Global observational diagnosis of soil moisture control on the land surface energy balance
Global observational diagnosis of soil moisture control on the land surface energy balance
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DOI：
10.1002/2016gl068178
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发表时间：
2016-03
影响因子：
5.2
通讯作者：
B. Gallego-Elvira;C. Taylor;P. Harris;D. Ghent;K. Veal;S. Folwell
中科院分区：
文献类型：
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作者：
B. Gallego-Elvira;C. Taylor;P. Harris;D. Ghent;K. Veal;S. Folwell
由于缺乏大规模观测，对地表能量收支在哪里以及在多大程度上受到土壤水分的制约的理解受到阻碍，这导致气候模型中的不确定性。在这里，我们提出了一种结合卫星观测陆地表面温度和降雨量的新方法。我们得出了一个相对升温速率(RWR)诊断，它是衡量在10天的干旱期间，陆地相对于上面的大气变暖的速度。在我们的旱季组合中，在60°S和60°N之间的陆地表面73%的升温速度快于大气，这表明水分胁迫条件，并增加了显热。由于空气动力学和水文特性的差异，较短的植被和裸露土壤的RWR高于高大、根部较深的植被。我们展示了RWR随前期降雨量的变化如何帮助识别主要非极地气候区不同的蒸发状况。
An understanding of where and how strongly the surface energy budget is constrained by soil moisture is hindered by a lack of large‐scale observations, and this contributes to uncertainty in climate models. Here we present a new approach combining satellite observations of land surface temperature and rainfall. We derive a Relative Warming Rate (RWR) diagnostic, which is a measure of how rapidly the land warms relative to the overlying atmosphere during 10 day dry spells. In our dry spell composites, 73% of the land surface between 60°S and 60°N warms faster than the atmosphere, indicating water‐stressed conditions, and increases in sensible heat. Higher RWRs are found for shorter vegetation and bare soil than for tall, deep‐rooted vegetation, due to differences in aerodynamic and hydrological properties. We show how the variation of RWR with antecedent rainfall helps to identify different evaporative regimes in the major nonpolar climate zones.