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Study Region Guangxi, China Study Focus Climate warming intensifies global water scarcity and drought risks, underscoring the need to understand reference evapotranspiration (ET 0 ). However, the combined effects of meteorological factors and large scale climate variability (LSCV) on ET 0 across time-frequency domains remain unclear. Based on meteorological data and LSCV data spanning 1960–2024, this study investigates the spatiotemporal trends and drivers of ET 0 in Guangxi, China, employing Theil–Sen median trend analysis, Mann–Kendall testing, wavelet transform coherence, multiple wavelet coherence, and generalized additive models. New Hydrological Insights for the region The results showed that although ET 0 trends shifted around 1997, an overall decline occurred, with the most significant fluctuations in central Guangxi. Meteorological factors outweighed LSCV in influence. Sunshine duration (SSD), alone or combined with maximum temperature（T max ）and wind speed, was the primary meteorological driver. Key LSCV drivers included the North Pacific Oscillation index (NP), both individually and combined with Pacific Decadal Oscillation index and Niño 3.4 index. The hybrid combination of SSD and the Atlantic Multidecadal Oscillation index (AMO) was the most significant dual-factor driver. Threshold effects were identified: exceeding specific thresholds in T max , AMO, or NP resulted in significantly higher ET 0 . These insights enhance the mechanistic understanding of ET 0 variability and aid in improving prediction models and regional water resource management.
Fang et al. (Mon,) studied this question.