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<p>Reference evapotranspiration (ET₀) is a key indicator of atmospheric water demand and a fundamental component of hydroclimatic processes, particularly in climate sensitive regions such as the southwestern Amazon. Understanding the large-scale climatic drivers of ET₀ variability is essential for evaluating changes in evaporative demand under ongoing climate and environmental transformations. This study investigates the influence of major Pacific and Atlantic oceanic teleconnections on ET₀ variability in the state of Acre, Brazil, during 1982–2020. Monthly ET₀ estimates derived from surface meteorological observations were analyzed using an integrated framework combining trend detection, change point analysis, lagged correlation, composite analysis, seasonal assessment, and wavelet coherence, allowing the identification of long-term tendencies, regime shifts, and non-stationary relationships across multiple time scales. Results reveal a statistically significant upward trend in ET₀ of + 0.400&#xa0;mm year⁻¹ (<i>p</i> &lt; 0.001), indicating sustained intensification of atmospheric evaporative demand. A pronounced regime shift occurs around 2000, marking a transition toward higher ET₀ levels in recent decades. The analyses demonstrate a clear hierarchy of large-scale oceanic influences. Variability associated with the tropical Atlantic, particularly the Atlantic Multidecadal Oscillation and the Tropical North Atlantic, exerts the strongest, most immediate, and most persistent control on ET₀, with strengthened coupling after the late 1990s and marked non stationarity across time scales. In contrast, Pacific influences linked to ENSO are secondary and episodic, characterized by weaker correlations, delayed responses, and enhanced sensitivity to central Pacific anomalies represented by NINO4, consistent with El Niño Modoki type events. Atlantic dominance governs evapotranspiration.</p> Graphical abstract <p></p> <p>Reference evapotranspiration (ET₀) in southwestern Legal Amazon (Acre, Brazil) exhibits a significant long-term intensification from 1982 to 2020, marked by a positive trend of + 0.400&#xa0;mm year⁻¹ and a regime shift around 2000. Using an integrated framework of trend analysis, lagged correlations, composites, seasonal assessment, and wavelet coherence, this study reveals a clear hierarchy of oceanic controls on atmospheric water demand. Tropical Atlantic variability, particularly the Atlantic Multidecadal Oscillation (AMO) and the Tropical North Atlantic (TNA), emerges as the dominant and persistent driver of ET₀ variability, with strengthened coupling after the late 1990s. In contrast, Pacific influences associated with ENSO are secondary and episodic, characterized by delayed responses and a stronger sensitivity to central Pacific warming (NINO4; El Niño Modoki). The results highlight the leading role of Atlantic warming in modulating hydroclimatic demand over southwestern Amazonia.</p>

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Influence of Oceanic Teleconnections on Reference Evapotranspiration Variability in Southwestern Amazonia

  • 期刊论文

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  • 发表日期：

    2026年4月6日

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  • Helder José Farias da Silva,
  • Jório Bezerra Cabral Júnior,
  • Daniele Torres Rodrigues,
  • Jean Souza dos Reis,
  • Fabrício Daniel dos Santos Silva,
  • Rafaela Lisboa Costa,
  • Helber Barros Gomes,
  • Katyelle Ferreira da Silva Bezerra,
  • Dirceu Luis Herdies

摘要

Reference evapotranspiration (ET₀) is a key indicator of atmospheric water demand and a fundamental component of hydroclimatic processes, particularly in climate sensitive regions such as the southwestern Amazon. Understanding the large-scale climatic drivers of ET₀ variability is essential for evaluating changes in evaporative demand under ongoing climate and environmental transformations. This study investigates the influence of major Pacific and Atlantic oceanic teleconnections on ET₀ variability in the state of Acre, Brazil, during 1982–2020. Monthly ET₀ estimates derived from surface meteorological observations were analyzed using an integrated framework combining trend detection, change point analysis, lagged correlation, composite analysis, seasonal assessment, and wavelet coherence, allowing the identification of long-term tendencies, regime shifts, and non-stationary relationships across multiple time scales. Results reveal a statistically significant upward trend in ET₀ of + 0.400 mm year⁻¹ (p < 0.001), indicating sustained intensification of atmospheric evaporative demand. A pronounced regime shift occurs around 2000, marking a transition toward higher ET₀ levels in recent decades. The analyses demonstrate a clear hierarchy of large-scale oceanic influences. Variability associated with the tropical Atlantic, particularly the Atlantic Multidecadal Oscillation and the Tropical North Atlantic, exerts the strongest, most immediate, and most persistent control on ET₀, with strengthened coupling after the late 1990s and marked non stationarity across time scales. In contrast, Pacific influences linked to ENSO are secondary and episodic, characterized by weaker correlations, delayed responses, and enhanced sensitivity to central Pacific anomalies represented by NINO4, consistent with El Niño Modoki type events. Atlantic dominance governs evapotranspiration.

Graphical abstract

Reference evapotranspiration (ET₀) in southwestern Legal Amazon (Acre, Brazil) exhibits a significant long-term intensification from 1982 to 2020, marked by a positive trend of + 0.400 mm year⁻¹ and a regime shift around 2000. Using an integrated framework of trend analysis, lagged correlations, composites, seasonal assessment, and wavelet coherence, this study reveals a clear hierarchy of oceanic controls on atmospheric water demand. Tropical Atlantic variability, particularly the Atlantic Multidecadal Oscillation (AMO) and the Tropical North Atlantic (TNA), emerges as the dominant and persistent driver of ET₀ variability, with strengthened coupling after the late 1990s. In contrast, Pacific influences associated with ENSO are secondary and episodic, characterized by delayed responses and a stronger sensitivity to central Pacific warming (NINO4; El Niño Modoki). The results highlight the leading role of Atlantic warming in modulating hydroclimatic demand over southwestern Amazonia.