Downgradient Energy Transport and the Atmospheric Circulation

地球的大气层就像一台热机，把能量从过剩的地区输送到不足的地区。尽管大气在全球范围内具有非常不同的环流模式，但热输运随纬度的变化非常平稳。新兴的研究表明，这种热传输似乎被很好地描述为一种扩散过程，它取决于赤道到极点的能量对比。如果是这样，这样一个简单的概念可能为观测到的气候学和气候变化（过去和未来）的许多方面提供一个基本的解释。本研究解决了以下问题：(1)尽管大气运动非常复杂，为什么这个能量传输的概念模型如此有效；(2)该模型解释过去气候状态的水文和全球温度分布以及大气成分的能力。将热传输描述为扩散过程在科学中是如此基础，以至于这项研究有可能显著提高公众对气候科学的理解。除了指导一名年轻的研究科学家外，研究人员还将培训一名研究生，并让本科生大量参与研究活动。具体来说，研究人员试图了解随着气候状态的变化，大气环流如何调整以保持近乎线性的下梯度能量输送。通过观测，他们将确定经向焓梯度和大气热输运之间的近线性关系如何作为空间和时间的函数出现。此外，他们将进行数值实验，改变动力传输机制（例如，改变地球的自转速度和地形），以探索近线性关系的极限。最后，研究人员将分析现有的古气候模拟，以及精心定位的新模拟，以评估这种简单的热传输模型如何很好地表征过去的气候。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

The earth’s atmosphere operates as a heat engine, transporting energy from regions of surplus to regions of deficit. The heat transport varies remarkably smoothly with latitude despite the atmosphere having very different circulation patterns across the globe. Emerging research suggests that this heat transport appears to be well-described as a diffusive process that depends on the equator-to-pole energy contrast. If so, such a simple concept may offer a fundamental explanation for many aspects of the observed climatology and climate change (past and future). This research addresses: (i) why this conceptual model of energy transport works so well despite the highly complex atmospheric motion and (ii) the model’s ability to explain the hydrology and global distribution of temperature and atmospheric constituents of past climate states. The description of heat transport as a diffusive process is so fundamental in science that this research has the potential to significantly improve the public understanding of climate science. In addition to mentoring a young research scientist, the researchers will train a graduate student and heavily involve undergraduates in research activities.Specifically, the researchers seek to understand how the atmospheric circulation adjusts to maintain a nearly linear downgradient energy transport as the climate state changes. Using observations, they will determine how the near-linear relationship between the meridional enthalpy gradient and the atmospheric heat transport emerges as a function of space and time. Furthermore, they will perform numerical experiments that vary the dynamical transport mechanisms (e.g., changing the Earth’s rotation rate and orography) to probe the limits of the near-linear relationship. Finally, the researchers will analyze existing paleoclimate simulations, as well as carefully targeted new simulations, to evaluate how well this simple heat transport model characterizes past climates.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.