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首页> 外文期刊>Climatic Change >Changes in the low flow regime over the eastern United States (1962-2011): variability, trends, and attributions
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Changes in the low flow regime over the eastern United States (1962-2011): variability, trends, and attributions

机译：美国东部（1962-2011年）低流量状态的变化：变异性，趋势和归因

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We examine trends and variability in low flows over the eastern U.S. (S. Carolina to Maine) and their attribution in a changing climate. We select 149 out of 4878 USGS stations over the eastern U.S., taking into account data availability and minimal direct management. Annual 7-day low flows (Q7) are computed from the series of daily streamflow records for 1962-2011 and compared to an antecedent precipitation (AP) index calculated over the corresponding basin for each station. In general, a north-south (increasing-decreasing) dipole pattern in low flow trends is associated with trends in AP. The exception is in the southern part of the study area including Virginia and the Carolinas, where moderate increasing trends in AP may have been offset by water withdrawals and increasing potential evapotranspiration (PET) as driven by increasing temperature and vapor pressure deficit. A principal component analysis (PCA) of Q7 and AP indicates that the North Atlantic Oscillation (NAO) and Pacific North America (PNA) pattern show statistically significant correlations for Q7 at 1 and 2 month lead time, respectively, via large-scale pressure patterns. Our findings suggest that the inter-annual variability of low flows has increased due to significant anti-correlation between the NAO and PNA during recent decades, and the future risk of low flow extremes may be further enhanced with temperature driven increases in PET and persistence of the multi-decadal relationship between NAO and PNA.
机译：我们研究了美国东部地区（南卡罗来纳州到缅因州）低流量的趋势和变化及其在气候变化中的归因。考虑到数据的可用性和最少的直接管理，我们在美国东部的4878个USGS站点中选择149个。根据1962-2011年的每日流量记录，计算年度7天的低流量（Q7），并将其与每个台站在相应盆地上计算的前期降水（AP）指数进行比较。通常，低流量趋势中的南北向（递增-递减）偶极子模式与AP趋势相关。例外情况是研究区域的南部，包括弗吉尼亚州和卡罗来纳州，在这些地区，由于温度和蒸气压差的增加，取水量和潜在蒸散量（PET）的增加可能抵消了AP适度增加的趋势。 Q7和AP的主成分分析（PCA）表明，北大西洋涛动（NAO）和北美洲太平洋（PNA）模式分别通过大气压模式显示了在Q7提前期为1和2个月时的统计学显着相关性。 。我们的发现表明，由于近几十年来NAO和PNA之间存在显着的反相关性，低流量的年际变化有所增加，并且随着温度的升高，PET的持续存在和持久性的增强，未来低流量极端事件的风险可能会进一步增加。 NAO和PNA之间的多年代关系。

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