Collaborative Research: Characterizing Northern Hemisphere Atmospheric Variability from Central American Wind Gap-Induced Upwelling

中美洲马德雷山脉沿线有三个位置足够低，可以让风从大西洋进入太平洋。最北端的风口是“特万特佩克风口”(沿着墨西哥西南海岸)。这些当地已知的风(这里只是Tehuantepec Gap风)主要在冬季推动墨西哥湾凉爽、营养丰富的水的强烈上升，此时北美上空的高气压在Tehuantepec地峡建立了压力梯度。尽管Tehuantepec Gap风作为一种大西洋-太平洋遥相关具有潜在的重要性，但在快速和全球气候变化的背景下，没有人试图预测这些风对区域气候动态变化的反应。研究人员建议将过去上升流的气候记录(来自过去30.000年的沉积放射性碳)和模式模拟结合起来，以描述北大西洋的大气动力学过程，并检查这些风对上游因素的敏感性以及这种盆地间耦合的“下游”影响。在该项目的方法框架和假设检验中提出了一种新的大西洋-太平洋海洋-大气反馈机制，特万特佩克缺口风和大气Rossby波在其中发挥核心作用。这一合作项目将支持两名早期职业科学家，以及加州大学欧文分校(一家拉美裔服务机构和美洲太平洋岛民原住民服务机构)本科生的教育和科学培训。研究人员将继续参与他们学院扩大参与的努力，包括大气、海洋和冰冻圈科学(国家科学基金2150262)的ATOC REU，该项目主要从拉美裔服务机构招聘，向学生介绍数据科学和地球科学研究。此外，作为该项目的一部分，将制定一项关注地球气候长期变化的课程计划，并通过加州外展项目中的环境气候变化和扫盲项目进行试点，并发布在一个开放的国家气候教育学在线资源库(称为“气候主题”)中。特万特佩克湾是描述连接太平洋和大西洋部门的“上游”大气过程的理想地点，因为马德雷山脉的显著缺口迫使低层风通过特万特佩克地峡流向太平洋，推动当地更深、更低的放射性碳水上升到表面。初步模式结果和沉积物岩心测量利用了这种风与放射性碳的关系，为过去23,000年来北半球的大气动力学提供了宝贵的约束。以前对当代气候变异性的研究以及对模型和观测产品的初步检查表明，北美上空较高的大气压力与墨西哥湾较高的近地表气压有关，从而导致更强的特万特佩克风。这里建议的项目-包括新的沉积物替代测量、模型(古气候GCM)和数据产品检验，以及正向模拟-旨在发现特万特佩克空隙风力在古气候时间尺度上变化背后的驱动机制，这将为冰川-间冰期大气动力学提供关键的新约束，以及对热带太平洋海面温度和流域间水汽通量的控制。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

There are three locations along the Central American Sierra Madre mountains that are low enough to allow winds to pass from the Atlantic to the Pacific Ocean. The northernmost of these wind gaps is the ‘Tehuantepec Gap’ (along the southwest coast of Mexico). These locally known winds (here simply Tehuantepec Gap Winds) drive intense upwelling of cool, nutrient-rich water in the Gulf primarily in the winter when high atmospheric pressures over North America establish a pressure gradient across the Isthmus of Tehuantepec. Despite the potential importance of the Tehuantepec Gap Winds as an Atlantic-Pacific teleconnection, there has been no attempt to predict the response of these winds to changes in regional climate dynamics in the context of rapid and global climate change. The researchers suggest to combine past climate records of upwelling (from sedimentary radiocarbon over the last 30.000 years) and model simulations to characterize atmospheric dynamical processes over the North Atlantic, and to examine both the sensitivity of these winds to ‘upstream’ factors as well as the ‘downstream’ implications of this inter-basin coupling. A novel Atlantic-Pacific Ocean-atmosphere feedback mechanism is suggesting in the methodological framework and hypothesis testing of this project in which the Tehuantepec Gap Winds and atmospheric Rossby waves play a central role. This collaborative project will support two early career scientists, and the education and scientific training of undergraduate students at UC Irvine (both a Hispanic Serving Institution and Native American Pacific Islander-Serving Institution). The researchers will continue engagement in their institution’ broadening participation efforts, including ATOC REU in Atmospheric, Oceanic, and Cryospheric Sciences (NSF 2150262), a program that primarily recruits from Hispanic Serving Institutions to introduce students to data science and geoscience research. Additionally, a lesson plan focused on long-term variations in Earth’s climate will be developed as part of this project and piloted through Environmental Climate Change and Literacy Projects in California’s outreach programs and posted in an openly available national online repository for climate pedagogy (called “Subject to Climate”).The Gulf of Tehuantepec is an ideal location to characterize ‘upstream’ atmospheric processes linking the Pacific and Atlantic sectors because a prominent gap in the Sierra Madre mountains forces low-level winds to flow through the Isthmus of Tehuantepec toward the Pacific, driving local upwelling of deeper, lower radiocarbon waters to the surface. A preliminary model results and sediment core measurements leverage this wind-to-radiocarbon relationship to provide a precious constraint on Northern Hemisphere atmospheric dynamics over the past 23,000-years. Previous studies of contemporary climate variability and preliminary examinations of models and observational products indicate that higher atmospheric pressure over North America is associated with high near-surface pressure in the Gulf of Mexico, leading to stronger Tehuantepec winds. The project suggested here—including new sediment proxy measurements, model (Paleoclimate GCM) and data product examinations, and forward modeling—aims to discover the driving mechanisms behind the variability in Tehuantepec gap wind strength over paleoclimate timescales, which will provide a crucial new constraint on glacial-interglacial atmospheric dynamics in addition to controls on tropical Pacific Sea Surface Temperature and inter-basin moisture fluxes.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.