Evaluation of GCOM-C ET_index Estimation Algorithm at a Lodgepole Pine Tree Open Forest in Idaho, USA

抄録

  This study attempted to evaluate the performance of the GCOM-C ET_index estimation algorithm at a lodgepole pine tree open forest in eastern Idaho, United States using a dataset provided by the Idaho EPSCoR program. As a limitation of the study, the energy balance closure problem in flux measurement, which is a typical problem in flux measurements by eddy covariance systems, prevented a robust, quantitative evaluation of the ET estimation accuracy. Under this limitation, the results indicated that the estimation algorithm overestimated ET in the conditions of the study area, especially during summer time. One possible reason for the overestimation was that the algorithm overestimated surface wetness over most of the year, except in winter. The results of this evaluation provide valuable information for future improvement of the estimation algorithm. Further investigation of the weather and flux conditions, including the use of additional data such as scintillometer-measured flux data, might reduce uncertainty in the measured flux data.