研究使用了一个热力学系统框架，独立的观测数据表明，干湿地区地表温度的气候变化主要是通过辐射效应介导的。研究首次证明，感热和潜热的湍流通量受热力学和局地辐射调节的限制。这种限制来自于地面辐射加热做功，以维持湍流通量和维持对流边界层内垂直混合的能力。这意味着干燥地区减少蒸发的冷却被增加的感热通量和浮力所补偿，这与观测结果一致。
研究表明，干燥和潮湿地区的平均温度变化主要受云控制，云减少了太阳辐射对地表面的加热。利用卫星对多云和晴空条件进行观测，研究人员表示，云使潮湿地区的地表温度降温高达7K，而在干旱地区由于云的缺乏，这种效应并不存在。研究结论为，辐射和热力学限制是控制地表温度和湍流通量交换的主要控制因素，这使得在复杂的气候系统中观察到的气候模式突然变得简单起来。
研究人员表示，地表温度(LSTs)受辐射的强烈影响，但受湍流通量和水文循环的调节，因为大气(云)和地表(蒸发)中的水蒸气的存在会影响整个地区的温度。
附：英文原文
Title: Radiative controls by clouds and thermodynamics shape surface temperatures and turbulent fluxes over land
Author: Ghausi, Sarosh Alam, Tian, Yinglin, Zehe, Erwin, Kleidon, Axel
Issue&Volume: 2023-7-10
Abstract: Land surface temperatures (LSTs) are strongly shaped by radiation but are modulated by turbulent fluxes and hydrologic cycling as the presence of water vapor in the atmosphere (clouds) and at the surface (evaporation) affects temperatures across regions. Here, we used a thermodynamic systems framework forced with independent observations to show that the climatological variations in LSTs across dry and humid regions are mainly mediated through radiative effects. We first show that the turbulent fluxes of sensible and latent heat are constrained by thermodynamics and the local radiative conditions. This constraint arises from the ability of radiative heating at the surface to perform work to maintain turbulent fluxes and sustain vertical mixing within the convective boundary layer. This implies that reduced evaporative cooling in dry regions is then compensated for by an increased sensible heat flux and buoyancy, which is consistent with observations. We show that the mean temperature variation across dry and humid regions is mainly controlled by clouds that reduce surface heating by solar radiation. Using satellite observations for cloudy and clear-sky conditions, we show that clouds cool the land surface over humid regions by up to 7 K, while in arid regions, this effect is absent due to the lack of clouds. We conclude that radiation and thermodynamic limits are the primary controls on LSTs and turbulent flux exchange which leads to an emergent simplicity in the observed climatological patterns within the complex climate system.
DOI: 10.1073/pnas.2220400120
Source: https://www.pnas.org/doi/10.1073/pnas.2220400120