“ )̂ relative to Reco (> 180gC m “^yr“ ^), they rednced the across-site NECB by 23 % and contribnted to a global warming potential of approximately 165 ± 128gC02eqm “ ^yr“ ̂when consid­ ered over a 100 year time span. This model evalnation indi­ cates a strong potential for nsing the TCF model approach to docnment landscape-scale variability in CO2 and CH4 llnxes, and to estimate the NECB for northern peatland and tnndra ecosystems.