Observation‐Driven Characterization of Soil Moisture‐Precipitation Interactions in the Central United States
Observation‐Driven Characterization of Soil Moisture‐Precipitation Interactions in the Central United States
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DOI：
10.1029/2022jd037934
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发表时间：
2023-06
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影响因子：
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通讯作者：
T. Ford;Joshua W. H. Steiner;Bridgette Mason;S. Quiring
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作者：
T. Ford;Joshua W. H. Steiner;Bridgette Mason;S. Quiring
土壤水分反馈启动，增强或抑制对流的发生和降水是区域水文气候学的重要组成部分。然而，众所周知，土壤水分反馈及其运作过程在模型环境之外的观察和研究是非常具有挑战性的。在这项研究中，我们结合联合收割机的气候评估事件频率为基础的测量土壤水分-降水耦合在美国中部的一个过程为基础的分析机制，湿和干土壤反馈可能在该地区运作。我们使用的雷暴观测雷达算法，以确定对流开始的位置，规避使用降水积累作为对流开始的代理的问题。结果显示，在美国中部，包括表现出湿土和干土反馈迹象的地区，土壤水分-降水耦合的气候标志和强度存在显著的空间变异性。在反馈信号最强的区域内，我们发现土壤水分和地表热通量的分配之间始终存在强耦合，地表热通量特别是感热通量和行星边界层高度的日变化之间存在强耦合。在评估的所有三个区域中，基于过程的指标证实了湿和/或干土壤反馈导致对流启动的可能性。
Soil moisture feedbacks that initiate, enhance, or suppress convection initiation and precipitation are important components of regional hydroclimatology. However, soil moisture feedbacks and the processes through which they operate are notoriously challenging to observe and study outside of model environments. In this study, we combine a climatological assessment of event frequency‐based measurements of soil moisture‐precipitation coupling in the central United States with a process‐based analysis of the mechanisms by which wet‐ and dry‐soil feedbacks may operate in the region. We use the Thunderstorm Observation by Radar algorithm to identify the location of convection initiation, circumventing the issue of using precipitation accumulation as a proxy for convection initiation. Results show substantial spatial variability in the climatological sign and strength of soil moisture‐precipitation coupling in the central United States, including regions that exhibit signs of both wet‐ and dry‐soil feedbacks. Within the regions with the strongest feedback signals, we find consistently strong coupling between soil moisture and the partitioning of surface heat flux, and strong coupling between surface heat flux—particularly sensible heat flux—and diurnal change in planetary boundary layer height. In all three regions assessed, the process‐based metrics confirmed the potential of wet‐ and/or dry‐soil feedbacks leading to convection initiation.