Moon Heewon, Guillod Benoit P, Gudmundsson Lukas, Seneviratne Sonia I
Institute for Atmospheric and Climate Science ETH Zurich Zurich Switzerland.
Institute for Environmental Decisions ETH Zurich Zurich Switzerland.
Geophys Res Lett. 2019 Feb 16;46(3):1861-1869. doi: 10.1029/2018GL080879. Epub 2019 Feb 14.
Soil moisture-precipitation feedbacks in a large ensemble of global climate model simulations are evaluated. A set of three metrics are used to assess the sensitivity of afternoon rainfall occurrence to morning soil moisture in terms of their spatial, temporal, and heterogeneity characteristics. Positive (negative) spatial feedback indicates that the afternoon rainfall occurs more frequently over wetter (drier) land surface than its surroundings. Positive (negative) temporal feedback indicates preference over temporally wetter (drier) conditions, and positive (negative) heterogeneity feedback indicates preference over more spatially heterogeneous (homogeneous) soil moisture conditions. We confirm previous results highlighting a dominantly positive spatial feedback in the models as opposed to observations. On average, models tend to agree better with observations for temporal and heterogeneity feedback characteristics, although intermodel variability is largest for these metrics. The collective influence of the three feedbacks suggests that they may lead to more localized precipitation persistence in models than in observations.
在大量全球气候模型模拟中评估了土壤湿度 - 降水反馈。使用一组三个指标，从空间、时间和非均匀性特征方面评估下午降雨发生对早晨土壤湿度的敏感性。正（负）空间反馈表明下午降雨在较湿润（干燥）的陆地表面比其周围环境更频繁发生。正（负）时间反馈表明对时间上较湿润（干燥）条件的偏好，而正（负）非均匀性反馈表明对空间上更不均匀（均匀）的土壤湿度条件的偏好。我们证实了先前的结果，突出了模型中占主导地位的正空间反馈，这与观测结果相反。平均而言，模型在时间和非均匀性反馈特征方面往往与观测结果更一致，尽管这些指标的模型间变异性最大。这三种反馈的综合影响表明，与观测相比，它们可能导致模型中的降水持续性更具局地性。
