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Quantifying variability of the El Nino Southern Oscillation on adaptation-relevant time scales using a novel palaeodata-modelling approach

使用新颖的古数据建模方法量化厄尔尼诺南方涛动在适应相关时间尺度上的变化

基本信息

批准号：
NE/H009957/1
负责人：
Alexander Tudhope
金额：
$ 67.18万
依托单位：
University of Edinburgh
依托单位国家：
英国
项目类别：
Research Grant
财政年份：
2010
资助国家：
英国
起止时间：
2010 至无数据
项目状态：
已结题

来源：
https://gtr.ukri.org/projects?ref=NE%2FH009957%2F1
关键词：
Quantifying variability El Nino Southern

项目摘要

The research proposed here aims to help us understand year-to-year variations in climate around the world. This includes the occurrence of floods and droughts, of heat waves and cold spells. To do this, we are going to examine the largest source of year-to-year climate variability on Earth, namely, El Niño. The El Niño is a warm ocean current that appears off the coast of NW South America every 3-5 years, and it is a result of a much larger scale phenomenon involving changes to the winds, rainfall, temperature and ocean currents across the whole of the tropical Pacific. The larger scale phenomenon is known as the El Niño Southern Oscillation, a name which reflects the fact that it involves a natural cycle in the circulation of both the atmosphere and the surface ocean and how they interact. Although we know that ENSO originates in the tropical Pacific, it has near world-wide impacts because of the way it affects the circulation of the atmosphere, and hence the winds and transport of moisture from the tropics to the extra-tropics. Floods and droughts and changed incidence of storminess from El Niño directly affect the lives and livelihoods of well over a billion people, and major El Niño events are associated with tens of thousands of human deaths, billions of pounds of damage, and devastation to some natural ecosystems such as coral reefs. Even Europe experiences changed weather patterns associated with ENSO! Although we now understand quite well the basic mechanisms behind the ENSO cycle, some major questions remain. In particular, we do not understand why some El Niño events are much stronger than others, why some decades show much stronger El Niño activity, or how ENSO will respond to climate change. To help answer some of these questions, we will reconstruct changes in ENSO over the past 5,000 years by analysing growth rings in the skeletons of old dead ('fossil') corals that lived in the Galápagos. The Galápagos Islands experience extreme changes in weather associated with El Niño (warmer and wetter during events), and these changes are recorded in the chemistry of the skeletons of corals living in the surrounding ocean. Some of these corals live for up to a hundred years, or longer, laying down layers of skeleton a bit like tree rings. We will collect cores through old dead corals, including some that lived thousands of years ago. Then, by analysing the chemistry of their growth bands we will be able to reconstruct the changes in climate, and ENSO, that the corals experienced during their life time. By combining the records from many such corals we will build up a picture of the natural variability in ENSO, helping us see how often major events occurred, and how much decade-to-decade variability in ENSO occurred. These coral records can let us reconstruct the history of past changes in ENSO, but on their own they do not help us to understand the causes of the changes. Were they due to changes in the sun's radiation? Or due to the cooling effects of major volcanic eruptions? Or were they simply random variations that we should expect without any sort of trigger? To answer these questions, we need to use climate models. The same models that we now use to predict future climate can be used to research changes in ENSO. In our work, we will use the most up-to-date climate models to see if they can correctly replicate the observed changes in ENSO over the past few thousand years as defined by our coral records. We can also see what the effects are of changing volcanic eruptions, solar radiation and greenhouse gases in these models. By comparing the model results with the coral records we will get a better understanding of the nature and causes of changes in ENSO, and the skill of the models at predicting this. In this way we will make a significant contribution to helping predict the likely range of ENSO-related climate events for the coming decades.

这里提出的研究旨在帮助我们了解世界各地气候的逐年变化。这包括洪水和干旱、热浪和寒潮的发生。为此，我们将研究地球上逐年气候变化的最大来源，即厄尔尼诺现象。厄尔尼诺现象是南美洲西北部海岸每3-5年出现一次的温暖洋流，是整个热带太平洋风、降雨、温度和洋流变化的更大规模现象的结果。规模更大的现象被称为厄尔尼诺南方涛动，这个名称反映了这样一个事实：它涉及大气和海洋表面循环的自然循环以及它们如何相互作用。尽管我们知道 ENSO 起源于热带太平洋，但由于它影响大气环流的方式，从而影响风和水分从热带到热带外的输送，因此它的影响几乎遍及全球。厄尔尼诺现象造成的洪水和干旱以及暴风雨发生率的变化直接影响了超过十亿人的生活和生计，重大厄尔尼诺事件导致数万人死亡、数十亿磅的损失以及珊瑚礁等一些自然生态系统的破坏。甚至欧洲也经历了与 ENSO 相关的天气模式的变化！尽管我们现在已经非常了解 ENSO 循环背后的基本机制，但仍然存在一些主要问题。特别是，我们不明白为什么一些厄尔尼诺事件比其他事件强得多，为什么有些几十年显示出更强的厄尔尼诺活动，或者ENSO将如何应对气候变化。为了帮助回答其中一些问题，我们将通过分析生活在加拉帕戈斯群岛的老死珊瑚（“化石”）骨骼中的生长环来重建 ENSO 在过去 5000 年的变化。加拉帕戈斯群岛经历了与厄尔尼诺现象相关的极端天气变化（事件期间变暖和湿润），这些变化被记录在周围海洋珊瑚骨骼的化学成分中。其中一些珊瑚的寿命长达一百年，甚至更长，形成一层层的骨骼，有点像树木的年轮。我们将通过老死珊瑚收集核心，包括一些生活在数千年前的珊瑚。然后，通过分析其生长带的化学成分，我们将能够重建珊瑚在其一生中经历的气候变化和 ENSO。通过结合许多此类珊瑚的记录，我们将绘制出 ENSO 自然变化的图景，帮助我们了解重大事件发生的频率以及 ENSO 发生的十年到十年的变化程度。这些珊瑚记录可以让我们重建ENSO过去变化的历史，但它们本身并不能帮助我们理解变化的原因。它们是由于太阳辐射的变化造成的吗？还是由于大型火山喷发的冷却效应？或者它们只是我们应该在没有任何触发因素的情况下预期的随机变化？为了回答这些问题，我们需要使用气候模型。我们现在用来预测未来气候的模型也可以用来研究 ENSO 的变化。在我们的工作中，我们将使用最新的气候模型来看看它们是否能够正确复制我们的珊瑚记录所定义的过去几千年中观测到的 ENSO 变化。我们还可以在这些模型中看到火山喷发、太阳辐射和温室气体变化的影响。通过将模型结果与珊瑚记录进行比较，我们将更好地了解 ENSO 变化的性质和原因，以及模型预测这一情况的技巧。通过这种方式，我们将为帮助预测未来几十年与 ENSO 相关的气候事件的可能范围做出重大贡献。