Biased estimates of the isotope ratios of steady‐state evaporation from the assumption of equilibrium between vapour and precipitation
Biased estimates of the isotope ratios of steady‐state evaporation from the assumption of equilibrium between vapour and precipitation
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根据水蒸气和降水之间的平衡假设对稳态蒸发同位素比的估计存在偏差
DOI：
10.1002/hyp.13531
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发表时间：
2019
影响因子：
3.2
通讯作者：
Bowen, Gabriel J.
中科院分区：
文献类型：
--
作者：
Fiorella, Richard P.;West, Jason B.;Bowen, Gabriel J.
稳定水同位素比率可作为树叶、土壤和湖泊等材料中环境过程的示踪剂进行测量。这些档案中的水可能会经历蒸发，从而与蒸发水和周围大气之间的湿度梯度和同位素比率成比例地增加重同位素同位素的丰度。直到最近，大气的同位素比率一直难以测量，并且测量结果仍然很少。因此，采用了几种假设来估计大气水蒸气的同位素比率。也许陆地环境中最常用的假设是水蒸气与降水处于同位素平衡。我们使用大气环流模型（GCM）模拟的八元系综来评估这一假设，其中包括降水和蒸汽中同位素比率的显式计算。我们发现，在整个模型集合中，如果与年降水量处于平衡状态，重同位素体中的水蒸气消耗通常比预期的要少。大气蒸气的同位素比可能高于预期，因为降水同位素比是由有利于凝结的大气条件决定的，这不能反映降水事件之外的大气混合和平流过程。这种偏差对蒸发水同位素比的理论估计的影响与相对湿度成正比。因此，平衡假设对低纬度地区蒸发水的同位素比率给出了相对准确的估计，但在纬度增加时表现越来越差。蒸发水池的未来研究应包括大气同位素比率的测量或通过同位素启用的 GCM 模拟来限制潜在偏差。
Stable water isotope ratios are measured as a tracer of environmental processes in materials such as leaves, soils, and lakes. Water in these archives may experience evaporation, which increases the abundance of heavy isotopologues proportionally to the gradients in humidity and isotope ratio between the evaporating water and the surrounding atmosphere. The isotope ratio of the atmosphere has been difficult to measure until recently, and measurements remain scarce. As a result, several assumptions have been adopted to estimate isotope ratios of atmospheric water vapour. Perhaps the most commonly employed assumption in terrestrial environments is that water vapour is in isotopic equilibrium with precipitation. We evaluate this assumption using an eight‐member ensemble of general circulation model (GCM) simulations that include explicit calculation of isotope ratios in precipitation and vapour. We find that across the model ensemble, water vapour is typically less depleted in heavy isotopologues than expected if it were in equilibrium with annual precipitation. Atmospheric vapour likely possesses higher‐than‐expected isotope ratios because precipitation isotope ratios are determined by atmospheric conditions that favour condensation, which do not reflect atmospheric mixing and advection processes outside of precipitation events. The effect of this deviation on theoretical estimates of isotope ratios of evaporating waters scales with relative humidity. As a result, the equilibrium assumption gives relatively accurate estimates of the isotope ratios of evaporating waters in low latitudes but performs increasingly poorly at increasing latitudes. Future studies of evaporative water pools should include measurements of atmospheric isotope ratios or constrain potential bias with isotope‐enabled GCM simulations.
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亚马逊盆地中部的降水：贝伦和马瑙斯的降雨和大气湿度的同位素组成
DOI：
--
发表时间：
1983
期刊：
影响因子：
--
作者：
E. Matsui;E. Salati;M. N. Ribeiro;C. Reis;A. C. F. Tancredi;J. Gat
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J. Gat
影响因子：
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C. Risi;D. Noone;J. Worden;C. Frankenberg;G. Stiller;Michael T. Kiefer;B. Funke;K. Walker;P. Bernath;M. Schneider;D. Wunch;V. Sherlock;N. Deutscher;D. Griffith;P. Wennberg;K. Strong;D. Smale;E. Mahieu;S. Barthlott;F. Hase;O. García;J. Notholt;T. Warneke;G. Toon;D. Sayres;S. Bony;Jeonghoon Lee;D. Brown;R. Uemura;C. Sturm
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C. Risi;D. Noone;J. Worden;C. Frankenberg;G. Stiller;Michael T. Kiefer;B. Funke;K. Walker;P. Bernath;M. Schneider;D. Wunch;V. Sherlock;N. Deutscher;D. Griffith;P. Wennberg;K. Strong;D. Smale;E. Mahieu;S. Barthlott;F. Hase;O. García;J. Notholt;T. Warneke;G. Toon;D. Sayres;S. Bony;Jeonghoon Lee;D. Brown;R. Uemura;C. Sturm
1871-2011 年 ECHAM5-wiso 历史气候模型输出（T106 分辨率）
DOI：
--
发表时间：
2017
期刊：
影响因子：
--
作者：
N. Steiger
通讯作者：
N. Steiger
影响因子：
4.4
作者：
Fiorella, Richard P.;Poulsen, Christopher J.;Ehlers, Todd A.
通讯作者：
Ehlers, Todd A.
影响因子：
3.7
作者：
West JB;Sobek A;Ehleringer JR
通讯作者：
Ehleringer JR