Transport Dynamics of the Northeast Pacific In a Changing Climate

在过去的几十年里，东北太平洋（NEP）经历了巨大的气候变化，在2013-2019年期间发生了一系列破纪录的极端温度，例如2013- 2015年东北太平洋多年的海洋热浪，2015-16年强烈的厄尔尼诺Niño，以及最近正在进行的2019年阿拉斯加热浪。由此导致的阿拉斯加湾（GOA）和加州洋流系统（CCS）的温度和漩涡尺度海洋运输动力学（如跨海岸、沿海岸、上升流）的变化导致了巨大的生态系统影响，包括沿岸有害藻华、初级生产力低下、哺乳动物和鸟类大量死亡。尽管我们对大尺度太平洋变化的理解有所进展，但仍不清楚GOA和CCS的区域运输动态如何响应观测到的极端气候和NEP年代际气候变率趋势，以及在人为气候强迫下预计运输统计数据会发生什么变化。（Q1）过去几十年东北太平洋区域气候变化的放大如何影响加州和阿拉斯加湾环流系统的涡旋尺度运输动力学（如沿岸、跨岸、上升流）？（Q2）在最近的极端温度事件（2013-2019年）期间，控制区域海洋运输统计的太平洋大尺度驱动因素是什么？在历史长期变率（1950-2000年）的背景下，运输变化是否显著（例如极端）？（Q3）在人为强迫（2050-2100）下，预计东北太平洋与生态相关的运输统计数据将如何变化，这些变化与最近的极端事件（2013-2019）期间发生的变化是否一致？本研究的目的是确定和估计东北太平洋与生态相关的涡旋尺度输送动力学对（目标1）近期大尺度气候强迫（例如极端事件、趋势、年代际变率）的放大的响应，以及（目标2）从单个地球系统模式（ESMs）的大综合推断的人为气候变化预估变化，这些模式可以区分内部变率和强迫变率。将培养和指导两名女博士生。PI将在他正在进行的跨学科研究/领导活动中分享他在加州- lter， PICES和美国CLIVAR的研究。本研究生成的高分辨率区域气候集合档案将成为东北太平洋海洋研究界的独特资产。PI将与CCE-LTER团队合作，使模型输出可用于跨学科研究，并开发一套线性逆模型教程，以帮助海洋生态系统科学家应用该方法探索生态动力学。调查的方法和任务将包括：（T1）一个由10个成员组成的高分辨率区域耦合海洋-大气模式历史模拟（1950-2019），其中包含一个被动示踪运输模块，以缩小大尺度太平洋气候强迫对GOA和CCS区域运输动力学的影响；（T2）一组线性逆模型（LIMs），用于识别和量化从被动示踪剂推断出的大尺度驱动因素对生态相关区域运输统计的影响；（T3）使用SSP5-8.5或等效情景下单个esm（例如CESM， GFDL ESM2M）的大集合模拟作为LIM的输入，以研究在内部气候变率背景下，人为强迫如何预估影响目标运输统计。近期东北太平洋气候变化和生态系统同步的增加，以及2013- 2015年东北太平洋海洋热浪、2015-16年厄尔尼诺Niño强热浪、2019年阿拉斯加热浪等极端温度对生态和社会的影响，引起了人们对东北太平洋区域海洋学中自然和人为强迫作用的关注和质疑。长期以来，涡旋尺度的运输动力学（如沿岸、跨岸、上升流）一直被认为是海洋生态系统变化的关键驱动因素，但这些动力学对气候变化的响应尚不清楚。这项工作将有助于了解生态驱动因素的气候变化的近期趋势与长期历史变率和人为强迫之间的关系。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Over the last decades, the Northeast Pacific (NEP), has experienced dramatic changes in its climate with the occurrence of a sequence of record-breaking temperature extremes between 2013-2019, such as the multi-year 2013-15 Northeast Pacific marine heatwave, the strong 2015-16 El Niño, and more recently the ongoing 2019 Alaskan heatwave. The resulting changes in temperature and eddy-scale ocean transport dynamics (e.g. cross-shore, alongshore, upwelling) in the Gulf of Alaska (GOA) and California Current System (CCS) led to dramatic ecosystem impacts that include harmful algal blooms along the coasts, low primary productivity, massive die offs of mammals and birds. Despite advances in our understanding of the large-scale Pacific changes, it remains unclear how regional transport dynamics of the GOA and CCS are responding to the observed climate extremes and trends in decadal climate variability in the NEP, and what changes in transport statistics are expected under anthropogenic climate forcing. Key Questions: (Q1) How did the amplification of the regional climate variance in the Northeast Pacific over the last decades impact eddy-scale transport dynamics (e.g. alongshore, cross-shore, upwelling) in the California and Gulf of Alaska circulation systems? (Q2) What are the Pacific largescale drivers that control the regional ocean transport statistics during the recent temperature extremes (2013-2019), and are the changes in transport significant (e.g. an extreme) in the context of historical long-term variability (1950-2000)? (Q3) How are ecologically-relevant transport statistics in the Northeast Pacific expected to change under anthropogenic forcing (2050-2100), and are these changes consistent with what occurred during the recent extremes (2013-2019)? The goal of this research is to identify and estimate the response of ecologically-relevant eddyscale transport dynamics in the Northeast Pacific to (GOAL1) recent amplifications of large-scale climate forcing (e.g. extremes, trends, decadal variability), and (GOAL2) projected changes in anthropogenic climate change as inferred from large-ensemble of individual Earth System Models (ESMs) that allow to separate the internal vs forced variability. Two female Ph.D. students will be trained and mentored. The PI will share this research in his ongoing interdisciplinary research/leadership activities in the California-LTER, PICES, and US CLIVAR. The high-resolution regional climate ensemble archive generated in this study will be a unique asset to the marine research community in the Northeast Pacific. The PI will work with the CCE-LTER team to make the model output available for interdisciplinary studies and to develop a set of Linear Inverse Model tutorials to help marine ecosystem scientists apply this methodology to explore ecological dynamics.The approaches & TASKs of the investigation will include (T1) a 10-member ensemble of high-resolution regional coupled ocean-atmosphere model historical simulations of the Northeast Pacific (1950-2019) with a passive tracers transport module to downscale the impact of large-scale Pacific climate forcing on regional transport dynamics in the GOA and CCS, (T2) a set of Linear Inverse Models (LIMs) to identify and quantify the effects of large-scale drivers on ecologically-relevant regional transport statistics inferred from the passive tracers, (T3) the use of large ensemble simulations of individual ESMs (e.g. CESM, GFDL ESM2M) under the SSP5-8.5 or equivalent scenario as input to the LIM to investigate how anthropogenic forcing is projected to impact the targeted transport statistics in the context of internal climate variability. The recent increase in climate variance and ecosystem synchrony in the Northeast Pacific, together with the ecological and societal impacts of the temperatures extremes of the 2013-15 Northeast Pacific marine heatwave, the strong 2015-16 El Niño, 2019 Alaskan heatwave, raise concern and questions of the role of natural and anthropogenic forcing in the regional oceanography of the Northeast Pacific. Eddy-scale transport dynamics (e.g. alongshore, cross-shore, upwelling) have long been recognized as a key driver of marine ecosystem change, yet the response of these dynamics to a changing climate remains unclear. This work will provide understanding on how the recent trends in the climate variance of ecological drivers relates to long-term historical variability and to anthropogenic forcing.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.