Precipitation recycling is essential to sustaining regional ecosystems and water supplies, and it is impacted by land development and climate change. This is especially true in the tropics, where dense vegetation greatly influences recycling. Unfortunately, large-scale models of recycling often exhibit high uncertainty, complicating efforts to estimate recycling. Here, we examine how deuterium excess (d-excess), a stable-isotope quantity sensitive to recycling effects, acts as an observational proxy for recycling. While past studies have connected variability in d-excess to precipitation origins at local or regional scales, our study leverages >3000 precipitation isotope samples to quantitatively compare d-excess against three contemporary recycling models across the global tropics. Using rank-correlation, we find statistically significant agreement (\(\bar \tau = 0.52\) to \(0.70\)) between tropical d-excess and recycling that is strongly mediated by seasonal precipitation, vegetation density, and scale mismatch. Our results detail the complex relationship between d-excess and precipitation recycling, suggesting avenues for further investigation.

降水循环对维持区域生态系统和供水至关重要，它受到土地开发和气候变化的影响。在热带地区尤其如此，那里茂密的植被极大地影响了回收利用。不幸的是，大规模的回收模型通常表现出很高的不确定性，使估算回收的工作复杂化。在这里，我们研究了对回收效应敏感的稳定同位素量氘过量 (d-excess) 如何作为回收的观察代理。虽然过去的研究将 d-excess 的变异性与局部或区域尺度的降水起源联系起来，但我们的研究利用 >3000 降水同位素样本对 d-excess 与全球热带地区的三个当代循环模型进行了定量比较。使用秩相关，\(\bar \tau = 0.52\)到\(0.70\) ) 介于热带 d 过量和循环之间，后者由季节性降水、植被密度和规模不匹配强烈介导。我们的结果详细说明了 d 过量与降水循环之间的复杂关系，为进一步调查提供了途径。