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Decadal Regime Shifts in the Pacific Ocean: Mechanisms, Hydroclimatic Imprints, and Predictability

太平洋的年代际变化：机制、水文气候印记和可预测性

基本信息

批准号：
2101214
负责人：
Jason Smerdon
金额：
$ 87.14万
依托单位：
Columbia University
依托单位国家：
美国
项目类别：
Standard Grant
财政年份：
2021
资助国家：
美国
起止时间：
2021-09-01 至 2024-08-31
项目状态：
已结题

来源：
https://www.nsf.gov/awardsearch/showAward?AWD_ID=2101214&HistoricalAwards=false
关键词：
Decadal Regime Shifts Pacific Ocean

项目摘要

A map of the difference in Pacific sea surface temperature (SST) between two decades might show a wedge-shaped region of relatively warm sea surface temperatures (SSTs) extending west and toward the equator from the coasts of North and South America, covering much of the tropical Pacific and flanked by cold SSTs in the higher latitudes of both hemispheres. This pattern and its negative, with a wedge of colder SSTs spanning the tropical Pacific, account for a large fraction of Pacific decadal SST variability, referred to as PDV. The PDV pattern is of interest due to its association with prolonged periods of drier and wetter conditions around the world. In particular more precipitation is found over the western and central US in decades featuring the warm Pacific wedge while the cold wedge favors drought. The association of warmer with wetter and cooler with drier is also found in South America, as might be expected given the equatorial symmetry of the wedge, and model simulations in which the PDV pattern is imposed can reproduce the wetter and drier conditions over the Americas. The PDV pattern has attracted considerable attention but our understanding of it is limited by the length of the observational record for SSTs, which goes back roughly a century and a half and thus only captures a handful of events.Work under this award extends our understanding of the PDV pattern and its connections to continental hydroclimate using climate reconstructions for the last millennium based on tree rings and other proxy data. These include drought atlases for North America (The North American Drought Atlas, or NADA), Monsoon Asia (MADA), South American (SADA), and Europe and North Africa (the Old World Drought Atlas), among others, as well as the Paleo-Hydrodynamics Data Assimilation (PHYDA) and Last Millennium Reanalysis (LMR) products. These proxy-based datasets are complemented by analysis of simulations from the Paleoclimate Model Intercomparision Project (PMIP4) and the Community Earth System Model Last Millennium Ensemble (CESM LME). One question to be addressed is the extent to which the behavior of the PDV pattern is characterized by abrupt "regime shifts" between its warm and cold phases. Abrupt shifts are a notable feature of the PDV pattern in the 20th century but gradual transitions might be more common if a longer period is examined. Another question is whether the PDV warming and cooling were as pronounced in earlier centuries as in the 20th century, and whether PDV impacts on continental hydroclimate were as pronounced. The research also considers the extent to which the PDV pattern is predictable, a question which is pursued through additional model simulations including initialized hindcast simulations from the Decadal Climate Prediction Project.The work has broader impacts due to the societal and ecological impacts of prolonged pluvials and droughs. Given the similar PDV impacts over North and South America the project builds research connections to South America by hosting scientists from Argentina and Chile and convening a week-long workshop offering remote participation to a an online audience at several South American universities. The project also hosts a website for the dissemination of results. Project participants conduct a variety of education and outreach activities including presentations at the American Museum of Natural History, the Columbia Youth Summit, and local public schools. In addition, the project supports a graduate student, thereby supporting workforce development in this research area.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

20年间太平洋海表温度（SST）差异的地图可能会显示一个相对温暖的海表温度（SST）楔形区域，从北美和南美海岸向西向赤道延伸，覆盖了热带太平洋的大部分地区，两侧是两个半球高纬度的冷SST。这种模式和它的负面，与跨越热带太平洋的较冷的SST楔形，占太平洋年代际SST变率的很大一部分，称为PDV。 PDV模式由于其与世界各地较长时间的干燥和湿润条件相关联而受到关注。特别是在美国西部和中部发现了更多的降水在几十年的特点是温暖的太平洋楔，而冷楔有利于干旱。在南美洲也发现了温暖与潮湿和凉爽与干燥的联系，这可能是由于楔形的赤道对称性所预期的，并且强加PDV模式的模式模拟可以再现美洲上空的潮湿和干燥条件。 PDV模式已经引起了相当大的关注，但我们对它的理解是有限的SST的观测记录的长度，这可以追溯到大约一个世纪半，因此只捕获了少数事件。在这个奖项下的工作扩展了我们的理解PDV模式及其连接到大陆水文气候的气候重建的基础上，在过去的千年树木年轮和其他代理数据。其中包括北美干旱地图集（北美干旱地图集，或NADA），亚洲季风（MADA），南美（SADA），欧洲和北非（旧世界干旱地图集），以及古流体动力学数据同化（PHYDA）和最后千年再分析（LMR）产品。这些基于代理的数据集的补充分析模拟从古气候模型相互比较项目（PMIP 4）和社区地球系统模型最后千年Encourage（CESM LME）。要解决的一个问题是在何种程度上的PDV模式的行为的特点是突然的“政权转移”之间的温暖和寒冷的阶段。突变是20世纪PDV模式的一个显著特征，但如果考察一个较长的时期，则逐渐过渡可能更为常见。另一个问题是，PDV变暖和变冷在前几个世纪是否像世纪一样明显，以及PDV对大陆水文气候的影响是否同样明显。该研究还考虑了PDV模式可预测的程度，这是一个通过额外的模型模拟，包括初始化的十年期气候预测项目的后报模拟追求的问题。由于长期的多雨和干旱的社会和生态影响，这项工作具有更广泛的影响。鉴于PDV对北美和南美的影响相似，该项目通过接待来自阿根廷和智利的科学家并召开为期一周的研讨会，为几所南美大学的在线观众提供远程参与，建立了与南美的研究联系。该项目还设有一个网站，用于传播成果。项目参与者开展各种教育和推广活动，包括在美国自然历史博物馆、哥伦比亚青年峰会和当地公立学校做演讲。此外，该项目还支持一名研究生，从而支持该研究领域的劳动力发展。该奖项反映了NSF的法定使命，并通过使用基金会的智力价值和更广泛的影响审查标准进行评估，被认为值得支持。