Thermodynamic constraint on the depth of the global tropospheric circulation
Thermodynamic constraint on the depth of the global tropospheric circulation
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DOI：
10.1073/pnas.1620493114
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发表时间：
2017-06
期刊：
影响因子：
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通讯作者：
D. Thompson;S. Bony;Ying Li
中科院分区：
文献类型：
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作者：
D. Thompson;S. Bony;Ying Li
本研究探讨了气候科学中的两个基本问题：(1)控制对流层深度的物理因素；(2)云对气候变化的响应。以前的研究认为，热带铁砧温度受到水汽基本热力学性质的强烈限制。在这里，我们认为相同的基本热力学性质强烈地限制了对流层的深度、高云的温度和全球大尺度动力学的振幅。结果表明，与热带高空云相关的正气候反馈也在温带地区起作用，并且随着气候系统变暖，对流层顶部在全球范围内应保持大致相同的温度。对流层是大气的一个区域，其特点是静态稳定性低，强烈的非绝热混合和云中广泛的凝聚加热。以往的研究认为，在热带地区，对流层混合和云的上界受到饱和水汽压随高度迅速下降的限制，因此在晴空地区水汽的辐射冷却。在这里，作者认为相同的基本物理在限制全球对流层混合的垂直结构、对流层顶温度和云顶温度方面起着关键作用。本文认为，水汽的辐射冷却在控制温带纬度大尺度动力学的深度和幅度方面起着重要作用。
Significance The study explores two fundamental problems in climate science: (i) The physical factors that govern the depth of the troposphere, and (ii) the response of clouds to climate change. Previous research has argued that tropical anvil temperatures are strongly constrained by the fundamental thermodynamic properties of water vapor. Here we argue that the same basic thermodynamic properties strongly constrain the depth of the troposphere, the temperature of high clouds, and the amplitude of large-scale dynamics throughout the globe. The results suggest that the positive climate feedbacks associated with tropical high clouds also operate in the extratropics, and that the top of the troposphere should remain at roughly the same temperature throughout the globe as the climate system warms. The troposphere is the region of the atmosphere characterized by low static stability, vigorous diabatic mixing, and widespread condensational heating in clouds. Previous research has argued that in the tropics, the upper bound on tropospheric mixing and clouds is constrained by the rapid decrease with height of the saturation water vapor pressure and hence radiative cooling by water vapor in clear-sky regions. Here the authors contend that the same basic physics play a key role in constraining the vertical structure of tropospheric mixing, tropopause temperature, and cloud-top temperature throughout the globe. It is argued that radiative cooling by water vapor plays an important role in governing the depth and amplitude of large-scale dynamics at extratropical latitudes.