Publications

Tang, Ronglin; Shao, Kun; Li, Zhao-Liang; Wu, Hua; Tang, Bo-Hui; Zhou, Guoqing; Zhang, Li (2015). Multiscale Validation of the 8-day MOD16 Evapotranspiration Product Using Flux Data Collected in China. IEEE JOURNAL OF SELECTED TOPICS IN APPLIED EARTH OBSERVATIONS AND REMOTE SENSING, 8(4), 1478-1486.

Abstract
Accurate estimates of terrestrial evapotranspiration (ET) are critical and significant to the field for modeling water and energy transfer between the land surface and atmosphere. This paper evaluates the 8-day MOD16 actual ET product using the ground-based eddy covariance (EC) system and large aperture scintillometer (LAS) measurements collected from 2008 to 2011 at seven sites in North and Northwest China. Overall, the 8-day MOD16 ET reproduces the temporal patterns of both the LAS and EC measurements but tends to underestimate and overestimate these measurements at high and low ET levels, respectively. It is also of limited use when surface is irrigated because under such condition significant underestimation is observed. Using the LAS measurements that also include a large source area does not generate a better agreement than using the EC measurements which comprise a small source area. The 8-day MOD16 ET averaged over 3 x 3 km(2) MODIS pixels agree better with both the EC and LAS measurements than that extracted at the 1 x 1 km2 MODIS pixel. For the EC validation, the relative bias and the relative root-mean-square error (RMSE) vary between 5% and -59% and between 35% and 120%, respectively, for the LAS validation, the relative bias and the relative RMSE vary between 6% and -69% and between 55% and 108%, respectively. The agreement between one site and another is not consistent and varies greatly. More validation work is recommended to testing the general applicability of the MOD16 ET product at a large number of sites worldwide.

DOI:
10.1109/JSTARS.2015.2420105

ISSN:
1939-1404