Jiang, Y; Zhang, JH; Xu, XD; Dong, ZX (2013). A GPP assimilation model for the southeastern Tibetan Plateau based on CO2 eddy covariance flux tower and remote sensing data. INTERNATIONAL JOURNAL OF APPLIED EARTH OBSERVATION AND GEOINFORMATION, 23, 213-225.
The gross primary production (GPP) at individual CO2 eddy covariance flux tower sites (GPP(TOWER)) in Dali (DL), Wenjiang (WJ) and Linzhi (LZ) around the southeastern Tibetan Plateau were determined by the net ecosystem exchange of CO2 (NEE) and ecosystem respiration (R-e). The satellite remote sensing-VPM model estimates of GPP values (GPP(MODIS)) used the satellite-derived 8-day surface reflectance product (MOD09A1), including satellite-derived enhanced vegetation index (EVI) and land surface water index (LSWI). In this paper, we assembled a subset of flux tower data at these three sites to calibrate and test satellite-VPM model estimated GPP(MODIS), and introduced the satellite data and site-level environmental factors to develop four new assimilation models. The new assimilation models' estimates of GPP values were compared with GPP(MODIS) and GPP(TOWER), and the final optimum model among the four assimilation models was determined and used to calibrate GPP(MODIS). The results showed that GPP(MODIS) had similar temporal variations to the GPP(TOWER), but GPP(MODIS) were commonly higher in absolute magnitude than GPP(TOWER) with relative error (RE) about 58.85%. While, the assimilation models' estimates of GPP values (GPP(MODEL)) were much more closer to GPP(TOWER) with RE approximately 6.98%, indicating that the capacity of the simulation in the new assimilation model was greatly improved, the R-2 and root mean square error (RMSE) of the new assimilation model were 0.57-4.90% higher and 0.74-2.47 g C m(-2) s(-1) lower than those of the GPP(MODIS), respectively. The assimilation model was used to predicted GPP dynamics around the Tibetan Plateau and showed a reliable result compared with other researches. This study demonstrated the potential of the new assimilation model for estimating GPP around the Tibetan Plateau and the performances of site-level biophysical parameters in related to satellite-VPM model GPP. Crown Copyright (C) 2012 Published by Elsevier B.V. All rights reserved.