Remotely sensed land surface temperature- (LST-) dependent evapotranspiration (ET) models and vegetation index- (VI-) LST methods may not be suitable for ET estimation in energy-limited cold areas. In this study, the relationship of ET to LST was simulated using the process-based Simultaneous Heat and Water (SHAW) model for energy- and water-limited conditions in Mongolia,tounderstandthedifferencesinETprocessesunderthesetwolimitingconditionsindryandcoldclimates.Simulation resultsfromtheSHAWmodelalongwithgroundobservationaldatashowedthatETandLSThaveapositiverelationshipwhenair temperature(𝑇𝑎)islessthanorequaltothetemperature(𝑇tra)abovewhichplantstranspireandhaveanegativerelationshipwhen 𝑇 𝑎 is greater than 𝑇tra under the energy-limited condition. However, ET and LST maintain a negative relationship with changes in 𝑇𝑎 under the water-limited condition. The differences in the relationship between ET and LST under the energy-limited and water limitedconditionscouldbeattributedtoplanttranspirationandenergystorageinmoist/wateredsoilandplants.Thisstudy suggeststhatdifferentstrategiesshouldbeusedtoestimateETundertheenergy-limitedconditionindryandcoldclimates.
