Empirical evidence of contrasting soil moisture–precipitation feedbacks across the United States
Empirical evidence of contrasting soil moisture–precipitation feedbacks across the United States
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DOI：
10.1126/science.aaa7185
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发表时间：
2016-05
期刊：
影响因子：
56.9
通讯作者：
S. Tuttle;G. Salvucci
中科院分区：
文献类型：
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作者：
S. Tuttle;G. Salvucci
降雨对降雨的影响土壤湿度在一定程度上受过去降雨的控制，可影响未来大面积降雨的可能性。这是因为土壤中的水分有助于确定阳光如何转化为潜热(蒸发)和显热(这会增加上面的空气温度)。Tuttle和Salucci使用了10多年来为毗邻的美国收集的数据来研究这种关系。土壤水分和降雨量之间的反馈在美国西部总体上是正的，而在东部则是负的。这种地区性依赖可能是干旱程度大范围差异的结果。科学，本期第825页过去的降雨量会影响未来大面积降雨的概率。土壤湿度影响源自地表的热量和水分通量，从而改变大气湿度和温度分布。然而，关于这如何影响降水倾向，经验研究和模型研究意见不一，主要是因为很难确定因果关系。我们使用格兰杰因果关系，通过遥感土壤湿度和基于雨量的观测，来估计土壤湿度和美国邻近地区后续降水发生之间的关系。剔除每日持续性、降水季节和年际变化的潜在混杂效应后，我们发现土壤湿度异常对降雨概率的影响超过38%，中位数因子为13%。这种反馈在西部总体上是积极的，在东部是负面的，这表明对地区干旱的依赖。
The effects of rainfall on rainfall Soil moisture, which is controlled in part by past rainfall, can affect the probability of future rainfall over large areas. This is because the water contained in soils helps determine how sunlight is converted into latent heat (evaporation) and sensible heat (which increases overlying air temperatures). Tuttle and Salvucci used data collected for the contiguous United States over 10 years to study this relationship. The feedback between soil moisture and rainfall is generally positive in the western United States but negative in the east. This regional dependence could be a function of large-scale differences in aridity. Science, this issue p. 825 Past rainfall can affect the probability of future rainfall over large areas. Soil moisture influences fluxes of heat and moisture originating at the land surface, thus altering atmospheric humidity and temperature profiles. However, empirical and modeling studies disagree on how this affects the propensity for precipitation, mainly owing to the difficulty in establishing causality. We use Granger causality to estimate the relationship between soil moisture and occurrence of subsequent precipitation over the contiguous United States using remotely sensed soil moisture and gauge-based precipitation observations. After removing potential confounding effects of daily persistence, and seasonal and interannual variability in precipitation, we find that soil moisture anomalies significantly influence rainfall probabilities over 38% of the area with a median factor of 13%. The feedback is generally positive in the west and negative in the east, suggesting dependence on regional aridity.