Operational Global Actual Evapotranspiration: Development, Evaluation and Dissemination.

Area of Science:

• Hydrology
• Remote Sensing
• Agricultural Science

Background:

• Satellite-derived actual evapotranspiration (ETa) is crucial for water management and agricultural applications.
• The Operational Simplified Surface Energy Balance (SSEBop) model is vital for the USGS Famine Early Warning System Network (FEWS NET) drought monitoring.
• Global implementation of SSEBop requires integration with satellite and weather data.

Purpose of the Study:

• To present the global implementation of the SSEBop model using MODIS land surface temperature and global weather data.
• To evaluate the performance of the global SSEBop ETa data against eddy covariance flux tower measurements.
• To assess the suitability of SSEBop ETa for water budget studies and drought monitoring.

Main Methods:

• Utilized Aqua satellite's MODIS land surface temperature data.
• Incorporated global gridded weather datasets.
• Validated SSEBop ETa outputs using 12 eddy covariance (EC) flux tower sites across six continents.

Main Results:

• The SSEBop model demonstrated reasonable performance, capturing ETa seasonality with correlation coefficients up to 0.87.
• Identified regional biases in the modeled ETa magnitude, necessitating further investigation.
• ETa anomalies showed high reliability for drought monitoring without modification.

Conclusions:

• The global SSEBop ETa is a valuable tool for drought monitoring and early warning systems.
• Absolute ETa magnitudes require bias correction for precise water budget applications.
• Freely available ETa products support diverse water resource management needs.