Collaborative Research: Autonomous Measurements of Carbon Fluxes in the North Atlantic Bloom

大西洋50度以北海域的二氧化碳净吸纳量约占全球总量的25%。生物泵，最重要的是每年春天发生的浮游植物水华，推动了这种吸收。以前的研究表明了水华发生期间小的时间和空间尺度，即生态系统斑块的重要性，但由于船舶研究的内在限制，在解决这些尺度上的成功有限。自主平台和传感器的最新进展现在使持续测量关键数量和速率成为可能产生广泛影响的新方法。在这项研究中，华盛顿大学和缅因州大学奥罗诺分校的PI提出了一个过程实验，重点放在海洋碳系统的一个重要组成部分--北大西洋春季水华--既是因为它的内在优点，也是为了开发成功使用这些新方法推动下一代海洋观测所需的战略和知识的试验台。PI将使用拉格朗日浮标来跟踪混合层中的水块，每个浮标与巡回滑翔机相结合，以表征其周围环境。漂浮器和滑翔机将在一段时间内以三维方式测量垂直和水平混合速率，以及关键的碳系统组件和速率。浮游植物和有机碳将通过一套光学替代物进行量化，氧气通过两个不同的传感器进行量化，硝酸盐通过紫外光谱进行量化。将使用传感器冗余、250-1000米的参考测量、平台之间的交叉检查以及三个航次的水样分析来维护和验证自主传感器的校准。通过Iridium卫星的双向通信将使采样战略能够根据观察到的条件而演变。测量将在60度左右进行，从2008年3月底，也就是花季之前，到7月初花季结束时。初级生产力和碳通量将根据经水平和垂直混合影响校正后的氧、硝酸盐和生物质替代品库存的变化来计算。这些数据与由伴随分析指导的生物物理生态系统模型的系统比较将被用来评估这种模型在通过水华的演变预测小尺度斑块和净碳吸收方面的适当性。最重要的更广泛的影响将是对上述海洋碳系统测量技术的影响。拟议的工作还将支持对4名海洋观测研究生以及本科生实习生进行多学科培训。私营部门将与COSEE-海洋系统合作，编写一篇关于北大西洋生态系统作用的“故事”，引起非科学家的共鸣，并纳入国家科学教育内容标准中确定的领域。最后，该项目将与达尔豪西大学的一位加拿大科学家建立国际合作。

Net uptake of carbon dioxide in the Atlantic Ocean north of 50 degN accounts for about 25% of the global total. The biological pump, most importantly the phytoplankton bloom occurring each spring, drives this uptake. Previous studies have shown the importance of small temporal and spatial scales, i.e. ecosystem patchiness, during the bloom, but have had limited success in resolving these scales due to the inherent limitations of ship-based research. Recent advances in autonomous platforms and sensors now enable new approaches to sustained measurement of key quantities and rates that have potentially broad impacts. In this research, PIs from the University of Washington and the University of Maine-Orono, propose a process experiment focusing on an important component of the oceanic carbon system - the North Atlantic Spring Bloom - both for its intrinsic merit and as a test-bed for developing the strategies and knowledge needed to successfully use these new methods to drive the next generation of ocean observations. The PIs will use Lagrangian floats to follow water parcels in the mixed layer, with each float coupled with roving gliders to characterize its surroundings. The floats and gliders will measure - in three dimensions over time - the vertical and horizontal mixing rates, and key carbon system components and rates. Phytoplankton and organic carbon will be quantified through a suite of optical proxies, oxygen by two different sensors, and nitrate by UV spectrometry. Redundancy of sensors, reference measurements at 250-1000m, cross-checking among platforms and water sample analysis on three cruises will be used to maintain and verify the calibration of the autonomous sensors. Two-way communication via Iridium satellite will allow sampling strategies to evolve in response to observed conditions. Measurements will be made near 60 degN from late March 2008, before the bloom, through early July when it has ended. Primary productivity and carbon fluxes will be calculated from changes in inventories of oxygen, nitrate and biomass proxies corrected for the effects of horizontal and vertical mixing. Systematic comparison of these data with a bio-physical ecosystem model guided by adjoint analysis will be used to evaluate the appropriateness of such models for predicting both small-scale patchiness and net carbon uptake through the evolution of the bloom. The most important broader impact will be on the technology of ocean carbon system measurement as described above. The proposed work will also support multidisciplinary training of four graduate students in ocean observing, as well as undergraduate interns. The PIs will collaborate with the COSEE-Ocean Systems to develop a "story" on the role of the North Atlantic ocean ecosystem that will resonate with non-scientists and be integrated into areas identified in the National Science Education Content Standards. Finally, the project will build international collaboration with a Canadian scientist at Dalhousie University.