School of Water and Environment, Chang'an University, Xi'an, China.
Key Laboratory of Subsurface Hydrology and Ecological Effect in Arid Region, Ministry of Education, Chang'an University, Xi'an, China.
PLoS One. 2020 Nov 5;15(11):e0238709. doi: 10.1371/journal.pone.0238709. eCollection 2020.
Changes in precipitation patterns greatly impact regional drought/flood risk management and utilization of water resources. The main purpose of this paper was to investigate spatio-temporal variability of precipitation concentration in the transitional zone between Qinling Mountains (QDM), Guanzhong Plain (GZP) and the Loess Plateau (LPNS) in China, using monthly-scale precipitation concentration index (PCI) and daily-scale concentration index (CI) from daily rainfall records. The Mann-Kendall method was employed to illustrate the change in trend of PCI and CI, the Kriging interpolation method was adopted to measure spatial distribution, and the Wavelet transforms were used to explore their spatio-temporal correlation with the Arctic Oscillation (AO) & Western Pacific Subtropical High (WPSH) for revealing the potential attribution of precipitation concentration variation. Also, the regional implication of CI was investigated in the zone to provide local knowledge of the index application. Results showed that annual precipitation demonstrated a north-south increasing layered spatial distribution in the zone, representing a generally decreasing trend. The CI change generally exhibited a more significant decreasing trend than did PCI in LPNS and GZP due to AO slowly increasing over time, with a spatially weak layered or radial north-south decay, and an insignificant increasing trend in QDM impacted by the enhancing WPSH, with an obvious layered or radial spatial distribution. The spatiotemporal pattern of PCI variation represented similar characteristics in attribution with CI, but an inverse spatial distribution due to the phase difference (positive and negative effects) of AO and WPSH influencing seasonal precipitation. Regional analysis of CI showed that the CI value with over 0.62 indicated that approximately 80% of precipitation was contributed by 25% of the rainiest days in this zone. Fortunately, the area with this high CI has been getting smaller, implying a positive trend toward regional flash flood and debris flow control.
降水格局的变化极大地影响了区域干旱/洪涝风险管理和水资源利用。本文的主要目的是利用中国秦岭山脉（QDM）、关中平原（GZP）和黄土高原（LPNS）过渡带的月尺度降水集中指数（PCI）和日尺度降水集中指数（CI），研究降水集中的时空变化。采用Mann-Kendall 方法说明 PCI 和 CI 趋势变化，采用克里金插值方法测量空间分布，采用小波变换探讨其与北极涛动（AO）和西太平洋副热带高压（WPSH）的时空相关性，揭示降水集中变化的潜在归因。此外，还研究了 CI 在该区域的区域意义，为该指数的应用提供了局部知识。结果表明，该区域年降水量呈南北增加的层状空间分布，整体呈减少趋势。由于 AO 随时间的缓慢增加，CI 的变化趋势比 PCI 在 LPNS 和 GZP 中更为显著，其空间分布为弱层状或径向南北递减，而在受增强 WPSH 影响的 QDM 中呈不显著的增加趋势，呈明显的层状或径向空间分布。PCI 变化的时空格局与 CI 具有相似的归因特征，但由于 AO 和 WPSH 的相位差（正负效应）影响季节性降水，因此空间分布相反。CI 的区域分析表明，CI 值大于 0.62 表明该区域约 80%的降水是由 25%的降雨量最大的日子贡献的。幸运的是，具有高 CI 值的区域正在缩小，这意味着区域内的山洪和泥石流控制呈积极趋势。
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