P2C2: Hydroclimatic response of the tropical Pacific to past changes in mean state: Observations and synthesis

P2C2：热带太平洋对过去平均状态变化的水文气候响应：观测与综合

• 批准号: 1606764
• 负责人: Michael Evans
• 金额: $ 14.1万
• 依托单位: University of Maryland, College Park
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2016
• 资助国家: 美国
• 起止时间: 2016-08-01 至 2019-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1606764&HistoricalAwards=false
• 关键词: P2C2; Hydroclimatic; response; tropical; Pacific

How will El Niño events change as the climate changes? There is currently no consensus on the answer to this question from climate change projections for the 21st century. Yet even small changes in El Niño event strength, duration or frequency have significant effects, both in the US and internationally, on water resources, wildfires, agriculture and ecosystems. This project will contribute new observations and analysis of El Niño/Southern Oscillation (ENSO) activity during two past time intervals for which there are very few data from the tropical Pacific, yet for which the global climate is thought to have been relatively warm and relatively cold, respectively. Results will be compared to climate simulations for the same periods, so that we can better understand if, how and why global climate change can cause changes in El Niño activity. The project will also provide mentored, international, collaborative, and multidisciplinary training for a PhD student and an undergraduate researcher, including educational, outreach and dissemination activities. It will contribute inputs for modeling the interactions between people, fisheries and climate in a location and region with a rich archaeological history of pre-modern settlement, voyaging and exploration. These studies, which are beyond the scope of this project, may ultimately help us understand how societies have and may adapt to past and future climate change.Specifically, paired oxygen isotope and Sr/Ca data series will be developed from existing and diagenetically screened coral samples dating to the Little Ice Age (LIA) and Medieval Climate Anomaly (MCA) time windows from Aitutaki, southern Cook Islands (18.85S, 159.79W). Preliminary analysis suggests interannual variations in present day (PD) coral oxygen isotopic composition from the region primarily reflect sea surface salinity (SSS) variability resulting from changes in the position and strength of the South Pacific Convergence Zone associated with ENSO activity. In conjunction with other hydroclimatic and oceanographic paleoclimate data available for these time windows and the PD, the research team will test whether there were differences in interannual event amplitude and recurrence interval in the LIA and MCA relative to the PD. The team will compare the results to those obtained from similarly sampled, PMIP3-compliant physical climate simulations with both complete and single external radiative forcings. Comparison of observations and simulations, within the context of their uncertainties, will be used to assess if and the extent to which the observed hydroclimatic response is forced or unforced, and by what mechanisms.

随着气候变化，厄尔尼诺事件将如何变化？目前，从21世纪的气候变化项目中对这个问题的答案尚无共识。然而，即使是厄尔尼诺事件强度，持续时间或频率的小变化，在美国和国际上，对水资源，野火，农业和生态系统的影响都具有重大影响。该项目将在两个过去的时间间隔内对厄尔尼诺/南部振荡（ENSO）活动进行新的观察和分析，而热带太平洋的数据很少，但人们认为全球气候被认为是相对温暖且相对寒冷的。结果将与同一时期的气候模拟进行比较，以便我们可以更好地理解，全球气候变化是否会导致厄尔尼诺活动的变化。该项目还将为博士生和本科研究人员提供指导，国际，协作和多学科培训，包括教育，外展和传播活动。它将为在一个地点和地区的人们，渔业和气候之间的相互作用建模，并具有丰富的档案前，航行和勘探的历史。这些研究超出了该项目的范围，最终可能会帮助我们了解社会的发展和未来的气候变化。具体来说，将从现有且可透析的核心样本中开发成对的氧同位素和SR/CA数据系列，该样本可追溯到小冰河时代（LIA）和中世纪的气候Anomal（MCA）（MCA）（MCA 5 159.79W）。初步分析表明，来自该区域的珊瑚氧同位素组成在当今的年际变化反映了与ENSO活动相关的南太平洋收敛区的位置和强度变化导致的海面盐度（SSS）变异性。与这些时间窗口和PD可用的其他氢化气候和海洋气候数据一起，研究团队将测试LIA和MCA相对于PD，在年际事件放大器和复发间隔中是否存在差异。该团队将将结果与从类似采样的符合PMIP3符合的物理气候模拟和单个外部辐射强迫符合的结果进行比较。在其不确定性的背景下，观察和模拟的比较将用于评估观察到的水下气候反应的强制或不强制的程度，以及通过什么机制。