Abstract: Evapotranspiration (ET) is the major process of Earth’s surface water and heat exchange, and has obvious spatial variation. The development and application of remote sensing technology make the regional estimation of ET realistic. This paper reviewed the research progress in the remote sensing regional ET estimation models, including single and two-layer models based on land surface energy balance, with the focus on the algorithm and characteristics of the Atmosphere-Land Exchange Inverse model (ALEXI) developed in recent years. To overcome the limitation of meteorological data, the ALEXI was coupled with Two-Source Energy Balance model (TSEB) and simplified atmospheric boundary layer model, and thereby, improved the estimation accuracy. Substantial studies showed that the ALEXI evaporative stress index (ESI) had strong capacity in regional drought monitoring. In order to give a better operational drought monitoring service, the combination of multi-source remote sensing data fusion technology, land surface data assimilation system, and remote sensing ET estimation models could be an important research field in the future.

Key words: Soil basal respiration potential, Urease, Invertase, Acid phosphomonoesterase, Tea bushes, Red soil