Collaborative Research: Physical and biological controls on ocean carbon and oxygen uptake in the western North Pacific

了解海洋何时以及如何从大气中吸收碳的机制，对于我们了解海洋地球化学的基础知识和模拟未来气候的能力非常重要。海气之间的氧通量也与气候变化有关，地表氧可作为生物碳生产和输出以及重要物理过程的示踪剂。西北太平洋的黑潮延伸区是一个二氧化碳吸收强烈的区域，也是冬季水团形成的场所，在黑潮延伸区以南形成了副热带模态水，在黑潮延伸区以北形成了较轻和较密集的中央模态水。这些模式沃茨然后下沉到海面以下，将二氧化碳移动到海洋内部。有很少的冬季垂直剖面的任何碳系统参数在这些模式水的形成区域，并没有完全解决冬季或年度周期的测量。在这个项目中，研究人员将部署机器人剖面浮标来进行这些所需的测量。他们将联合收割机的浮动数据与数值模拟相结合，以促进模式水的形成和大气-海洋的二氧化碳和氧气通量在这一重要地区的理解。该提案将资助一名早期职业科学家，并扩大夏威夷大学地球化学分析浮子操作的专业知识和能力，为自主地球化学平台的未来工作奠定基础。这项提案将资助一名研究生攻读博士学位。工作和多个夏季本科研究人员。学生将接触到海洋化学，海洋物理学和气候模型的互补领域。该小组将从以下方面调查西北太平洋的碳和氧预算：氧，硝酸盐和估计的溶解无机碳的新浮子观测;用于水团分析的长期浮子温度和盐度观测;以及模型输出。他们将部署能够测量黑潮延伸区亚热带和中央模式水形成区域中心pH值的地球化学Argo浮标，以提供氧气，硝酸盐的垂直分布，特别是溶解无机碳的估计。他们将利用这些观测结果来计算气-海二氧化碳和氧气通量的驱动因素，并验证模型输出以供进一步分析。西部边界流，如黑潮延伸区，是重要的二氧化碳吸收区，但生物学和物理学对这种吸收的相对重要性及其在大的时空尺度上的变化还没有得到很好的理解。该项目有三个主要目标：（1）确定在北太平洋的CO2和O2吸收中有多少是模态水形成和俯冲的结果;（2）确定在黑潮延伸区驱动海气通量的物理和生物过程在空间上是如何变化的;以及（3）分析黑潮延伸区模态水形成和相关气体通量的年际和年代际变化的驱动因素，并确定这种变化如何与较大的气候系统新的观测结果将在几十年的船舶观测和近二十年的剖面浮标物理观测的大背景下进行评估。该小组将利用模型输出来诊断海气通量的物理驱动因素，并将观测到的机制与长期变率和气候过程联系起来。所收集的数据将代表第一个季节性解决的配置文件中的氧气，硝酸盐，并派生DIC在西部边界电流，并将使用到一个广泛的社区researchers.This奖项反映了NSF的法定使命，并已被认为是值得通过评估使用基金会的智力价值和更广泛的影响审查标准的支持。

Understanding the mechanisms that determine when and how the ocean takes up carbon from the atmosphere is important to our fundamental knowledge of ocean biogeochemistry and to our ability to model future climate. Air-sea fluxes of oxygen are also relevant to climatic variability, and surface oxygen can act as a tracer of biological carbon production and export as well as of important physical processes. The Kuroshio Extension region of the northwest Pacific Ocean is an area of strong carbon dioxide uptake and a site of wintertime watermass formation, with Subtropical Mode Water formed to the south of the Kuroshio Extension and lighter and denser Central Mode Water formed to the north. These mode waters then sink below the surface, moving carbon dioxide to the ocean interior. There are very few wintertime vertical profiles of any carbon system parameter in these mode water formation regions and no fully resolved winter or annual cycles of measurements. In this project, the investigators will deploy robotic profiling floats to make these needed measurements. They will combine the float data with numerical modeling to advance understanding of mode water formation and air-sea fluxes of carbon dioxide and oxygen in this important region. This proposal will fund an early career scientist and expand expertise in and capability for biogeochemical profiling float operations at the University of Hawai’i, providing a foundation for future work in autonomous biogeochemical platforms. This proposal will fund a graduate student in their Ph.D. work and multiple summer undergraduate researchers. Students will gain exposure to the complementary fields of marine chemistry, ocean physics, and climate models. The team will investigate carbon and oxygen budgets in the northwest Pacific from the following: new float observations of oxygen, nitrate, and estimated dissolved inorganic carbon; longer-term float temperature and salinity observations for water mass analysis; and model output. They will deploy biogeochemical Argo floats capable of measuring pH in the heart of the Subtropical and Central Mode Water formation regions in the Kuroshio Extension to provide vertical profiles of oxygen, nitrate, and, especially, estimates of dissolved inorganic carbon. They will use these observations to both calculate the drivers of air-sea carbon dioxide and oxygen fluxes and to validate model output for further analysis. Western boundary currents, such as the Kuroshio Extension, are areas of significant carbon dioxide uptake, but the relative importance of biology and physics to that uptake and its variability on large temporal and spatial scales is not well understood. The project has three main goals: (1) to determine what fraction of the CO2 and O2 uptake in the North Pacific is the result of mode water formation and subduction, (2) to determine how the physical and biological processes that drive air-sea fluxes vary spatially in the Kuroshio Extension region, and (3) to analyze the drivers of interannual and decadal variability of mode water formation and related gas fluxes in the Kuroshio Extension region and determine how that variability is linked to the larger climate system. The new observations will be evaluated in the larger context of multiple decades of observations from ships and almost two decades of physical observations from profiling floats. The team will use model output to diagnose physical drivers of air-sea fluxes and to link the observed mechanisms to longer-term variability and climate processes. The data collected will represent the first seasonally resolved profiles of oxygen, nitrate, and derived DIC in a western boundary current and will be of use to a broad community of researchers.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.