Evaluation of the Latest MODIS GPP Products across Multiple Biomes Using Global Eddy Covariance Flux DataReport as inadecuate


Evaluation of the Latest MODIS GPP Products across Multiple Biomes Using Global Eddy Covariance Flux Data


Evaluation of the Latest MODIS GPP Products across Multiple Biomes Using Global Eddy Covariance Flux Data - Download this document for free, or read online. Document in PDF available to download.

1

Laboratory of Critical Zone Evolution, School of Earth Sciences, China University of Geosciences, Wuhan 430074, China

2

School of Resource and Environmental Science, Wuhan University, Wuhan 430079, China



These authors contributed equally to this work.





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Academic Editors: Alfredo R. Huete and Prasad S. Thenkabail

Abstract The latest MODIS GPP gross primary productivity product, MOD17A2H, has great advantages over the previous version, MOD17A2, because the resolution increased from 1000 m to 500 m. In this study, MOD17A2H GPP was assessed using the latest eddy covariance EC flux data FLUXNET2015 Dataset at eighteen sites in six ecosystems across the globe. The sensitivity of MOD17A2H GPP to the meteorology dataset and the fractional photosynthetically- active radiation FPAR product was explored by introducing site meteorology observations and improved Global Land Surface Satellite GLASS Leaf Area Index LAI products. The results showed that MOD17A2H GPP underestimated flux-derived GPP at most sites. Its performance in estimating annual GPP was poor R2 = 0.62 and even worse over eight days R2 = 0.52. For the MOD17A2H algorithm, replacing the reanalysis meteorological datasets with the site meteorological measurements failed to improve the estimation accuracies. However, great improvements in estimating the site-based GPP were gained by replacing MODIS FPAR with GLASS FPAR. This indicated that in the existing MOD17A2H product, the errors were originated more from FPAR than the meteorological data. We further examined the potential error contributions from land cover classification and maximum light use efficiency εmax. It was found that the current land cover classification scheme exhibited frequent misclassification errors. Moreover, the εmax value assigned in MOD17A2H was much smaller than the inferred εmax value. Therefore, the qualities of FPAR and land cover classification datasets should be upgraded, and the εmax value needs to be adjusted to provide more accurate GPP estimates using MOD17A2H for global ecosystems. View Full-Text

Keywords: GPP; MOD17A2H; validation; FLUXNET2015; global ecosystems GPP; MOD17A2H; validation; FLUXNET2015; global ecosystems





Author: Lunche Wang 1,†,* , Hongji Zhu 2,†,* , Aiwen Lin 2,* , Ling Zou 2, Wenmin Qin 2 and Qiyong Du 2

Source: http://mdpi.com/



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