Department of Earth and Environmental Systems, Indiana State University, Terre Haute, 47809, IN, USA.
Department of Marine Sciences, University of Puerto Rico, Mayaguez, 00680, Puerto Rico, USA.
Nat Commun. 2020 Feb 5;11(1):716. doi: 10.1038/s41467-020-14490-y.
Many Holocene hydroclimate records show rainfall changes that vary with local orbital insolation. However, some tropical regions display rainfall evolution that differs from gradual precessional pacing, suggesting that direct rainfall forcing effects were predominantly driven by sea-surface temperature thresholds or inter-ocean temperature gradients. Here we present a 12,000 yr continuous U/Th-dated precipitation record from a Guatemalan speleothem showing that Central American rainfall increased within a 2000 yr period from a persistently dry state to an active convective regime at 9000 yr BP and has remained strong thereafter. Our data suggest that the Holocene evolution of Central American rainfall was driven by exceeding a temperature threshold in the nearby tropical oceans. The sensitivity of this region to slow changes in radiative forcing is thus strongly mediated by internal dynamics acting on much faster time scales.
许多全新世水文气候记录显示，降雨量的变化随当地轨道辐照度而变化。然而，一些热带地区的降雨演变不同于逐渐的岁差 pacing，这表明直接降雨强迫效应主要是由海面温度阈值或大洋间温度梯度驱动的。本文展示了来自危地马拉一处洞穴石笋的 12000 年连续 U/Th 定年降水记录，表明中美洲降雨量在 9000 年前从持续干燥状态增加到活跃的对流状态，此后一直保持强劲。我们的数据表明，中美洲降雨量的全新世演变是由附近热带海洋中温度阈值的超过驱动的。因此，该地区对辐射强迫缓慢变化的敏感性受到在更快时间尺度上起作用的内部动力学的强烈调节。
