The evapotranspiration (ET) from urban vegetation is recognized as an effective way to improve the urban thermal environment. However, the traditional ET measurement approaches, such as the sap flow method, are limited in providing urban ET for specific areas. Consequently, establishing quantitative relationship between cooling effects and ET becomes challenging, which is crucial for understanding the role of urban greenery in mitigating urban heat. To overcome this challenge, an estimation model based on the three-temperature (3T) model was developed for accurately estimating urban ET by employing a reference tree with accurate ET data. In contrast to the 3T model, this study proposed a new method (modified 3T model) that considers the influence of the three-dimensional crown structure on the energy balance. Additionally, it retains the advantage over traditional ET models by not requiring the calculation of resistance parameters. This reduces the impact of uncertainty in the estimated resistance parameters on the ET results. The modified 3T model was validated based on the sap flow method and Bowen ratio system, where the results indicated good agreement between the modified 3T model and measured ET data, with root mean square errors of 22.2 W·m−2 and 26.4 W·m−2, respectively. Furthermore, the absolute relative error of ET estimation was affected by energy-related factors, such as solar radiation, air temperature, and relative humidity. The modified 3T model exhibited low sensitivity to surface temperatures, where the average sensitivity coefficients were below ±0.15 from 0600 local time (LT) to 1700 LT. Considering the low accuracy of surface temperatures measured by infrared cameras (±2 °C), it would be beneficial to combine the modified 3T model with unmanned aerial vehicles and infrared remote sensing to measure urban ET.
CORE (COnnecting REpositories)
CORE (COnnecting REpositories)