Evaluation of the GCOM-C global ETsub(index) estimation algorithm
2016
Tasumi, M. (University of Miyazaki, Miyazaki (Japan). Faculty of Agriculture, Department of Forest and Environmental Sciences) | Moriyama, M. | Hirakawa, K. | Fujii, A.
This paper presents the application results of the Global Change Observation Mission-Climate (GCOM-C) global ETsub(index) estimation algorithm to the entire globe over the seven years from 2001 to 2007 using MODIS daily thermal observation data as a substitute for GCOM-C thermal observation data. The GCOM-C global ETsub(index) estimation algorithm was developed to automatically provide global ETsub(index) information for the Global Change Observation Mission (GCOM) of the Japan Aerospace Exploration Agency (JAXA). The ETsub(index) maps resulting from this study were compared with global precipitation, Koeppen's climate classification, and forest distribution maps in order to investigate the general correspondence between the ETsub(index) and climate/ecosystem distributions. The estimated ETsub(index) was confirmed to be in general agreement with the distributions of climate and forest at the global and continental scales and at annual and seasonal timescales. The resultant global evapotranspiration (ET) maps were evaluated using point-measured precipitation for 199 locations worldwide and measured ET data in Mongolia. The relationship between precipitation and ET supported the adequacy of the ET estimation method for annual timescales. A monthly comparison of the ETsub(index) with precipitation implied that the algorithm is functional in summer but nonfunctional in winter under some conditions. An accuracy assessment of the algorithm using actual ET measurement data from Mongolia indicated that the algorithm showed good performance at annual timescales. The error in the 4-year average of estimated ET was equivalent to 12% of the actual ET or 0.7% of the reference ET.
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