Stacking Ensemble Learning for Daily Potential Evapotranspiration using Limited Climate Data
摘要
Potential evapotranspiration (ET₀) is a key component of hydrological and ecological processes, yet its reliable estimation remains challenging in data-scarce regions. This study develops a stacking ensemble framework that integrates Transformer, Informer, and FEDformer models to improve daily ET₀ estimation in the Songliao Basin, Northeast China, using limited meteorological inputs. The proposed model employs Hargreaves–Samani–based potential evapotranspiration (HS ET₀), together with daily minimum and maximum air temperatures (Tmin and Tmax) as model inputs. Ground-based ET₀ calculated using the FAO-56 Penman–Monteith method is used for model training, validation, and testing. Results show that the stacking ensemble consistently outperforms individual base models and achieves a reduction in RMSE of 10.22%~10.32% comparing with the previous best-performing machine learning models, including Multilayer Perceptron (MLP), Convolutional Neural Network (CNN), Random Forest (RF), Support Vector Machine (SVM) and Long Short-Term Memory (LSTM) networks. SHAP-based sensitivity analysis indicates that HS ET₀ accounts for 56.96%~70.76% of the total mean absolute SHAP value, highlighting its dominant contribution to ET₀ prediction under limited data conditions. Overall, the proposed framework provides a robust and practical solution for daily ET₀ estimation when complete meteorological observations are unavailable.