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地方海拔较低，足以让风从大西洋吹到太平洋。这些风隙的最北端是“特万特佩克峡”（沿墨西哥西南海岸）。这些当地已知的风（这里简称为特万特佩克峡风）主要在冬季，当北美的高大气压在特万特佩克地峡上形成压力梯度时，将凉爽、富含营养的水强烈地上涌到墨西哥湾。尽管特万特佩克峡风作为大西洋-太平洋遥连的潜在重要性，但在快速和全球气候变化的背景下，还没有尝试预测这些风对区域气候动力学变化的响应。研究人员建议将过去上升流的气候记录（来自过去3万年的沉积放射性碳）和模式模拟结合起来，以表征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-大气反馈机制，其中特万特佩克间隙风和大气罗斯比波发挥了核心作用。该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（西班牙裔服务机构和美洲土著太平洋岛民服务机构）本科生的教育和科学培训。研究人员将继续参与他们机构的扩大参与努力，包括大气，海洋和冰冻圈科学的ATOC REU (NSF 2150262)，这是一个主要从西班牙裔服务机构招募的项目，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，将制定一项以地球气候的长期变化为重点的课程计划，并通过加州外展项目的环境气候变化和扫盲项目进行试点，并发布在一个公开可用的国家气候教学法在线存储库中（称为“受制于气候”）。特万特佩克湾是表征连接太平洋和大西洋部分的“上游”大气过程的理想地点，因为马德雷山脉的一个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、低放射性碳水的上升流到地表。初步的模型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23000年北半球大气动力学提供了宝贵的约束。先前对当代气候变率的研究以及对模式和观测产品的初步检验表明，北美地区较高的大气压力与墨西哥湾近地表高压有关，从而导致更强的特万特佩克风。本文提出的项目包括新的沉积物代用测量、古气候GCM模型和数据产品检验以及正模拟，旨在发现特万特佩克间隙风强度在古气候时间尺度上变化的驱动机制，除了控制热带太平洋海面温度和盆地间水分通量外，还将为冰川-间冰期大气动力学提供重要的新约束。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。

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.