Impacts of the North Atlantic Subtropical High on Daily Summer Precipitation over the Conterminous United States
Impacts of the North Atlantic Subtropical High on Daily Summer Precipitation over the Conterminous United States
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DOI：
10.1175/jhm-d-20-0242.1
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发表时间：
2021-07
影响因子：
3.8
通讯作者：
E. Zorzetto;Laifang Li
中科院分区：
文献类型：
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作者：
E. Zorzetto;Laifang Li
北大西洋副热带高压（NASH）西脊通过调节从海洋到邻近陆地的水汽通量，显著影响美国本土（CONUS）夏季总降水。然而，它对美国大陆上每日降雨事件的频率和强度的影响仍然不清楚。在这里，我们引入贝叶斯统计模型来研究NASH西脊位置对日尺度夏季降水关键统计数据的影响，包括降雨事件的强度，降水发生的概率和极值的概率。这些统计量在描述极端潮湿天气（例如，洪水的可能性）和极端干旱。通过将该模型应用于覆盖整个CONUS的历史雨量计记录（1948-2019），我们发现NASH的西部脊影响了CONUS扩展区域的降雨频率和降雨强度分布。特别是，我们发现NASH脊也调制极端降雨的频率，特别是在东南部和上中西部的部分地区。我们的分析强调了包括NASH西部山脊位置作为水文应用的关键统计降雨特性的预测的重要性。这一结果是特别相关的预测未来的变化，每日降雨量制度在美国本土的基础上，预测加强的NASH在气候变暖。
By modulating the moisture flux from ocean to adjacent land, the North Atlantic Subtropical High (NASH) western ridge significantly influences summer-season total precipitation over the Conterminous United States (CONUS). However, its influence on the frequency and intensity of daily rainfall events over the CONUS remains unclear. Here we introduce a Bayesian statistical model to investigate the impacts of the NASH western ridge position on key statistics of daily-scale summer precipitation, including the intensity of rainfall events, the probability of precipitation occurrence, and the probability of extreme values. These statistical quantities play a key role in characterizing both the impact of wet extremes (e.g., the probability of floods) and dry extremes. By applying this model to historical rain gauge records (1948-2019) covering the entire CONUS, we find that the western ridge of the NASH influences the frequency of rainfall as well as the distribution of rainfall intensities over extended areas of the CONUS. In particular, we find that the NASH ridge also modulates the frequency of extreme rainfall, especially that over part of the Southeast and upper Midwest. Our analysis underlines the importance of including the NASH western ridge position as a predictor for key statistical rainfall properties to be used for hydrological applications. This result is especially relevant for projecting future changes in daily rainfall regimes over the CONUS based on the predicted strengthening of the NASH in a warming climate.