Collaborative Research: Downstream Impacts of the South Pacific Tropical Water

对南太平洋热带水（SPTW）的观测揭示了年际时间尺度的变化以及几十年来盐度增加的趋势。 SPTW 是由浅层盐度最大形成的，在南太平洋东部形成，并在副热带环流中和沿赤道输送。 SPTW 的变化可能会影响赤道地区的环流和水特性，特别是在盐度和温度异常未得到密度补偿的情况下。 SPTW具有显着的内赤道路径，因此停留时间相对较短（5-15年），形成率较高。 因此，预计 SPTW 对赤道太平洋的贡献将比北太平洋的贡献更快、更强。 该项目将更全面地了解赤道海洋如何通过南太平洋水域的俯冲进行通风，以及这种通风的变化如何影响气候变化。 该项目的总体研究目标是：识别 SPTW 的变异性，并评估这种变异性的下游影响。 将研究 SPTW 变化与年际和长期大气强迫的关系。 根据 SPTW 变化的程度和幅度，假设热带南太平洋的下游环流和热结构将存在动力特征。 该研究包括对现有 Argo 浮动剖面和 WOCE/CLIVAR 示踪剂（盐度、位涡、氧气、CFC、SF6、氚、氦 3、14C 等）数据的分析，以及地球模拟器 (OFES) OGCM 的结果，以及来自估计海洋环流和气候 (ECCO) 的模拟被动和伴随示踪剂。智力价值：该项目将利用所有可用的水文学（主要是 Argo）和示踪观测来识别 SPTW 的变化。 观测结果与高分辨率 GCM 的结果相结合，将能够对这种变化及其对热带太平洋环流和热结构的下游影响进行全面、物理一致的解释。 此外，模拟被动示踪剂及其伴随物将提供明确的方法来识别 SPTW 路径，特别是评估中尺度涡流和小尺度过程的影响。 SPTW 对赤道东太平洋的赤道潜流和上涌水产生影响，两者都与 ENSO 直接相关。 对 SPTW 下游影响的衍生评估将增强对海洋在气候变率中的作用的理解，并为年际和较长时间尺度变率（如太平洋 ENSO 和 PDO）的可预测性和预测提供新信息。 更广泛的影响：该项目将提高使用 ENSO 和气候预测的技能；通过对博士后和研究生进行观测数据和模型输出分析方面的培训，推动科学发展，同时促进教育；通过建立不同学科和不同机构之间的合作，加强研究和教育基础设施；利用高分辨率 GCM 的现有观测结果和结果来评估气候变化，造福社会。 其中一名 PI 参与了“指导物理海洋学女性以提高保留率”计划，并且是向迈阿密大学提供的 NSF 预付款实施委员会的成员。

Observations of South Pacific Tropical Water (SPTW) have revealed variability on interannual time scales and a trend of increasing salinity over several decades. SPTW identified by a shallow salinity maximum forms in the eastern South Pacific and is transported in the subtropical gyre and along the equator. Variability of SPTW may affect the circulation and water properties in the equatorial region, in particular if the salinity and temperature anomalies are not density compensated. SPTW has a significant interior equatorward pathway, and thus a relatively short (5-15 years) residence time and high formation rate. As a consequence, the contribution of SPTW to the equatorial Pacific is expected to be faster and stronger than its North Pacific counterpart. This project will initiate a more complete understanding of how the equatorial ocean is ventilated through the subduction of South Pacific waters and how variability in this ventilation contributes to climate variability. The overall research objectives of the project are: to identify variability in SPTW, and to assess downstream impacts of this variability. The relationship of SPTW variability to interannual and longer term atmospheric forcing will be investigated. Depending on the extent and magnitude of the SPTW variability, it is hypothesized that there will be a dynamical signature in the downstream circulation and thermal structure of the tropical South Pacific. The research includes the analysis of available Argo floating profiles and WOCE/CLIVAR tracer (salinity, potential vorticity, oxygen, CFC, SF6, tritium, helium-3, 14C, etc.) data, as well as results from the OGCM for the Earth Simulator (OFES), and simulated passive and adjoint tracers from the Estimating the Circulation and Climate of the Ocean (ECCO).Intellectual merit: The project will utilize all available hydrographic (mainly Argo) and tracer observations to identify the variability of SPTW. The combined use of observations with results from high-resolution GCMs will allow for a comprehensive, physically consistent interpretation of this variability and its downstream impacts on the tropical Pacific Ocean circulation and thermal structure. In addition, the simulated passive tracer and its adjoint will provide unambiguous means to identify the SPTW pathways and in particular to assess the influence of meso-scale eddies and small scale processes. The SPTW contributes to the Equatorial Undercurrent and water upwelled in the eastern equatorial Pacific, both having direct relevance to ENSO. The derived assessment of the SPTW downstream impacts will enhance the understanding of ocean?s role in climate variability, and provide new information for the predictability and prediction of interannual and longer time scale variability such as ENSO and PDO in the Pacific. Broader impacts: The project will lead to improved skills for use with ENSO and climate prediction; advance science while promoting education by the training of a postdoctoral fellow and a graduate student in the analysis of observational data and model outputs; enhance infrastructure for research and education by establishing collaborations between different disciplines and different institutions; and benefit the society by the use of existing observations and results from high-resolution GCMs to assess climate change. One of the PIs participates in the program Mentoring Physical Oceanography Women to Increase Retention, and is on the implementation committee of an NSF Advance grant to the University of Miami.