Mechanisms behind early winter rainfall variability in the southwestern Cape, South Africa
Mechanisms behind early winter rainfall variability in the southwestern Cape, South Africa
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南非开普省西南部初冬降雨变化背后的机制
DOI：
10.1007/s00382-018-4571-y
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发表时间：
2018
期刊：
影响因子：
4.6
通讯作者：
Mahlalela P
中科院分区：
文献类型：
--
作者：
Mahlalela P
南非西南部地区是南部非洲唯一一个主要在南部冬季（4月至9月）获得全年降雨量的地区。2015-2017年，该国这一地区经历了极端干旱的条件，导致开普敦市出现严重的水资源短缺。在这项研究中，重点放在了解初冬期（4月至5月）的贡献，在南非西南部的潮湿和干燥的年份。这一时期特别令人感兴趣，因为它在最近的干旱中发挥了关键作用，以前没有关于这一季节的工作，而且气候变化预测冬季雨季的持续时间可能缩短。近几十年来，初冬容易出现干燥状况，最近记录的六个最干燥的4月至5月中有五个发生在2000年之后。特别是干燥的初冬往往与较弱的副热带急流，较少的水分流入该领域和更稳定的大气有关。结果表明，尽管南方环形模态与初冬降水之间存在中等程度的相关关系，但与整个冬季相比，南方环形模态的相关性并不强。对CMIP 5模型的分析发现，预测将南非冬季降雨区描述为未来（2040-2060年）初冬干燥条件的可能性增加。然而，这仍然是一个挑战，这些模型合理地捕捉在南非冬季降雨的开始。
The southwest region of South Africa is the only part of southern Africa that predominantly receives its total annual rainfall during the austral winter months (April–September). In 2015–2017, this part of the country experienced extreme dry conditions which led to the severe water shortages experienced in the city of Cape Town. In this study, focused is placed on understanding the contribution of the early winter period (April–May) to wet and dry years in the southwestern part of South Africa. This period is of particular interest given its key role in the recent drought, the lack of previous work on this season, and climate change projections that the winter rainy season may shorten in duration. The early winter is found to be prone to dry conditions in recent decades, such that five of the six driest April–May in recent record have occurred after the year 2000. The dry early winters in particular tend to be associated with a weaker subtropical jet, less moisture flowing into the domain and a more stable atmosphere. It is found that although there is a moderate relationship between the Southern Annular Mode and early winter rainfall, it is not as strong as that compared to the full winter period. An analysis of CMIP5 models find that the projections portray the winter rainfall region in South Africa as being exposed to an increased likelihood of early winter dry conditions into the future (2040–2060). However, it remains a challenge for these models to reasonably capture the onset of winter rainfall in South Africa.
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DOI：
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发表时间：
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期刊：
影响因子：
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DOI：
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发表时间：
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期刊：
影响因子：
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影响因子：
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