Presentation Information
[U06-P01]An Operational Framework for Monitoring Agricultural Evapotranspiration in Taiwan Using Satellite Imagery and the SSEBop Model
*Cheng-Ru Chen1, Chi-Farn Chen1, Thanh-Son Nguyen1, Liang-Chien Chen1, Yao-Cheng Kuo1 (1.Center for Space and Remote Sensing Research, National Central University)
Keywords:
Agricultural Evapotranspiration,SSEBop Model,MODIS–Landsat Time-Series Fusion
Accurate estimation of evapotranspiration (ET) is critical for agricultural production in Taiwan, where crop yield is highly sensitive to water availability under a subtropical monsoon climate, complex topography, and intensive farming systems. Spatiotemporal variability in ET directly influences irrigation efficiency, crop growth, and yield stability, making operational ET monitoring an essential component for assessing agricultural water use and supporting sustainable food production. However, persistent cloud cover and heterogeneous field patterns present major challenges for satellite-based ET estimation in Taiwan. This study develops an operational framework to monitor agricultural ET in Taiwan using an eight-day temporal cycle over the period from 2024 to 2025. The approach integrates Moderate Resolution Imaging Spectroradiometer (MODIS) and Landsat time-series imagery to overcome the trade-off between temporal frequency and spatial resolution. MODIS provides high revisit observations, while Landsat supplies 30 m spatial detail required for field-scale agricultural analysis. Time-series fusion techniques, Spatial and Temporal Adaptive Reflectance Fusion Model (STARFM) are applied to generate continuous eight-day composite datasets of land surface temperature (LST) and vegetation-related surface properties, effectively reducing cloud-induced data gaps. Actual evapotranspiration (ETa) is estimated using the Operational Simplified Surface Energy Balance (SSEBop) model. The model derives the evapotranspiration fraction (ETf) from normalized LST based on hot and cold boundary conditions and converts ETf to ET a using reference evapotranspiration (ETo). Meteorological forcing for ETo is obtained from the ECMWF ERA5 reanalysis dataset, providing consistent fields of radiation, air temperature, humidity, and wind speed throughout the study period. Key SSEBop parameters, including Temperature Difference (dT) and maximum ET coefficients, are regionally adapted to reflect Taiwan's climatic and seasonal characteristics. The resulting eight-day ET products capture crop water use dynamics and seasonal variability at the field scale and can be aggregated to irrigation districts and river basins. This framework provides a robust and scalable solution for linking ET dynamics to agricultural productivity, supporting irrigation management, yield assessment, and climate-resilient agricultural planning in Taiwan.