The Annual Cycle of the Biological Carbon Pump in the Subpolar North Atlantic

海洋生物在地球的碳循环中起着重要作用。在阳光照射下的海洋表层水中，浮游植物产生的大部分有机物质在表层水中被吃掉并被循环利用，还有一小部分以所谓的“生物碳泵”的形式沉入深海。生物泵在高纬度地区尤其难以研究，因为高纬度地区很难到达，工作起来也很有挑战性。了解海洋这些部分的生物泵也尤为重要，世界上大部分深海水域都是在这些部分形成的。通过仔细测量留在地表水中的过量氧气的数量，可以估计向深水输出的碳。使用部署在系泊、浮子和滑翔机上的传感器，可以非常精确地测量海水中的氧气。这些传感器可以一次部署数年，但它们的测量必须仔细校准。在这个项目中，研究人员将使用经过仔细校准的滑翔机氧气传感器，依次校准北大西洋高纬度系泊处的氧气传感器，在两年的时间里研究生物碳泵。该项目将培训几名本科生和一名研究生，并开发出包含该项目中滑翔机和系泊数据的教育实验室材料。本提案的目标是通过使用海洋观测站倡议（OOI） Irminger海洋阵列的生物地球化学传感器测量，在观测上限制生物碳泵的年量级和季节时序（确定为年度净群落产量；ANCP）及其对海气二氧化碳通量的影响。然而，现有的OOI氧传感器校准受到部署前和部署后漂移的影响，目前无法通过氧质量平衡计算ANCP。因此，研究人员建议通过部署两个滑翔机来配置氧气传感器的空气校准，以提高OOI Irminger Sea氧气测量的准确性和实用性。这些空气校准滑翔机将用于对Irminger海上阵列上现有的所有12个氧气传感器进行相互校准，并结合所有传感器的数据产生校准的氧气产品，这将确保计算ANCP的足够精度。包括上层海洋生物生产力和温跃层呼吸在内的ANCP的年幅度和季节时间，将在数据受限的一维物理模型中使用氧质量平衡方法确定。将使用一套一维模型模拟，包括无机碳系统、气体交换和由氧质量平衡确定的ANCP，以及OOI二氧化碳测量，以诊断空气-海洋二氧化碳通量的物理和生物驱动因素的影响，提高对生物泵如何影响碳循环的定量和机制理解。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。

Ocean biology plays an important role in the Earth's carbon cycle. While most of the organic material produced by phytoplankton in the sunlit surface waters of the oceans is eaten and recycled in the surface waters, a small amount sinks to the deep ocean in what is called the "biological carbon pump." The biological pump is particularly hard to study in high latitude regions, which can be difficult to get to and challenging to work in. It is also particularly important to understand the biological pump in these parts of the ocean, where much of the world's deep ocean waters are formed. The export of carbon to deep waters can be estimated by carefully measuring the amount of excess oxygen left behind in surface waters. Oxygen in seawater can be measured very precisely using sensors deployed on moorings, floats, and gliders. These sensors can be deployed for years at a time, but their measurements must be carefully calibrated. In this project, investigators would use carefully calibrated oxygen sensors on gliders to, in turn, calibrate the oxygen sensors on a set of moorings in the high latitude North Atlantic Ocean, to study the biological carbon pump over a period of two years. The project would train several undergraduate students and a graduate student, and result in the development of educational laboratory materials that incorporate glider and mooring data from the project.The goal of this proposal is to observationally constrain the annual magnitude and seasonal timing of the biological carbon pump (determined as annual net community production; ANCP) and its influence on air-sea carbon dioxide flux by using biogeochemical sensor measurements from the Ocean Observatories Initiative (OOI) Irminger Sea Array. However, existing OOI oxygen sensor calibration suffers from both pre- and post-deployment drift, currently precluding the ability to calculate ANCP by oxygen mass balance. The investigators therefore propose to improve the accuracy and utility of OOI Irminger Sea oxygen measurements by deploying two gliders configured for air calibration of their oxygen sensors when surfacing between profiles. These air-calibrated gliders will be used to intercalibrate all 12 existing oxygen sensors on the Irminger Sea Array and produce a calibrated oxygen product incorporating data from all sensors, which will ensure sufficient accuracy to calculate ANCP. Both the annual magnitude and seasonal timing of ANCP, including upper ocean biological productivity and thermocline respiration, will be determined using an oxygen mass balance approach within a data- constrained 1D physical model. A suite of 1D model simulations including the inorganic carbon system, gas exchange, and ANCP determined from oxygen mass balance will be used, together with OOI carbon dioxide measurements, to diagnose influences of physical and biological drivers of air-sea carbon dioxide flux, improving both quantitative and mechanistic understanding of how the biological pump influences the carbon cycle.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.