Multi-annual droughts in the English Lowlands: a review of their characteristics and climate drivers in the winter half-year
Multi-annual droughts in the English Lowlands: a review of their characteristics and climate drivers in the winter half-year
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DOI：
10.5194/hess-19-2353-2015
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发表时间：
2015-01-01
影响因子：
6.3
通讯作者：
Wallace, E.
中科院分区：
文献类型：
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作者：
Folland, C. K.;Hannaford, J.;Wallace, E.
英国低地位于英国东南部，是一个相对干燥、人口稠密的地区，这里的水资源使用非常密集。因此，该地区部分地区水资源紧张，面临越来越大的水资源压力。该地区严重依赖地下水，特别容易受到主要与冬季干燥有关的长期、多年干旱的影响。尽管存在这种脆弱性，但人们对该地区多年干旱的大气驱动因素了解甚少，这是制定适当的干旱管理战略，包括监测和预警系统的障碍。为了促进我们的理解，我们评估了冬季半年（10月至3月）已知的主要气候驱动因素及其与该地区多年干旱的可能关系。我们利用各种气象和水文数据集描述了1910年以来英国低地的历史多年干旱事件。利用整个区域的网格化降水序列识别多年干旱，并利用区域尺度河流和地下水时间序列的标准化降水指数（SPI）、标准化河流流量指数（SSI）和标准化地下水位指数（SGI）进行细化。我们探索了一系列潜在的气候驱动因子与冬季半年英国低地降水、河流流量和地下水位指标之间的联系。驱动或强迫因素包括厄尔尼诺-南方涛动（ENSO）、北大西洋三极海表温度（SST）模式、准两年一次涛动（QBO）、太阳和火山强迫以及大西洋多年代际涛动（AMO）。正如预期的那样，在历史记录中，没有一个单一的驱动因素能令人信服地解释任何多年干旱的发生。然而，我们首次证明了拉尼娜事件与英国低地一些主要的多年干旱事件的冬季降水不足之间的联系。我们还显示了ENSO与用于河流流量和地下水位的干旱指标之间的显著（尽管相对较弱）联系。我们还表明，上面列出的其他一些驱动因素可能会影响英国低地的降雨。最后，我们为未来的研究工作指明了方向。
The English Lowlands is a relatively dry, densely populated region in the south-east of the UK in which water is used intensively. Consequently, parts of the region are water-stressed and face growing water resource pressures. The region is heavily dependent on groundwater and particularly vulnerable to long, multi-annual droughts primarily associated with dry winters. Despite this vulnerability, the atmospheric drivers of multi-annual droughts in the region are poorly understood, an obstacle to developing appropriate drought management strategies, including monitoring and early warning systems. To advance our understanding, we assess known key climate drivers in the winter half-year (October-March) and their likely relationships with multi-annual droughts in the region. We characterise historic multi-annual drought episodes back to 1910 for the English Lowlands using various meteorological and hydrological data sets. Multi-annual droughts are identified using a gridded precipitation series for the entire region, and refined using the Standardized Precipitation Index (SPI), Standardized Streamflow Index (SSI) and Standardized Groundwater level Index (SGI) applied to regional-scale river flow and groundwater time series. We explore linkages between a range of potential climatic driving factors and precipitation, river flow and groundwater level indicators in the English Lowlands for the winter half-year. The drivers or forcings include El Nino-Southern Oscillation (ENSO), the North Atlantic tripole sea surface temperature (SST) pattern, the Quasi-Biennial Oscillation (QBO), solar and volcanic forcing and the Atlantic Multi-decadal Oscillation (AMO). As expected, no single driver convincingly explains the occurrence of any multi-annual drought in the historical record. However, we demonstrate, for the first time, an association between La Nina episodes and winter rainfall deficits in some major multi-annual drought episodes in the English Lowlands. We also show significant (albeit relatively weak) links between ENSO and drought indicators applied to river flow and groundwater levels. We also show that some of the other drivers listed above are likely to influence English Lowlands rainfall. We conclude by signposting a direction for this future research effort.