Potential of MODIS EVI and surface temperature for directly estimating per-pixel ecosystem C fluxes

We tested the potential of estimating per-pixel gross primary production (GPP) directly from the MODIS enhanced vegetation index (EVI) and respiration directly from MODIS surface temperature (MOD11). Carbon flux data were obtained from 10 eddy covariance tower sites representing a wide range of North American vegetations. The correlation between across-site tower GPP and EVI was comparable ( r = 0.77) to that between tower GPP and MOD17-GPP ( r = 0.73), suggesting that EVI could be used to provide reasonably accurate direct estimates of GPP on a truly per-pixel basis. There was also a strong relationship (r(2) = 0.67) between respiration and surface temperature of dense vegetation, suggesting that estimation of net ecosystem exchange ( NEE) may be possible with relatively simple pixel based models, at least for some vegetation types.