Thermodynamic limits of hydrologic cycling within the Earth system: concepts, estimates and implications
Thermodynamic limits of hydrologic cycling within the Earth system: concepts, estimates and implications
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DOI：
10.5194/hess-17-2873-2013
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发表时间：
2013-01-01
影响因子：
6.3
通讯作者：
Renner, M.
中科院分区：
文献类型：
--
作者：
Kleidon, A.;Renner, M.
水循环是能量转换和大气输送相结合的结果，热力学定律对两者都有限制。在这里，我们应用热力学推导出地球系统内水文循环强度的极限，以及塑造这些极限的属性和过程。我们建立了简单的模型，推导出蒸发和降水的极限与太阳辐射强迫的垂直和水平差异的解析表达式。这些限制来自一个基本的权衡，即更大的蒸发率降低了温度梯度，从而降低了大气运动的驱动力，使地面的潮湿空气与高空的干燥空气交换。因此，水文循环的限制反映了水文通量、运动和驱动梯度之间的强烈相互作用。尽管简单的模型，它们产生的水文循环的限制，在观测到的幅度内的估计，这表明全球水文循环接近其最大强度。我们关闭的讨论如何热力学限制可以提供一个更好的表征植被和人类活动与水文循环的相互作用。
The hydrologic cycle results from the combination of energy conversions and atmospheric transport, and the laws of thermodynamics set limits to both. Here, we apply thermodynamics to derive the limits of the strength of hydrologic cycling within the Earth system and about the properties and processes that shape these limits. We set up simple models to derive analytical expressions of the limits of evaporation and precipitation in relation to vertical and horizontal differences in solar radiative forcing. These limits result from a fundamental trade-off by which a greater evaporation rate reduces the temperature gradient and thus the driver for atmospheric motion that exchanges moistened air from the surface with the drier air aloft. The limits on hydrologic cycling thus reflect the strong interaction between the hydrologic flux, motion, and the driving gradient. Despite the simplicity of the models, they yield estimates for the limits of hydrologic cycling that are within the observed magnitude, suggesting that the global hydrologic cycle operates near its maximum strength. We close with a discussion of how thermodynamic limits can provide a better characterization of the interaction of vegetation and human activity with hydrologic cycling.