In a warming world, what drives cooling and freshening in the South Pacific Ocean?

整个地球正在变暖。然而，在2006年至2013年期间，在东南太平洋观测到冷却和新鲜。与此同时，南极海冰经向输送的淡水输出呈现出积极的趋势，在南太平洋最为强烈。这个项目将研究最近南太平洋变冷和变冷趋势的机制。特别令人感兴趣的是海冰在淡水产生和海气热通量调制中的作用。拟议的工作将有助于了解南大洋（SO）对气候变化的响应，包括上层海洋热量和淡水含量、海冰覆盖和融水输出的变化。这些结果与生物地球化学等其他学科相关，并将指导我们对碳循环变化的理解。研究结果将发表在科学期刊上，并在重要会议上发表。项目外展部分包括计划通过斯克里普斯海洋学研究所本科生研究奖学金（SURF）本科生研究经验（REU）项目每年向一名本科生提供建议，以及计划为高中科学教师提供为期5天的系列研讨会，帮助他们开发工具和策略，以教授对广泛的非科学界具有重要意义的最新科学成果。总体目标是了解海冰、海洋和大气之间的相互联系，描述控制这些变化的机制，以及它们的年际到年代际变化。近几十年来在南大洋观测到的强烈变化对上层海洋的热量和淡水含量产生了重大扰动，似乎也对碳含量产生了重大影响。海冰覆盖的变化与观测到的南大洋水文变化和海气浮力通量的变化密切相关。将根据南大洋主要水团形成速率的变化来解释控制各个分量的时空变异性的物理过程。这将有助于确定海洋与大气耦合最强烈的位置，从而对大气变化最敏感，提供有关准确描述和解释南大洋水文所需的大气和海冰状态观测要求的宝贵信息。虽然建议的工作将集中在南大洋的水团转变过程，但其结果可能适用于理解全球经向翻转环流，并且这里应用的方法也应该扩展到北半球。该项目将导致评估现有通量测量的准确性，评估水团转变过程对通量定义的敏感性，并将由此产生的要求分发给全球海洋观测系统和全球气候观测系统规划小组。

As a whole the earth is warming. Yet cooling and freshening have been observed in the Southeastern Pacific, in the well-instrumented period of 2006 to 2013. At the same time freshwater export by meridional transport of Antarctic sea-ice has shown a positive trend that is strongest in the South Pacific Ocean. This project will investigate the mechanism of this recent South Pacific cooling and freshening trend. Of particular interest is the role of sea ice in the generation of fresh water and the modulation of air-sea flux heat fluxes. The proposed work will contribute to understanding of the Southern Ocean (SO) response to climate change, including changes in the upper ocean heat and freshwater content, sea-ice cover and melt water export. These results are relevant for other disciplines such as biogeochemistry, and will guide our understanding of carbon cycle changes. The results will be published in scientific journals and presented at major meetings. The project outreach components include plans to advise one undergraduate student per year through the Scripps Institution of Oceanography Undergraduate Research Fellowship (SURF) Research Experiences for Undergraduates (REU) program as well as plans for a 5-day workshop series for high school science teachers to help them develop tools and strategies for teaching the most up-to-date scientific results that are of significant importance for wide, non-scientific community. The overall goal is to understand the interconnections between sea ice, ocean, and atmosphere, to describe the mechanisms that govern these changes, as well as their interannual to interdecadal variability. Strong changes observed in the Southern Ocean in recent decades represent significant perturbations to the upper ocean heat and freshwater content and seem to have significant impact on carbon content, as well. Changes in sea-ice cover are strongly linked to observed changes in the Southern Ocean hydrography and to changes in air-sea buoyancy fluxes. The physical processes governing the temporal and spatial variability of individual components will be interpreted in relation to the variability in formation rates of the major Southern Ocean water masses. This will facilitate identification of locations where the ocean is most strongly coupled to the atmosphere, and thus most sensitive to atmospheric changes, providing valuable information on the observational requirements on the atmospheric and sea-ice state needed to accurately describe and interpret Southern ocean hydrology. While the proposed work will focus on water mass transformation processes in the Southern Ocean, the results are likely to be applicable for understanding global meridional overturning circulation, and the methods applied here should be extendable to the Northern Hemisphere as well. The project will lead to an assessment of the accuracy of existing flux measurements, an evaluation of the sensitivity of water mass transformation processes to flux definitions and a dissemination of the resulting requirements to the Global Ocean Observing System and the Global Climate Observing system planning groups.