权益分类	功能权益	普通用户	{{item.name}}会员
{{category.name}}	{{benefitItem.name}}

Fingerprinting 'El Nino Costero': a unique opportunity to document the signature of an extreme flood event in northern Peru

“厄尔尼诺科斯特罗”指纹识别：记录秘鲁北部极端洪水事件特征的独特机会

基本信息

批准号：
NE/R004528/1
负责人：
Andrew Henderson
金额：
$ 6.68万
依托单位：
Newcastle University
依托单位国家：
英国
项目类别：
Research Grant
财政年份：
2017
资助国家：
英国
起止时间：
2017 至无数据
项目状态：
已结题

来源：
https://gtr.ukri.org/projects?ref=NE%2FR004528%2F1
关键词：
Fingerprinting El Nino Costero unique

项目摘要

The northern coast of Peru has been experiencing anomalously warm (4-5C) sea surface temperatures (SST). These high SSTs have produced intense and prolonged rainfall that has resulted in extensive flooding, and on the 26th March 2017, the Rio Piura in northern Peru burst its banks leading to loss of life, displacement of people and damaged infrastructure. Peru is intimately linked to the El Niño-Southern Oscillation (ENSO): fishermen first identified El Niño in the late 19th Century off the north coast of Peru. The phenomenon driving this current acute rainfall event has been dubbed 'El Niño Costero' or Coastal El Niño, but is not El Niño per se as it is not being driven by anomalous SSTs in the central Pacific (Niño 3.4), which generally defines the onset of El Niño. Rather it represents more local (Niño1+2) El Niño-like conditions last known to have occurred in 1925, which is considered the most intense flooding of the 20th Century. Despite Peru's preparedness for the global El Niño in 2016, the country appears to be overwhelmed by the sudden shift from La Niña drought to the intense rainfall of El Niño Costero, suggesting this type of locally driven El Niño event has hitherto been overlooked. It is essential to establish a record of El Niño Costero alongside ENSO, especially as the 1925 event was the most extreme on record. If local SSTs cause El Niño-like conditions and play an important part in climate dynamics in northern Peru, but have so far been overlooked, then we don't have a full understanding of tropical Pacific climate change. Critical to understanding equatorial Pacific climate change are records of extreme flood events that reflect El Niño-type behavior, and in particular how El Niño Costero fits within the wider climate picture. This proposal is based on a unique opportunity to quantify and determine the dynamics and evolution of a large magnitude flood, and to use its sedimentary signature, coupled to climatological data over the last 120 years, to unequivocally fingerprint and calibrate past El Niño-type events in recent lake sediments. We will (a) undertake a geophysical survey of lakes in the Rio Piura catchment that act as repositories of flood-waters and sediments, and we will identify modern flood sediments and determine their depth and extent; (b) recover and survey surface sediments related to flooding to characterize their flood signature using grain size, geochemistry and mineral magnetics; (c) recover and date short sediment cores from our survey lakes and directly compare the flood signature of the 2017 El Niño Costero to the 1925 event, as well as putting it in the context of 20th Century ENSO variability. Our study will provide a framework for reconstructing El Niño-related flood events from lake sediments over the recent past in northern Peru, but has the potential to establish a much longer-term (Holocene and older) history of all El Niño variability in the region.

秘鲁北部海岸一直在经历异常温暖(4-5摄氏度)的海洋表面温度(SST)。这些高SST造成了强烈和持续的降雨，导致大范围洪灾，2017年3月26日，秘鲁北部的里奥皮乌拉河决堤，造成生命损失、人员流离失所和基础设施受损。秘鲁与厄尔尼诺-南方涛动(ENSO)密切相关：19世纪末，渔民在秘鲁北海岸附近首次发现厄尔尼诺现象。这一现象被称为“厄尔尼诺-科斯特罗”或“海岸厄尔尼诺”，但并不是厄尔尼诺现象本身，因为它不是由太平洋中部异常的海温(尼诺3.4)驱动的，后者通常定义了厄尔尼诺现象的开始。相反，它代表了更局部的(尼诺1+2)厄尔尼诺现象，上一次发生在1925年，这被认为是20世纪最严重的洪水。尽管秘鲁为2016年全球厄尔尼诺现象做好了准备，但该国似乎被从拉尼娜干旱到厄尔尼诺·科斯特罗强降雨的突然转变所淹没，这表明这种由当地驱动的厄尔尼诺事件迄今一直被忽视。与ENSO一起建立厄尔尼诺-科斯特罗的记录是至关重要的，特别是因为1925年的事件是有记录以来最极端的。如果当地的海温导致了类似厄尔尼诺现象的情况，并在秘鲁北部的气候动态中发挥了重要作用，但到目前为止却被忽视了，那么我们对热带太平洋气候变化的了解还不够充分。了解赤道太平洋气候变化的关键是极端洪水事件的记录，这些记录反映了厄尔尼诺现象，特别是厄尔尼诺现象如何与更广泛的气候图景相适应。这一建议的依据是一个独特的机会，可以量化和确定大规模洪水的动态和演变，并利用其沉积特征，结合过去120年的气候学数据，明确识别和校准最近湖泊沉积物中过去的厄尔尼诺类型事件。我们将(A)对作为洪水和沉积物储存库的里约皮乌拉流域的湖泊进行地球物理勘探，并将查明现代洪水沉积物，确定其深度和范围；(B)恢复并调查与洪水有关的表层沉积物，利用粒度、地球化学和矿物磁学确定其洪水特征；(C)从我们调查的湖泊中恢复短沉积物岩心，并确定其年代，将2017年厄尔尼诺-科斯特罗事件与1925年事件的洪水特征进行直接比较，并将其置于20世纪ENSO多变性的背景下。我们的研究将为从秘鲁北部最近过去的湖泊沉积物中重建与厄尔尼诺有关的洪水事件提供一个框架，但有可能建立该区域所有厄尔尼诺变异性的更长期(全新世和更老的)历史。